fix output

The invariant check system had grown into a single monolithic file pair containing 24 invariant checker classes. The large `InvariantCheck.cpp` file was a frequent source of merge conflicts and difficult to navigate. This refactoring improves maintainability and readability with zero behavioral changes.

In particular, this change:
- Splits `InvariantCheck.h` and `InvariantCheck.cpp` into 10 focused header/source pairs organized by domain under a new `invariants/` subdirectory.
- Extracts the shared `Privilege` enum and `hasPrivilege()` function into a dedicated `InvariantCheckPrivilege.h` header, so domain-specific files can reference them independently.

.github/scripts/strategy-matrix/generate.py

@@ -32,10 +32,13 @@ We will further set additional CMake arguments as follows:
 """
 
 
-def generate_strategy_matrix(all: bool, config: Config) -> list:
+def generate_strategy_matrix(all: bool, config: Config, distro: str = "") -> list:
     configurations = []
+    os_entries = config.os
+    if distro:
+        os_entries = [o for o in os_entries if o["distro_name"] == distro]
     for architecture, os, build_type, cmake_args in itertools.product(
-        config.architecture, config.os, config.build_type, config.cmake_args
+        config.architecture, os_entries, config.build_type, config.cmake_args
     ):
         # The default CMake target is 'all' for Linux and MacOS and 'install'
         # for Windows, but it can get overridden for certain configurations.
@@ -223,7 +226,7 @@ def generate_strategy_matrix(all: bool, config: Config) -> list:
         if (n := os["compiler_version"]) != "":
             config_name += f"-{n}"
         config_name += (
-            f"-{architecture['platform'][architecture['platform'].find('/')+1:]}"
+            f"-{architecture['platform'][architecture['platform'].find('/') + 1 :]}"
         )
         config_name += f"-{build_type.lower()}"
         if "-Dcoverage=ON" in cmake_args:
@@ -313,21 +316,32 @@ if __name__ == "__main__":
         required=False,
         type=Path,
     )
+    parser.add_argument(
+        "-d",
+        "--distro",
+        help="Filter OS entries to only include those with this distro_name (e.g. 'debian', 'rhel', 'ubuntu').",
+        required=False,
+        type=str,
+        default="",
+    )
     args = parser.parse_args()
 
     matrix = []
     if args.config is None or args.config == "":
         matrix += generate_strategy_matrix(
-            args.all, read_config(THIS_DIR / "linux.json")
+            args.all, read_config(THIS_DIR / "linux.json"), args.distro
         )
         matrix += generate_strategy_matrix(
-            args.all, read_config(THIS_DIR / "macos.json")
+            args.all, read_config(THIS_DIR / "macos.json"), args.distro
         )
         matrix += generate_strategy_matrix(
-            args.all, read_config(THIS_DIR / "windows.json")
+            args.all, read_config(THIS_DIR / "windows.json"), args.distro
         )
     else:
-        matrix += generate_strategy_matrix(args.all, read_config(args.config))
+        matrix += generate_strategy_matrix(
+            args.all, read_config(args.config), args.distro
+        )
 
     # Generate the strategy matrix.
     print(f"matrix={json.dumps({'include': matrix})}")
+    # print(json.dumps(matrix, indent=2))

.github/workflows/on-pr.yml

@@ -128,12 +128,23 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [linux, macos, windows]
+        include:
+          - os: linux
+            distro: debian
+          - os: linux
+            distro: rhel
+          - os: linux
+            distro: ubuntu
+          - os: macos
+            distro: ""
+          - os: windows
+            distro: ""
     with:
       # Enable ccache only for events targeting the XRPLF repository, since
       # other accounts will not have access to our remote cache storage.
       ccache_enabled: ${{ github.repository_owner == 'XRPLF' }}
       os: ${{ matrix.os }}
+      distro: ${{ matrix.distro }}
     secrets:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 

.github/workflows/on-trigger.yml

@@ -77,7 +77,17 @@ jobs:
     strategy:
       fail-fast: ${{ github.event_name == 'merge_group' }}
       matrix:
-        os: [linux, macos, windows]
+        include:
+          - os: linux
+            distro: debian
+          - os: linux
+            distro: rhel
+          - os: linux
+            distro: ubuntu
+          - os: macos
+            distro: ""
+          - os: windows
+            distro: ""
     with:
       # Enable ccache only for events targeting the XRPLF repository, since
       # other accounts will not have access to our remote cache storage.
@@ -86,6 +96,7 @@ jobs:
       # not identical to a regular compilation.
       ccache_enabled: ${{ github.repository_owner == 'XRPLF' && !startsWith(github.ref, 'refs/heads/release') }}
       os: ${{ matrix.os }}
+      distro: ${{ matrix.distro }}
       strategy_matrix: ${{ github.event_name == 'schedule' && 'all' || 'minimal' }}
     secrets:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

.github/workflows/pre-commit.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   # Call the workflow in the XRPLF/actions repo that runs the pre-commit hooks.
   run-hooks:
-    uses: XRPLF/actions/.github/workflows/pre-commit.yml@320be44621ca2a080f05aeb15817c44b84518108
+    uses: XRPLF/actions/.github/workflows/pre-commit.yml@56de1bdf19639e009639a50b8d17c28ca954f267
     with:
       runs_on: ubuntu-latest
       container: '{ "image": "ghcr.io/xrplf/ci/tools-rippled-pre-commit:sha-41ec7c1" }'

.github/workflows/reusable-build-test.yml

@@ -26,6 +26,12 @@ on:
         type: string
         default: "minimal"
 
+      distro:
+        description: 'Filter to only include configs for this distro (e.g. "debian", "rhel", "ubuntu"). Leave empty for no filtering.'
+        required: false
+        type: string
+        default: ""
+
     secrets:
       CODECOV_TOKEN:
         description: "The Codecov token to use for uploading coverage reports."
@@ -38,9 +44,11 @@ jobs:
     with:
       os: ${{ inputs.os }}
       strategy_matrix: ${{ inputs.strategy_matrix }}
+      distro: ${{ inputs.distro }}
 
   # Build and test the binary for each configuration.
   build-test-config:
+    name: ${{ matrix.config_name }}
     needs:
       - generate-matrix
     uses: ./.github/workflows/reusable-build-test-config.yml

.github/workflows/reusable-strategy-matrix.yml

@@ -13,6 +13,11 @@ on:
         required: false
         type: string
         default: "minimal"
+      distro:
+        description: 'Filter to only include configs for this distro (e.g. "debian", "rhel", "ubuntu"). Leave empty for no filtering.'
+        required: false
+        type: string
+        default: ""
     outputs:
       matrix:
         description: "The generated strategy matrix."
@@ -42,4 +47,5 @@ jobs:
         env:
           GENERATE_CONFIG: ${{ inputs.os != '' && format('--config={0}.json', inputs.os) || '' }}
           GENERATE_OPTION: ${{ inputs.strategy_matrix == 'all' && '--all' || '' }}
-        run: ./generate.py ${GENERATE_OPTION} ${GENERATE_CONFIG} >> "${GITHUB_OUTPUT}"
+          GENERATE_DISTRO: ${{ inputs.distro != '' && format('--distro={0}', inputs.distro) || '' }}
+        run: ./generate.py ${GENERATE_OPTION} ${GENERATE_CONFIG} ${GENERATE_DISTRO} >> "${GITHUB_OUTPUT}"

.pre-commit-config.yaml

@@ -61,7 +61,15 @@ repos:
     hooks:
       - id: nix-fmt
         name: Format Nix files
-        entry: nix --extra-experimental-features 'nix-command flakes' fmt
+        entry: |
+          bash -c '
+            if command -v nix &> /dev/null || [ "$GITHUB_ACTIONS" = "true" ]; then
+              nix --extra-experimental-features "nix-command flakes" fmt "$@"
+            else
+              echo "Skipping nix-fmt: nix not installed and not in GitHub Actions"
+              exit 0
+            fi
+          ' --
         language: system
         types:
           - nix

cmake/XrplConfig.cmake

@@ -16,6 +16,8 @@ find_dependency(Boost
                 COMPONENTS
                 chrono
                 container
+                context
+                coroutine
                 date_time
                 filesystem
                 program_options

cmake/XrplInterface.cmake

@@ -22,6 +22,7 @@ target_compile_definitions(
               BOOST_FILESYSTEM_NO_DEPRECATED
               >
               $<$<NOT:$<BOOL:${boost_show_deprecated}>>:
+              BOOST_COROUTINES_NO_DEPRECATION_WARNING
               BOOST_BEAST_ALLOW_DEPRECATED
               BOOST_FILESYSTEM_DEPRECATED
               >

cmake/deps/Boost.cmake

@@ -4,6 +4,7 @@ include(XrplSanitizers)
 find_package(Boost REQUIRED
              COMPONENTS chrono
                         container
+                        coroutine
                         date_time
                         filesystem
                         json
@@ -20,6 +21,7 @@ target_link_libraries(
     INTERFACE Boost::headers
               Boost::chrono
               Boost::container
+              Boost::coroutine
               Boost::date_time
               Boost::filesystem
               Boost::json

conanfile.py

@@ -196,6 +196,7 @@ class Xrpl(ConanFile):
             "boost::headers",
             "boost::chrono",
             "boost::container",
+            "boost::coroutine",
             "boost::date_time",
             "boost::filesystem",
             "boost::json",

cspell.config.yaml

@@ -71,14 +71,12 @@ words:
   - coldwallet
   - compr
   - conanfile
-  - cppcoro
   - conanrun
   - confs
   - connectability
   - coro
   - coros
   - cowid
-  - cppcoro
   - cryptocondition
   - cryptoconditional
   - cryptoconditions
@@ -101,14 +99,11 @@ words:
   - endmacro
   - exceptioned
   - Falco
-  - fcontext
   - finalizers
   - firewalled
-  - fcontext
   - fmtdur
   - fsanitize
   - funclets
-  - gantt
   - gcov
   - gcovr
   - ghead
@@ -190,7 +185,6 @@ words:
   - ostr
   - pargs
   - partitioner
-  - pratik
   - paychan
   - paychans
   - permdex
@@ -198,7 +192,6 @@ words:
   - permissioned
   - pointee
   - populator
-  - pratik
   - preauth
   - preauthorization
   - preauthorize
@@ -213,7 +206,6 @@ words:
   - queuable
   - Raphson
   - replayer
-  - repost
   - rerere
   - retriable
   - RIPD
@@ -244,7 +236,6 @@ words:
   - soci
   - socidb
   - sslws
-  - stackful
   - statsd
   - STATSDCOLLECTOR
   - stissue

include/xrpl/core/Coro.ipp

@@ -0,0 +1,122 @@
+#pragma once
+
+#include <xrpl/basics/ByteUtilities.h>
+
+namespace xrpl {
+
+template <class F>
+JobQueue::Coro::Coro(Coro_create_t, JobQueue& jq, JobType type, std::string const& name, F&& f)
+    : jq_(jq)
+    , type_(type)
+    , name_(name)
+    , running_(false)
+    , coro_(
+          [this, fn = std::forward<F>(f)](
+              boost::coroutines::asymmetric_coroutine<void>::push_type& do_yield) {
+              yield_ = &do_yield;
+              yield();
+              fn(shared_from_this());
+#ifndef NDEBUG
+              finished_ = true;
+#endif
+          },
+          boost::coroutines::attributes(megabytes(1)))
+{
+}
+
+inline JobQueue::Coro::~Coro()
+{
+#ifndef NDEBUG
+    XRPL_ASSERT(finished_, "xrpl::JobQueue::Coro::~Coro : is finished");
+#endif
+}
+
+inline void
+JobQueue::Coro::yield() const
+{
+    {
+        std::lock_guard lock(jq_.m_mutex);
+        ++jq_.nSuspend_;
+    }
+    (*yield_)();
+}
+
+inline bool
+JobQueue::Coro::post()
+{
+    {
+        std::lock_guard lk(mutex_run_);
+        running_ = true;
+    }
+
+    // sp keeps 'this' alive
+    if (jq_.addJob(type_, name_, [this, sp = shared_from_this()]() { resume(); }))
+    {
+        return true;
+    }
+
+    // The coroutine will not run.  Clean up running_.
+    std::lock_guard lk(mutex_run_);
+    running_ = false;
+    cv_.notify_all();
+    return false;
+}
+
+inline void
+JobQueue::Coro::resume()
+{
+    {
+        std::lock_guard lk(mutex_run_);
+        running_ = true;
+    }
+    {
+        std::lock_guard lock(jq_.m_mutex);
+        --jq_.nSuspend_;
+    }
+    auto saved = detail::getLocalValues().release();
+    detail::getLocalValues().reset(&lvs_);
+    std::lock_guard lock(mutex_);
+    XRPL_ASSERT(static_cast<bool>(coro_), "xrpl::JobQueue::Coro::resume : is runnable");
+    coro_();
+    detail::getLocalValues().release();
+    detail::getLocalValues().reset(saved);
+    std::lock_guard lk(mutex_run_);
+    running_ = false;
+    cv_.notify_all();
+}
+
+inline bool
+JobQueue::Coro::runnable() const
+{
+    return static_cast<bool>(coro_);
+}
+
+inline void
+JobQueue::Coro::expectEarlyExit()
+{
+#ifndef NDEBUG
+    if (!finished_)
+#endif
+    {
+        // expectEarlyExit() must only ever be called from outside the
+        // Coro's stack.  It you're inside the stack you can simply return
+        // and be done.
+        //
+        // That said, since we're outside the Coro's stack, we need to
+        // decrement the nSuspend that the Coro's call to yield caused.
+        std::lock_guard lock(jq_.m_mutex);
+        --jq_.nSuspend_;
+#ifndef NDEBUG
+        finished_ = true;
+#endif
+    }
+}
+
+inline void
+JobQueue::Coro::join()
+{
+    std::unique_lock<std::mutex> lk(mutex_run_);
+    cv_.wait(lk, [this]() { return running_ == false; });
+}
+
+}  // namespace xrpl

include/xrpl/core/CoroTask.h

@@ -1,687 +0,0 @@
-#pragma once
-
-#include <coroutine>
-#include <exception>
-#include <utility>
-#include <variant>
-
-namespace xrpl {
-
-template <typename T = void>
-class CoroTask;
-
-/**
- * CoroTask<void> -- coroutine return type for void-returning coroutines.
- *
- * Class / Dependency Diagram
- * ==========================
- *
- *   CoroTask<void>
- *   +-----------------------------------------------+
- *   | - handle_ : Handle (coroutine_handle<promise>) |
- *   +-----------------------------------------------+
- *   | + handle(), done()                             |
- *   | + await_ready/suspend/resume  (Awaiter iface)  |
- *   +-----------------------------------------------+
- *            |  owns
- *            v
- *   promise_type
- *   +-----------------------------------------------+
- *   | - exception_    : std::exception_ptr           |
- *   | - continuation_ : std::coroutine_handle<>      |
- *   +-----------------------------------------------+
- *   | + get_return_object() -> CoroTask              |
- *   | + initial_suspend()   -> suspend_always (lazy) |
- *   | + final_suspend()     -> FinalAwaiter          |
- *   | + return_void()                                |
- *   | + unhandled_exception()                        |
- *   +-----------------------------------------------+
- *            |  returns at final_suspend
- *            v
- *   FinalAwaiter
- *   +-----------------------------------------------+
- *   | await_suspend(h):                              |
- *   |   if continuation_ set -> symmetric transfer   |
- *   |   else                 -> noop_coroutine        |
- *   +-----------------------------------------------+
- *
- * Design Notes
- * ------------
- * - Lazy start: initial_suspend returns suspend_always, so the coroutine
- *   body does not execute until the handle is explicitly resumed.
- * - Symmetric transfer: await_suspend returns a coroutine_handle instead
- *   of void/bool, allowing the scheduler to jump directly to the next
- *   coroutine without growing the call stack.
- * - Continuation chaining: when one CoroTask is co_await-ed inside
- *   another, the caller's handle is stored as continuation_ so
- *   FinalAwaiter can resume it when this task finishes.
- * - Move-only: the handle is exclusively owned; copy is deleted.
- *
- * Usage Examples
- * ==============
- *
- * 1. Basic void coroutine (the most common case in rippled):
- *
- *      CoroTask<void> doWork(std::shared_ptr<CoroTaskRunner> runner) {
- *          // do something
- *          co_await runner->suspend();   // yield control
- *          // resumed later via runner->post() or runner->resume()
- *          co_return;
- *      }
- *
- * 2. co_await-ing one CoroTask<void> from another (chaining):
- *
- *      CoroTask<void> inner() {
- *          // ...
- *          co_return;
- *      }
- *      CoroTask<void> outer() {
- *          co_await inner();   // continuation_ links outer -> inner
- *          co_return;          // FinalAwaiter resumes outer
- *      }
- *
- * 3. Exceptions propagate through co_await:
- *
- *      CoroTask<void> failing() {
- *          throw std::runtime_error("oops");
- *          co_return;
- *      }
- *      CoroTask<void> caller() {
- *          try { co_await failing(); }
- *          catch (std::runtime_error const&) { // caught here }
- *      }
- *
- * Caveats / Pitfalls
- * ==================
- *
- * BUG-RISK: Dangling references in coroutine parameters.
- *   Coroutine parameters are copied into the frame, but references
- *   are NOT -- they are stored as-is. If the referent goes out of scope
- *   before the coroutine finishes, you get use-after-free.
- *
- *      // BROKEN -- local dies before coroutine runs:
- *      CoroTask<void> bad(int& ref) { co_return; }
- *      void launch() {
- *          int local = 42;
- *          auto task = bad(local);  // frame stores &local
- *      }  // local destroyed; frame holds dangling ref
- *
- *      // FIX -- pass by value, or ensure lifetime via shared_ptr.
- *
- * BUG-RISK: GCC 14 corrupts reference captures in coroutine lambdas.
- *   When a lambda that returns CoroTask captures by reference ([&]),
- *   GCC 14 may generate a corrupted coroutine frame. Always capture
- *   by explicit pointer-to-value instead:
- *
- *      // BROKEN on GCC 14:
- *      jq.postCoroTask(t, n, [&](auto) -> CoroTask<void> { ... });
- *
- *      // FIX -- capture pointers explicitly:
- *      jq.postCoroTask(t, n, [ptr = &val](auto) -> CoroTask<void> { ... });
- *
- * BUG-RISK: Resuming a destroyed or completed CoroTask.
- *   Calling handle().resume() after the coroutine has already run to
- *   completion (done() == true) is undefined behavior. The CoroTaskRunner
- *   guards against this with an XRPL_ASSERT, but standalone usage of
- *   CoroTask must check done() before resuming.
- *
- * BUG-RISK: Moving a CoroTask that is being awaited.
- *   If task A is co_await-ed by task B (so A.continuation_ == B), moving
- *   or destroying A will invalidate the continuation link. Never move
- *   or reassign a CoroTask while it is mid-execution or being awaited.
- *
- * LIMITATION: CoroTask is fire-and-forget for the top-level owner.
- *   There is no built-in notification when the coroutine finishes.
- *   The caller must use external synchronization (e.g. CoroTaskRunner::join
- *   or a gate/condition_variable) to know when it is done.
- *
- * LIMITATION: No cancellation token.
- *   There is no way to cancel a suspended CoroTask from outside. The
- *   coroutine body must cooperatively check a flag (e.g. jq_.isStopping())
- *   after each co_await and co_return early if needed.
- *
- * LIMITATION: Stackless -- cannot suspend from nested non-coroutine calls.
- *   If a coroutine calls a regular function that wants to "yield", it
- *   cannot. Only the immediate coroutine body can use co_await.
- *   This is acceptable for rippled because all yield() sites are shallow.
- */
-template <>
-class CoroTask<void>
-{
-public:
-    struct promise_type;
-    using Handle = std::coroutine_handle<promise_type>;
-
-    /**
-     * Coroutine promise. Compiler uses this to manage coroutine state.
-     * Stores the exception (if any) and the continuation handle for
-     * symmetric transfer back to the awaiting coroutine.
-     */
-    struct promise_type
-    {
-        // Captured exception from the coroutine body, rethrown in
-        // await_resume() when this task is co_await-ed by a caller.
-        std::exception_ptr exception_;
-
-        // Handle to the coroutine that is co_await-ing this task.
-        // Set by await_suspend(). FinalAwaiter uses it for symmetric
-        // transfer back to the caller. Null if this is a top-level task.
-        std::coroutine_handle<> continuation_;
-
-        /**
-         * Create the CoroTask return object.
-         * Called by the compiler at coroutine creation.
-         */
-        CoroTask
-        get_return_object()
-        {
-            return CoroTask{Handle::from_promise(*this)};
-        }
-
-        /**
-         * Lazy start. The coroutine body does not execute until the
-         * handle is explicitly resumed (e.g. by CoroTaskRunner::resume).
-         */
-        std::suspend_always
-        initial_suspend() noexcept
-        {
-            return {};
-        }
-
-        /**
-         * Awaiter returned by final_suspend(). Uses symmetric transfer:
-         * if a continuation exists, transfers control directly to it
-         * (tail-call, no stack growth). Otherwise returns noop_coroutine
-         * so the coroutine frame stays alive for the owner to destroy.
-         */
-        struct FinalAwaiter
-        {
-            /**
-             * Always false. We need await_suspend to run for
-             * symmetric transfer.
-             */
-            bool
-            await_ready() noexcept
-            {
-                return false;
-            }
-
-            /**
-             * Symmetric transfer: returns the continuation handle so
-             * the compiler emits a tail-call instead of a nested resume.
-             * If no continuation is set, returns noop_coroutine to
-             * suspend at final_suspend without destroying the frame.
-             *
-             * @param h Handle to this completing coroutine
-             *
-             * @return Continuation handle, or noop_coroutine
-             */
-            std::coroutine_handle<>
-            await_suspend(Handle h) noexcept
-            {
-                if (auto cont = h.promise().continuation_)
-                    return cont;
-                return std::noop_coroutine();
-            }
-
-            void
-            await_resume() noexcept
-            {
-            }
-        };
-
-        /**
-         * Returns FinalAwaiter for symmetric transfer at coroutine end.
-         */
-        FinalAwaiter
-        final_suspend() noexcept
-        {
-            return {};
-        }
-
-        /**
-         * Called by the compiler for `co_return;` (void coroutine).
-         */
-        void
-        return_void()
-        {
-        }
-
-        /**
-         * Called by the compiler when an exception escapes the coroutine
-         * body. Captures it for later rethrowing in await_resume().
-         */
-        void
-        unhandled_exception()
-        {
-            exception_ = std::current_exception();
-        }
-    };
-
-    /**
-     * Default constructor. Creates an empty (null handle) task.
-     */
-    CoroTask() = default;
-
-    /**
-     * Takes ownership of a compiler-generated coroutine handle.
-     *
-     * @param h Coroutine handle to own
-     */
-    explicit CoroTask(Handle h) : handle_(h)
-    {
-    }
-
-    /**
-     * Destroys the coroutine frame if this task owns one.
-     */
-    ~CoroTask()
-    {
-        if (handle_)
-            handle_.destroy();
-    }
-
-    /**
-     * Move constructor. Transfers handle ownership, leaves other empty.
-     */
-    CoroTask(CoroTask&& other) noexcept : handle_(std::exchange(other.handle_, {}))
-    {
-    }
-
-    /**
-     * Move assignment. Destroys current frame (if any), takes other's.
-     */
-    CoroTask&
-    operator=(CoroTask&& other) noexcept
-    {
-        if (this != &other)
-        {
-            if (handle_)
-                handle_.destroy();
-            handle_ = std::exchange(other.handle_, {});
-        }
-        return *this;
-    }
-
-    CoroTask(CoroTask const&) = delete;
-    CoroTask&
-    operator=(CoroTask const&) = delete;
-
-    /**
-     * @return The underlying coroutine_handle
-     */
-    Handle
-    handle() const
-    {
-        return handle_;
-    }
-
-    /**
-     * @return true if the coroutine has run to completion (or thrown)
-     */
-    bool
-    done() const
-    {
-        return handle_ && handle_.done();
-    }
-
-    // -- Awaiter interface: allows `co_await someCoroTask;` --
-
-    /**
-     * Always false. This task is lazy, so co_await always suspends
-     * the caller to set up the continuation link.
-     */
-    bool
-    await_ready() const noexcept
-    {
-        return false;
-    }
-
-    /**
-     * Stores the caller's handle as our continuation, then returns
-     * our handle for symmetric transfer (caller suspends, we resume).
-     *
-     * @param caller Handle of the coroutine doing co_await on us
-     *
-     * @return Our handle for symmetric transfer
-     */
-    std::coroutine_handle<>
-    await_suspend(std::coroutine_handle<> caller) noexcept
-    {
-        handle_.promise().continuation_ = caller;
-        return handle_;  // Symmetric transfer
-    }
-
-    /**
-     * Called when the caller resumes after co_await. Rethrows any
-     * exception captured by unhandled_exception().
-     */
-    void
-    await_resume()
-    {
-        if (auto& ep = handle_.promise().exception_)
-            std::rethrow_exception(ep);
-    }
-
-private:
-    // Exclusively-owned coroutine handle. Null after move or default
-    // construction. Destroyed in the destructor.
-    Handle handle_;
-};
-
-/**
- * CoroTask<T> -- coroutine return type for value-returning coroutines.
- *
- * Class / Dependency Diagram
- * ==========================
- *
- *   CoroTask<T>
- *   +-----------------------------------------------+
- *   | - handle_ : Handle (coroutine_handle<promise>) |
- *   +-----------------------------------------------+
- *   | + handle(), done()                             |
- *   | + await_ready/suspend/resume  (Awaiter iface)  |
- *   +-----------------------------------------------+
- *            |  owns
- *            v
- *   promise_type
- *   +-----------------------------------------------+
- *   | - result_       : variant<monostate, T,        |
- *   |                           exception_ptr>       |
- *   | - continuation_ : std::coroutine_handle<>      |
- *   +-----------------------------------------------+
- *   | + get_return_object() -> CoroTask              |
- *   | + initial_suspend()   -> suspend_always (lazy) |
- *   | + final_suspend()     -> FinalAwaiter          |
- *   | + return_value(T)     -> stores in result_[1]  |
- *   | + unhandled_exception -> stores in result_[2]  |
- *   +-----------------------------------------------+
- *            |  returns at final_suspend
- *            v
- *   FinalAwaiter  (same symmetric-transfer pattern as CoroTask<void>)
- *
- * Value Extraction
- * ----------------
- * await_resume() inspects the variant:
- *   - index 2 (exception_ptr) -> rethrow
- *   - index 1 (T)             -> return value via move
- *
- * Usage Examples
- * ==============
- *
- * 1. Simple value return:
- *
- *      CoroTask<int> computeAnswer() { co_return 42; }
- *
- *      CoroTask<void> caller() {
- *          int v = co_await computeAnswer();  // v == 42
- *      }
- *
- * 2. Chaining value-returning coroutines:
- *
- *      CoroTask<int> add(int a, int b) { co_return a + b; }
- *      CoroTask<int> doubleSum(int a, int b) {
- *          int s = co_await add(a, b);
- *          co_return s * 2;
- *      }
- *
- * 3. Exception propagation from inner to outer:
- *
- *      CoroTask<int> failing() {
- *          throw std::runtime_error("bad");
- *          co_return 0;  // never reached
- *      }
- *      CoroTask<void> caller() {
- *          try {
- *              int v = co_await failing();  // throws here
- *          } catch (std::runtime_error const& e) {
- *              // e.what() == "bad"
- *          }
- *      }
- *
- * Caveats / Pitfalls (in addition to CoroTask<void> caveats above)
- * ================================================================
- *
- * BUG-RISK: await_resume() moves the value out of the variant.
- *   Calling co_await on the same CoroTask<T> instance twice is undefined
- *   behavior -- the second call will see a moved-from T. CoroTask is
- *   single-shot: one co_return, one co_await.
- *
- * BUG-RISK: T must be move-constructible.
- *   return_value(T) takes by value and moves into the variant.
- *   Types that are not movable cannot be used as T.
- *
- * LIMITATION: No co_yield support.
- *   CoroTask<T> only supports a single co_return. It does not implement
- *   yield_value(), so using co_yield inside a CoroTask<T> coroutine is a
- *   compile error. For streaming values, a different return type
- *   (e.g. Generator<T>) would be needed.
- *
- * LIMITATION: Result is only accessible via co_await.
- *   There is no .get() or .result() method. The value can only be
- *   extracted by co_await-ing the CoroTask<T> from inside another
- *   coroutine. For extracting results in non-coroutine code, pass a
- *   pointer to the caller and write through it (as the tests do).
- */
-template <typename T>
-class CoroTask
-{
-public:
-    struct promise_type;
-    using Handle = std::coroutine_handle<promise_type>;
-
-    /**
-     * Coroutine promise for value-returning coroutines.
-     * Stores the result as a variant: monostate (not yet set),
-     * T (co_return value), or exception_ptr (unhandled exception).
-     */
-    struct promise_type
-    {
-        // Tri-state result:
-        //   index 0 (monostate) -- coroutine has not yet completed
-        //   index 1 (T)         -- co_return value stored here
-        //   index 2 (exception) -- unhandled exception captured here
-        std::variant<std::monostate, T, std::exception_ptr> result_;
-
-        // Handle to the coroutine co_await-ing this task. Used by
-        // FinalAwaiter for symmetric transfer. Null for top-level tasks.
-        std::coroutine_handle<> continuation_;
-
-        /**
-         * Create the CoroTask return object.
-         * Called by the compiler at coroutine creation.
-         */
-        CoroTask
-        get_return_object()
-        {
-            return CoroTask{Handle::from_promise(*this)};
-        }
-
-        /**
-         * Lazy start. Coroutine body does not run until explicitly resumed.
-         */
-        std::suspend_always
-        initial_suspend() noexcept
-        {
-            return {};
-        }
-
-        /**
-         * Symmetric-transfer awaiter at coroutine completion.
-         * Same pattern as CoroTask<void>::FinalAwaiter.
-         */
-        struct FinalAwaiter
-        {
-            bool
-            await_ready() noexcept
-            {
-                return false;
-            }
-
-            /**
-             * Returns continuation for symmetric transfer, or
-             * noop_coroutine if this is a top-level task.
-             *
-             * @param h Handle to this completing coroutine
-             *
-             * @return Continuation handle, or noop_coroutine
-             */
-            std::coroutine_handle<>
-            await_suspend(Handle h) noexcept
-            {
-                if (auto cont = h.promise().continuation_)
-                    return cont;
-                return std::noop_coroutine();
-            }
-
-            void
-            await_resume() noexcept
-            {
-            }
-        };
-
-        FinalAwaiter
-        final_suspend() noexcept
-        {
-            return {};
-        }
-
-        /**
-         * Called by the compiler for `co_return value;`.
-         * Moves the value into result_ at index 1.
-         *
-         * @param value The value to store
-         */
-        void
-        return_value(T value)
-        {
-            result_.template emplace<1>(std::move(value));
-        }
-
-        /**
-         * Captures unhandled exceptions at index 2 of result_.
-         * Rethrown later in await_resume().
-         */
-        void
-        unhandled_exception()
-        {
-            result_.template emplace<2>(std::current_exception());
-        }
-    };
-
-    /**
-     * Default constructor. Creates an empty (null handle) task.
-     */
-    CoroTask() = default;
-
-    /**
-     * Takes ownership of a compiler-generated coroutine handle.
-     *
-     * @param h Coroutine handle to own
-     */
-    explicit CoroTask(Handle h) : handle_(h)
-    {
-    }
-
-    /**
-     * Destroys the coroutine frame if this task owns one.
-     */
-    ~CoroTask()
-    {
-        if (handle_)
-            handle_.destroy();
-    }
-
-    /**
-     * Move constructor. Transfers handle ownership, leaves other empty.
-     */
-    CoroTask(CoroTask&& other) noexcept : handle_(std::exchange(other.handle_, {}))
-    {
-    }
-
-    /**
-     * Move assignment. Destroys current frame (if any), takes other's.
-     */
-    CoroTask&
-    operator=(CoroTask&& other) noexcept
-    {
-        if (this != &other)
-        {
-            if (handle_)
-                handle_.destroy();
-            handle_ = std::exchange(other.handle_, {});
-        }
-        return *this;
-    }
-
-    CoroTask(CoroTask const&) = delete;
-    CoroTask&
-    operator=(CoroTask const&) = delete;
-
-    /**
-     * @return The underlying coroutine_handle
-     */
-    Handle
-    handle() const
-    {
-        return handle_;
-    }
-
-    /**
-     * @return true if the coroutine has run to completion (or thrown)
-     */
-    bool
-    done() const
-    {
-        return handle_ && handle_.done();
-    }
-
-    // -- Awaiter interface: allows `T val = co_await someCoroTask;` --
-
-    /**
-     * Always false. co_await always suspends to set up continuation.
-     */
-    bool
-    await_ready() const noexcept
-    {
-        return false;
-    }
-
-    /**
-     * Stores caller as continuation, returns our handle for
-     * symmetric transfer.
-     *
-     * @param caller Handle of the coroutine doing co_await on us
-     *
-     * @return Our handle for symmetric transfer
-     */
-    std::coroutine_handle<>
-    await_suspend(std::coroutine_handle<> caller) noexcept
-    {
-        handle_.promise().continuation_ = caller;
-        return handle_;
-    }
-
-    /**
-     * Extracts the result: rethrows if exception, otherwise moves
-     * the T value out of the variant. Single-shot: calling twice
-     * on the same task is undefined (moved-from T).
-     *
-     * @return The co_return-ed value
-     */
-    T
-    await_resume()
-    {
-        auto& result = handle_.promise().result_;
-        if (auto* ep = std::get_if<2>(&result))
-            std::rethrow_exception(*ep);
-        return std::get<1>(std::move(result));
-    }
-
-private:
-    // Exclusively-owned coroutine handle. Null after move or default
-    // construction. Destroyed in the destructor.
-    Handle handle_;
-};
-
-}  // namespace xrpl

include/xrpl/core/CoroTaskRunner.ipp

@@ -1,321 +0,0 @@
-#pragma once
-
-/**
- * @file CoroTaskRunner.ipp
- *
- * CoroTaskRunner inline implementation.
- *
- * This file contains the business logic for managing C++20 coroutines
- * on the JobQueue. It is included at the bottom of JobQueue.h.
- *
- * Data Flow: suspend / post / resume cycle
- * =========================================
- *
- *         coroutine body                 CoroTaskRunner              JobQueue
- *         --------------                 --------------              --------
- *              |
- *    co_await runner->suspend()
- *              |
- *              +--- await_suspend ------> onSuspend()
- *              |                            ++nSuspend_ ------------> nSuspend_
- *              |                          [coroutine is now suspended]
- *              |
- *              .    (externally or by JobQueueAwaiter)
- *              .
- *              +--- (caller calls) -----> post()
- *              |                            running_ = true
- *              |                            addJob(resume) ----------> job enqueued
- *              |                                                        |
- *              |                                                      [worker picks up]
- *              |                                                        |
- *              +--- <----- resume() <-----------------------------------+
- *              |             --nSuspend_ ------> nSuspend_
- *              |             swap in LocalValues (lvs_)
- *              |             task_.handle().resume()
- *              |                |
- *              |    [coroutine body continues here]
- *              |                |
- *              |             swap out LocalValues
- *              |             running_ = false
- *              |             cv_.notify_all()
- *              v
- *
- * Thread Safety
- * =============
- * - mutex_     : guards task_.handle().resume() so that post()-before-suspend
- *                races cannot resume the coroutine while it is still running.
- *                (See the race condition discussion in JobQueue.h)
- * - mutex_run_ : guards running_ flag; used by join() to wait for completion.
- * - jq_.m_mutex: guards nSuspend_ increments/decrements.
- *
- * Common Mistakes When Modifying This File
- * =========================================
- *
- * 1. Changing lock ordering.
- *    resume() acquires locks in this order: mutex_run_ -> jq_.m_mutex -> mutex_.
- *    Acquiring them in a different order WILL deadlock. Any new code path
- *    that touches these mutexes must follow the same order.
- *
- * 2. Removing the shared_from_this() capture in post().
- *    The lambda passed to addJob captures [this, sp = shared_from_this()].
- *    If you remove sp, 'this' can be destroyed before the job runs,
- *    causing use-after-free. The sp capture is load-bearing.
- *
- * 3. Forgetting to decrement nSuspend_ on a new code path.
- *    Every ++nSuspend_ must have a matching --nSuspend_. If you add a new
- *    suspension path (e.g. a new awaiter) and forget to decrement on resume
- *    or on failure, JobQueue::stop() will hang.
- *
- * 4. Calling task_.handle().resume() without holding mutex_.
- *    This allows a race where the coroutine runs on two threads
- *    simultaneously. Always hold mutex_ around resume().
- *
- * 5. Swapping LocalValues outside of the mutex_ critical section.
- *    The swap-in and swap-out of LocalValues must bracket the resume()
- *    call. If you move the swap-out before the lock_guard(mutex_) is
- *    released, you break LocalValue isolation for any code that runs
- *    after the coroutine suspends but before the lock is dropped.
- */
-//
-
-namespace xrpl {
-
-/**
- * Construct a CoroTaskRunner. Sets running_ to false; does not
- * create the coroutine. Call init() afterwards.
- *
- * @param jq   The JobQueue this coroutine will run on
- * @param type Job type for scheduling priority
- * @param name Human-readable name for logging
- */
-inline JobQueue::CoroTaskRunner::CoroTaskRunner(
-    create_t,
-    JobQueue& jq,
-    JobType type,
-    std::string const& name)
-    : jq_(jq), type_(type), name_(name), running_(false)
-{
-}
-
-/**
- * Initialize with a coroutine-returning callable.
- * Stores the callable on the heap (FuncStore) so it outlives the
- * coroutine frame. Coroutine frames store a reference to the
- * callable's implicit object parameter (the lambda). If the callable
- * is a temporary, that reference dangles after the caller returns.
- * Keeping the callable alive here ensures the coroutine's captures
- * remain valid.
- *
- * @param f Callable: CoroTask<void>(shared_ptr<CoroTaskRunner>)
- */
-template <class F>
-void
-JobQueue::CoroTaskRunner::init(F&& f)
-{
-    using Fn = std::decay_t<F>;
-    auto store = std::make_unique<FuncStore<Fn>>(std::forward<F>(f));
-    task_ = store->func(shared_from_this());
-    storedFunc_ = std::move(store);
-}
-
-/**
- * Destructor. Asserts (debug) that the coroutine has finished
- * or expectEarlyExit() was called.
- */
-inline JobQueue::CoroTaskRunner::~CoroTaskRunner()
-{
-#ifndef NDEBUG
-    XRPL_ASSERT(finished_, "xrpl::JobQueue::CoroTaskRunner::~CoroTaskRunner : is finished");
-#endif
-}
-
-/**
- * Increment the JobQueue's suspended-coroutine count (nSuspend_).
- */
-inline void
-JobQueue::CoroTaskRunner::onSuspend()
-{
-    std::lock_guard lock(jq_.m_mutex);
-    ++jq_.nSuspend_;
-}
-
-/**
- * Decrement nSuspend_ without resuming.
- */
-inline void
-JobQueue::CoroTaskRunner::onUndoSuspend()
-{
-    std::lock_guard lock(jq_.m_mutex);
-    --jq_.nSuspend_;
-}
-
-/**
- * Return a SuspendAwaiter whose await_suspend() increments nSuspend_
- * before the coroutine actually suspends. The caller must later call
- * post() or resume() to continue execution.
- *
- * @return Awaiter for use with `co_await runner->suspend()`
- */
-inline auto
-JobQueue::CoroTaskRunner::suspend()
-{
-    /**
-     * Custom awaiter for suspend(). Always suspends (await_ready
-     * returns false) and increments nSuspend_ in await_suspend().
-     */
-    struct SuspendAwaiter
-    {
-        CoroTaskRunner& runner_;  // The runner that owns this coroutine.
-
-        /**
-         * Always returns false so the coroutine suspends.
-         */
-        bool
-        await_ready() const noexcept
-        {
-            return false;
-        }
-
-        /**
-         * Called when the coroutine suspends. Increments nSuspend_
-         * so the JobQueue knows a coroutine is waiting.
-         */
-        void
-        await_suspend(std::coroutine_handle<>) const
-        {
-            runner_.onSuspend();
-        }
-
-        void
-        await_resume() const noexcept
-        {
-        }
-    };
-    return SuspendAwaiter{*this};
-}
-
-/**
- * Schedule coroutine resumption as a job on the JobQueue.
- * A shared_ptr capture (sp) prevents this CoroTaskRunner from being
- * destroyed while the job is queued but not yet executed.
- *
- * @return false if the JobQueue rejected the job (shutting down)
- */
-inline bool
-JobQueue::CoroTaskRunner::post()
-{
-    {
-        std::lock_guard lk(mutex_run_);
-        running_ = true;
-    }
-
-    // sp prevents 'this' from being destroyed while the job is pending
-    if (jq_.addJob(type_, name_, [this, sp = shared_from_this()]() { resume(); }))
-    {
-        return true;
-    }
-
-    // The coroutine will not run. Clean up running_.
-    std::lock_guard lk(mutex_run_);
-    running_ = false;
-    cv_.notify_all();
-    return false;
-}
-
-/**
- * Resume the coroutine on the current thread.
- *
- * Steps:
- *   1. Set running_ = true (under mutex_run_)
- *   2. Decrement nSuspend_ (under jq_.m_mutex)
- *   3. Swap in this coroutine's LocalValues for thread-local isolation
- *   4. Resume the coroutine handle (under mutex_)
- *   5. Swap out LocalValues, restoring the thread's previous state
- *   6. Set running_ = false and notify join() waiters
- */
-inline void
-JobQueue::CoroTaskRunner::resume()
-{
-    {
-        std::lock_guard lk(mutex_run_);
-        running_ = true;
-    }
-    {
-        std::lock_guard lock(jq_.m_mutex);
-        --jq_.nSuspend_;
-    }
-    auto saved = detail::getLocalValues().release();
-    detail::getLocalValues().reset(&lvs_);
-    std::lock_guard lock(mutex_);
-    XRPL_ASSERT(!task_.done(), "xrpl::JobQueue::CoroTaskRunner::resume : task is not done");
-    task_.handle().resume();
-    detail::getLocalValues().release();
-    detail::getLocalValues().reset(saved);
-    if (task_.done())
-    {
-#ifndef NDEBUG
-        finished_ = true;
-#endif
-        // Break the shared_ptr cycle: frame -> shared_ptr<runner> -> this.
-        // Use std::move (not task_ = {}) so task_.handle_ is null BEFORE the
-        // frame is destroyed. operator= would destroy the frame while handle_
-        // still holds the old value -- a re-entrancy hazard on GCC-12 if
-        // frame destruction triggers runner cleanup.
-        [[maybe_unused]] auto completed = std::move(task_);
-    }
-    std::lock_guard lk(mutex_run_);
-    running_ = false;
-    cv_.notify_all();
-}
-
-/**
- * @return true if the coroutine has not yet run to completion
- */
-inline bool
-JobQueue::CoroTaskRunner::runnable() const
-{
-    // After normal completion, task_ is reset to break the shared_ptr cycle
-    // (handle_ becomes null). A null handle means the coroutine is done.
-    return task_.handle() && !task_.done();
-}
-
-/**
- * Handle early termination when the coroutine never ran (e.g. JobQueue
- * is stopping). Decrements nSuspend_ and destroys the coroutine frame
- * to break the shared_ptr cycle: frame -> lambda -> runner -> frame.
- */
-inline void
-JobQueue::CoroTaskRunner::expectEarlyExit()
-{
-#ifndef NDEBUG
-    if (!finished_)
-#endif
-    {
-        std::lock_guard lock(jq_.m_mutex);
-        --jq_.nSuspend_;
-#ifndef NDEBUG
-        finished_ = true;
-#endif
-    }
-    // Break the shared_ptr cycle: frame -> shared_ptr<runner> -> this.
-    // The coroutine is at initial_suspend and never ran user code, so
-    // destroying it is safe. Use std::move (not task_ = {}) so
-    // task_.handle_ is null before the frame is destroyed.
-    {
-        [[maybe_unused]] auto completed = std::move(task_);
-    }
-    storedFunc_.reset();
-}
-
-/**
- * Block until the coroutine finishes its current execution slice.
- * Uses cv_ + mutex_run_ to wait until running_ == false.
- */
-inline void
-JobQueue::CoroTaskRunner::join()
-{
-    std::unique_lock<std::mutex> lk(mutex_run_);
-    cv_.wait(lk, [this]() { return running_ == false; });
-}
-
-}  // namespace xrpl

include/xrpl/core/JobQueue.h

@@ -2,13 +2,13 @@
 
 #include <xrpl/basics/LocalValue.h>
 #include <xrpl/core/ClosureCounter.h>
-#include <xrpl/core/CoroTask.h>
 #include <xrpl/core/JobTypeData.h>
 #include <xrpl/core/JobTypes.h>
 #include <xrpl/core/detail/Workers.h>
 #include <xrpl/json/json_value.h>
 
-#include <coroutine>
+#include <boost/coroutine/all.hpp>
+
 #include <set>
 
 namespace xrpl {
@@ -18,6 +18,10 @@ class PerfLog;
 }
 
 class Logs;
+struct Coro_create_t
+{
+    explicit Coro_create_t() = default;
+};
 
 /** A pool of threads to perform work.
 
@@ -32,380 +36,85 @@ class Logs;
 class JobQueue : private Workers::Callback
 {
 public:
-    /** C++20 coroutine lifecycle manager.
-     *
-     *  Class / Inheritance / Dependency Diagram
-     *  =========================================
-     *
-     *  std::enable_shared_from_this<CoroTaskRunner>
-     *            ^
-     *            | (public inheritance)
-     *            |
-     *  CoroTaskRunner
-     *  +---------------------------------------------------+
-     *  | - lvs_         : detail::LocalValues               |
-     *  | - jq_          : JobQueue&                         |
-     *  | - type_        : JobType                           |
-     *  | - name_        : std::string                       |
-     *  | - running_     : bool                              |
-     *  | - mutex_       : std::mutex      (coroutine guard) |
-     *  | - mutex_run_   : std::mutex      (join guard)      |
-     *  | - cv_          : condition_variable                 |
-     *  | - task_        : CoroTask<void>                    |
-     *  | - storedFunc_  : unique_ptr<FuncBase> (type-erased)|
-     *  +---------------------------------------------------+
-     *  | + init(F&&)         : set up coroutine callable    |
-     *  | + onSuspend()       : ++jq_.nSuspend_              |
-     *  | + onUndoSuspend()   : --jq_.nSuspend_              |
-     *  | + suspend()         : returns SuspendAwaiter       |
-     *  | + post()            : schedule resume on JobQueue  |
-     *  | + resume()          : resume coroutine on caller   |
-     *  | + runnable()        : !task_.done()                |
-     *  | + expectEarlyExit() : teardown for failed post     |
-     *  | + join()            : block until not running       |
-     *  +---------------------------------------------------+
-     *          |                          |
-     *          | owns                     | references
-     *          v                          v
-     *    CoroTask<void>             JobQueue
-     *    (coroutine frame)          (thread pool + nSuspend_)
-     *
-     *    FuncBase / FuncStore<F>    (type-erased heap storage
-     *                                for the coroutine lambda)
-     *
-     *  Coroutine Lifecycle (Control Flow)
-     *  ===================================
-     *
-     *  Caller thread              JobQueue worker thread
-     *  -------------              ----------------------
-     *  postCoroTask(f)
-     *    |
-     *    +-- check stopping_ (reject if JQ shutting down)
-     *    +-- ++nSuspend_  (lazy start counts as suspended)
-     *    +-- make_shared<CoroTaskRunner>
-     *    +-- init(f)
-     *    |     +-- store lambda on heap (FuncStore)
-     *    |     +-- task_ = f(shared_from_this())
-     *    |           [coroutine created, suspended at initial_suspend]
-     *    +-- resume()   (synchronous — runs on caller's thread)
-     *    |     +-- running_ = true
-     *    |     +-- --nSuspend_
-     *    |     +-- swap in LocalValues
-     *    |     +-- task_.handle().resume()
-     *    |     |     [coroutine body runs to first co_await or co_return]
-     *    |     |     ...
-     *    |     |     co_await suspend()
-     *    |     |       +-- ++nSuspend_
-     *    |     |       [coroutine suspends]
-     *    |     +-- swap out LocalValues
-     *    |     +-- running_ = false
-     *    |     +-- cv_.notify_all()
-     *    |
-     *  post()  <-- called externally or by JobQueueAwaiter
-     *    +-- addJob(type_, [resume]{})
-     *                                         resume()
-     *                                           |
-     *                                           +-- [coroutine body continues]
-     *                                           +-- co_return
-     *                                           +-- running_ = false
-     *                                           +-- cv_.notify_all()
-     *  join()
-     *    +-- cv_.wait([]{!running_})
-     *    +-- [done]
-     *
-     *  Usage Examples
-     *  ==============
-     *
-     *  1. Fire-and-forget coroutine (most common pattern):
-     *
-     *      jq.postCoroTask(jtCLIENT, "MyWork",
-     *          [](auto runner) -> CoroTask<void> {
-     *              doSomeWork();
-     *              co_await runner->suspend();  // yield to other jobs
-     *              doMoreWork();
-     *              co_return;
-     *          });
-     *
-     *  2. Manually controlling suspend / resume (external trigger):
-     *
-     *      auto runner = jq.postCoroTask(jtCLIENT, "ExtTrigger",
-     *          [&result](auto runner) -> CoroTask<void> {
-     *              startAsyncOperation(callback);
-     *              co_await runner->suspend();
-     *              // callback called runner->post() to get here
-     *              result = collectResult();
-     *              co_return;
-     *          });
-     *      // ... later, from the callback:
-     *      runner->post();   // reschedule the coroutine on the JobQueue
-     *
-     *  3. Using JobQueueAwaiter for automatic suspend + repost:
-     *
-     *      jq.postCoroTask(jtCLIENT, "AutoRepost",
-     *          [](auto runner) -> CoroTask<void> {
-     *              step1();
-     *              co_await JobQueueAwaiter{runner};  // yield + auto-repost
-     *              step2();
-     *              co_await JobQueueAwaiter{runner};
-     *              step3();
-     *              co_return;
-     *          });
-     *
-     *  4. Checking shutdown after co_await (cooperative cancellation):
-     *
-     *      jq.postCoroTask(jtCLIENT, "Cancellable",
-     *          [&jq](auto runner) -> CoroTask<void> {
-     *              while (moreWork()) {
-     *                  co_await JobQueueAwaiter{runner};
-     *                  if (jq.isStopping())
-     *                      co_return;  // bail out cleanly
-     *                  processNextItem();
-     *              }
-     *              co_return;
-     *          });
-     *
-     *  Caveats / Pitfalls
-     *  ==================
-     *
-     *  BUG-RISK: Calling suspend() without a matching post()/resume().
-     *    After co_await runner->suspend(), the coroutine is parked and
-     *    nSuspend_ is incremented.  If nothing ever calls post() or
-     *    resume(), the coroutine is leaked and JobQueue::stop() will
-     *    hang forever waiting for nSuspend_ to reach zero.
-     *
-     *  BUG-RISK: Calling post() on an already-running coroutine.
-     *    post() schedules a resume() job.  If the coroutine has not
-     *    actually suspended yet (no co_await executed), the resume job
-     *    will try to call handle().resume() while the coroutine is still
-     *    running on another thread.  This is UB.  The mutex_ prevents
-     *    data corruption but the logic is wrong — always co_await
-     *    suspend() before calling post().  (The test testIncorrectOrder
-     *    shows this works only because mutex_ serializes the calls.)
-     *
-     *  BUG-RISK: Dropping the shared_ptr<CoroTaskRunner> before join().
-     *    The CoroTaskRunner destructor asserts (!finished_ is false).
-     *    If you let the last shared_ptr die while the coroutine is still
-     *    running or suspended, you get an assertion failure in debug and
-     *    UB in release.  Always call join() or expectEarlyExit() first.
-     *
-     *  BUG-RISK: Lambda captures outliving the coroutine frame.
-     *    The lambda passed to postCoroTask is heap-allocated (FuncStore)
-     *    to prevent dangling.  But objects captured by pointer still need
-     *    their own lifetime management.  If you capture a raw pointer to
-     *    a stack variable, and the stack frame exits before the coroutine
-     *    finishes, the pointer dangles.  Use shared_ptr or ensure the
-     *    pointed-to object outlives the coroutine.
-     *
-     *  BUG-RISK: Forgetting co_return in a void coroutine.
-     *    If the coroutine body falls off the end without co_return,
-     *    the compiler may silently treat it as co_return (per standard),
-     *    but some compilers warn.  Always write explicit co_return.
-     *
-     *  LIMITATION: CoroTaskRunner only supports CoroTask<void>.
-     *    The task_ member is CoroTask<void>.  To return values from
-     *    the top-level coroutine, write through a captured pointer
-     *    (as the tests demonstrate), or co_await inner CoroTask<T>
-     *    coroutines that return values.
-     *
-     *  LIMITATION: One coroutine per CoroTaskRunner.
-     *    init() must be called exactly once.  You cannot reuse a
-     *    CoroTaskRunner to run a second coroutine.  Create a new one
-     *    via postCoroTask() instead.
-     *
-     *  LIMITATION: No timeout on join().
-     *    join() blocks indefinitely.  If the coroutine is suspended
-     *    and never posted, join() will deadlock.  Use timed waits
-     *    on the gate pattern (condition_variable + wait_for) in tests.
-     */
-    class CoroTaskRunner : public std::enable_shared_from_this<CoroTaskRunner>
+    /** Coroutines must run to completion. */
+    class Coro : public std::enable_shared_from_this<Coro>
     {
     private:
-        // Per-coroutine thread-local storage. Swapped in before resume()
-        // and swapped out after, so each coroutine sees its own LocalValue
-        // state regardless of which worker thread executes it.
         detail::LocalValues lvs_;
-
-        // Back-reference to the owning JobQueue. Used to post jobs,
-        // increment/decrement nSuspend_, and acquire jq_.m_mutex.
         JobQueue& jq_;
-
-        // Job type passed to addJob() when posting this coroutine.
         JobType type_;
-
-        // Human-readable name for this coroutine job (for logging).
         std::string name_;
-
-        // True while the coroutine is actively executing on a thread.
-        // Guarded by mutex_run_. join() blocks until this is false.
         bool running_;
-
-        // Guards task_.handle().resume() to prevent the coroutine from
-        // running on two threads simultaneously. Handles the race where
-        // post() enqueues a resume before the coroutine has actually
-        // suspended (post-before-suspend pattern).
         std::mutex mutex_;
-
-        // Guards running_ flag. Used with cv_ for join() to wait
-        // until the coroutine finishes its current execution slice.
         std::mutex mutex_run_;
-
-        // Notified when running_ transitions to false, allowing
-        // join() waiters to wake up.
         std::condition_variable cv_;
-
-        // The coroutine handle wrapper. Owns the coroutine frame.
-        // Set by init(), reset to empty by expectEarlyExit() on
-        // early termination.
-        CoroTask<void> task_;
-
-        /**
-         * Type-erased base for heap-stored callables.
-         * Prevents the coroutine lambda from being destroyed before
-         * the coroutine frame is done with it.
-         *
-         * @see FuncStore
-         */
-        struct FuncBase
-        {
-            virtual ~FuncBase() = default;
-        };
-
-        /**
-         * Concrete type-erased storage for a callable of type F.
-         * The coroutine frame stores a reference to the lambda's implicit
-         * object parameter. If the lambda is a temporary, that reference
-         * dangles after the call returns. FuncStore keeps it alive on
-         * the heap for the lifetime of the CoroTaskRunner.
-         */
-        template <class F>
-        struct FuncStore : FuncBase
-        {
-            F func;  // The stored callable (coroutine lambda).
-            explicit FuncStore(F&& f) : func(std::move(f))
-            {
-            }
-        };
-
-        // Heap-allocated callable storage. Set by init(), ensures the
-        // lambda outlives the coroutine frame that references it.
-        std::unique_ptr<FuncBase> storedFunc_;
-
+        boost::coroutines::asymmetric_coroutine<void>::pull_type coro_;
+        boost::coroutines::asymmetric_coroutine<void>::push_type* yield_;
 #ifndef NDEBUG
-        // Debug-only flag. True once the coroutine has completed or
-        // expectEarlyExit() was called. Asserted in the destructor
-        // to catch leaked runners.
         bool finished_ = false;
 #endif
 
     public:
-        /**
-         * Tag type for private construction. Prevents external code
-         * from constructing CoroTaskRunner directly. Use postCoroTask().
-         */
-        struct create_t
-        {
-            explicit create_t() = default;
-        };
-
-        /**
-         * Construct a CoroTaskRunner. Private by convention (create_t tag).
-         *
-         * @param jq   The JobQueue this coroutine will run on
-         * @param type Job type for scheduling priority
-         * @param name Human-readable name for logging
-         */
-        CoroTaskRunner(create_t, JobQueue&, JobType, std::string const&);
-
-        CoroTaskRunner(CoroTaskRunner const&) = delete;
-        CoroTaskRunner&
-        operator=(CoroTaskRunner const&) = delete;
-
-        /**
-         * Destructor. Asserts (debug) that the coroutine has finished
-         * or expectEarlyExit() was called.
-         */
-        ~CoroTaskRunner();
-
-        /**
-         * Initialize with a coroutine-returning callable.
-         * Must be called exactly once, after the object is managed by
-         * shared_ptr (because init uses shared_from_this internally).
-         * This is handled automatically by postCoroTask().
-         *
-         * @param f Callable: CoroTask<void>(shared_ptr<CoroTaskRunner>)
-         */
+        // Private: Used in the implementation
         template <class F>
+        Coro(Coro_create_t, JobQueue&, JobType, std::string const&, F&&);
+
+        // Not copy-constructible or assignable
+        Coro(Coro const&) = delete;
+        Coro&
+        operator=(Coro const&) = delete;
+
+        ~Coro();
+
+        /** Suspend coroutine execution.
+            Effects:
+              The coroutine's stack is saved.
+              The associated Job thread is released.
+            Note:
+              The associated Job function returns.
+              Undefined behavior if called consecutively without a corresponding
+           post.
+        */
         void
-        init(F&& f);
+        yield() const;
 
-        /**
-         * Increment the JobQueue's suspended-coroutine count (nSuspend_).
-         * Called when the coroutine is about to suspend. Every call
-         * must be balanced by a corresponding decrement (via resume()
-         * or onUndoSuspend()), or JobQueue::stop() will hang.
-         */
-        void
-        onSuspend();
+        /** Schedule coroutine execution.
+            Effects:
+              Returns immediately.
+              A new job is scheduled to resume the execution of the coroutine.
+              When the job runs, the coroutine's stack is restored and execution
+                continues at the beginning of coroutine function or the
+           statement after the previous call to yield. Undefined behavior if
+           called after the coroutine has completed with a return (as opposed to
+           a yield()). Undefined behavior if post() or resume() called
+           consecutively without a corresponding yield.
 
-        /**
-         * Decrement nSuspend_ without resuming.
-         * Used to undo onSuspend() when a scheduled post() fails
-         * (e.g. JobQueue is stopping).
-         */
-        void
-        onUndoSuspend();
-
-        /**
-         * Suspend the coroutine.
-         * The awaiter's await_suspend() increments nSuspend_ before the
-         * coroutine actually suspends. The caller must later call post()
-         * or resume() to continue execution.
-         *
-         * @return An awaiter for use with `co_await runner->suspend()`
-         */
-        auto
-        suspend();
-
-        /**
-         * Schedule coroutine resumption as a job on the JobQueue.
-         * Captures shared_from_this() to prevent this runner from being
-         * destroyed while the job is queued.
-         *
-         * @return true if the job was accepted; false if the JobQueue
-         *         is stopping (caller must handle cleanup)
-         */
+            @return true if the Coro's job is added to the JobQueue.
+        */
         bool
         post();
 
-        /**
-         * Resume the coroutine on the current thread.
-         * Decrements nSuspend_, swaps in LocalValues, resumes the
-         * coroutine handle, swaps out LocalValues, and notifies join()
-         * waiters. Lock ordering: mutex_run_ -> jq_.m_mutex -> mutex_.
-         */
+        /** Resume coroutine execution.
+            Effects:
+               The coroutine continues execution from where it last left off
+                 using this same thread.
+            Undefined behavior if called after the coroutine has completed
+              with a return (as opposed to a yield()).
+            Undefined behavior if resume() or post() called consecutively
+              without a corresponding yield.
+        */
         void
         resume();
 
-        /**
-         * @return true if the coroutine has not yet run to completion
-         */
+        /** Returns true if the Coro is still runnable (has not returned). */
         bool
         runnable() const;
 
-        /**
-         * Handle early termination when the coroutine never ran.
-         * Decrements nSuspend_ and destroys the coroutine frame to
-         * break the shared_ptr cycle (frame -> lambda -> runner -> frame).
-         * Called by postCoroTask() when post() fails.
-         */
+        /** Once called, the Coro allows early exit without an assert. */
         void
         expectEarlyExit();
 
-        /**
-         * Block until the coroutine finishes its current execution slice.
-         * Uses cv_ + mutex_run_ to wait until running_ == false.
-         * Warning: deadlocks if the coroutine is suspended and never posted.
-         */
+        /** Waits until coroutine returns from the user function. */
         void
         join();
     };
@@ -443,18 +152,18 @@ public:
         return false;
     }
 
-    /** Creates a C++20 coroutine and adds a job to the queue to run it.
+    /** Creates a coroutine and adds a job to the queue which will run it.
 
         @param t The type of job.
         @param name Name of the job.
-        @param f Callable with signature
-            CoroTask<void>(std::shared_ptr<CoroTaskRunner>).
+        @param f Has a signature of void(std::shared_ptr<Coro>). Called when the
+       job executes.
 
-        @return shared_ptr to posted CoroTaskRunner. nullptr if not successful.
+        @return shared_ptr to posted Coro.  nullptr if post was not successful.
     */
     template <class F>
-    std::shared_ptr<CoroTaskRunner>
-    postCoroTask(JobType t, std::string const& name, F&& f);
+    std::shared_ptr<Coro>
+    postCoro(JobType t, std::string const& name, F&& f);
 
     /** Jobs waiting at this priority.
      */
@@ -508,6 +217,8 @@ public:
     isStopped() const;
 
 private:
+    friend class Coro;
+
     using JobDataMap = std::map<JobType, JobTypeData>;
 
     beast::Journal m_journal;
@@ -608,70 +319,86 @@ private:
     getJobLimit(JobType type);
 };
 
+/*
+    An RPC command is received and is handled via ServerHandler(HTTP) or
+    Handler(websocket), depending on the connection type. The handler then calls
+    the JobQueue::postCoro() method to create a coroutine and run it at a later
+    point. This frees up the handler thread and allows it to continue handling
+    other requests while the RPC command completes its work asynchronously.
+
+    postCoro() creates a Coro object. When the Coro ctor is called, and its
+    coro_ member is initialized (a boost::coroutines::pull_type), execution
+    automatically passes to the coroutine, which we don't want at this point,
+    since we are still in the handler thread context. It's important to note
+   here that construction of a boost pull_type automatically passes execution to
+   the coroutine. A pull_type object automatically generates a push_type that is
+    passed as a parameter (do_yield) in the signature of the function the
+    pull_type was created with. This function is immediately called during coro_
+    construction and within it, Coro::yield_ is assigned the push_type
+    parameter (do_yield) address and called (yield()) so we can return execution
+    back to the caller's stack.
+
+    postCoro() then calls Coro::post(), which schedules a job on the job
+    queue to continue execution of the coroutine in a JobQueue worker thread at
+    some later time. When the job runs, we lock on the Coro::mutex_ and call
+    coro_ which continues where we had left off. Since we the last thing we did
+    in coro_ was call yield(), the next thing we continue with is calling the
+    function param f, that was passed into Coro ctor. It is within this
+    function body that the caller specifies what he would like to do while
+    running in the coroutine and allow them to suspend and resume execution.
+    A task that relies on other events to complete, such as path finding, calls
+    Coro::yield() to suspend its execution while waiting on those events to
+    complete and continue when signaled via the Coro::post() method.
+
+    There is a potential race condition that exists here where post() can get
+    called before yield() after f is called. Technically the problem only occurs
+    if the job that post() scheduled is executed before yield() is called.
+    If the post() job were to be executed before yield(), undefined behavior
+    would occur. The lock ensures that coro_ is not called again until we exit
+    the coroutine. At which point a scheduled resume() job waiting on the lock
+    would gain entry, harmlessly call coro_ and immediately return as we have
+    already completed the coroutine.
+
+    The race condition occurs as follows:
+
+        1- The coroutine is running.
+        2- The coroutine is about to suspend, but before it can do so, it must
+            arrange for some event to wake it up.
+        3- The coroutine arranges for some event to wake it up.
+        4- Before the coroutine can suspend, that event occurs and the
+   resumption of the coroutine is scheduled on the job queue. 5- Again, before
+   the coroutine can suspend, the resumption of the coroutine is dispatched. 6-
+   Again, before the coroutine can suspend, the resumption code runs the
+            coroutine.
+        The coroutine is now running in two threads.
+
+        The lock prevents this from happening as step 6 will block until the
+            lock is released which only happens after the coroutine completes.
+*/
+
 }  // namespace xrpl
 
-#include <xrpl/core/CoroTaskRunner.ipp>
+#include <xrpl/core/Coro.ipp>
 
 namespace xrpl {
 
-// postCoroTask — entry point for launching a C++20 coroutine on the JobQueue.
-//
-// Control Flow
-// ============
-//
-//   postCoroTask(t, name, f)
-//     |
-//     +-- 1. Check stopping_ — reject if JQ shutting down
-//     |
-//     +-- 2. ++nSuspend_   (mirrors Boost Coro ctor's implicit yield)
-//     |        The coroutine is "suspended" from the JobQueue's perspective
-//     |        even though it hasn't run yet — this keeps the JQ shutdown
-//     |        logic correct (it waits for nSuspend_ to reach 0).
-//     |
-//     +-- 3. Create CoroTaskRunner (shared_ptr, ref-counted)
-//     |
-//     +-- 4. runner->init(f)
-//     |        +-- Heap-allocate the lambda (FuncStore) to prevent
-//     |        |   dangling captures in the coroutine frame
-//     |        +-- task_ = f(shared_from_this())
-//     |              [coroutine created but NOT started — lazy initial_suspend]
-//     |
-//     +-- 5. runner->resume()   (synchronous — runs on caller's thread)
-//     |        +-- --nSuspend_
-//     |        +-- task_.handle().resume()
-//     |        |     [coroutine body runs until first co_await or co_return]
-//     |        +-- return runner to caller
-//
-// Why synchronous resume instead of async post()?
-// ================================================
-// The initial resume runs the coroutine body on the caller's thread to its
-// first suspension point (co_await) or completion (co_return). This matches
-// the behavioral pattern of the Boost Coro constructor, which ran coroutine
-// setup code synchronously. The synchronous approach ensures the coroutine
-// frame and its captured shared_ptr are in a determinate state before
-// postCoroTask returns, eliminating a class of non-deterministic lifetime
-// issues observed with async initial dispatch on GCC-12/15 debug builds.
-//
 template <class F>
-std::shared_ptr<JobQueue::CoroTaskRunner>
-JobQueue::postCoroTask(JobType t, std::string const& name, F&& f)
+std::shared_ptr<JobQueue::Coro>
+JobQueue::postCoro(JobType t, std::string const& name, F&& f)
 {
-    // Reject if the JQ is shutting down — matches addJob()'s stopping_ check.
-    // Must check before incrementing nSuspend_ to avoid leaving an orphan
-    // count that would cause stop() to hang.
-    if (stopping_)
-        return nullptr;
-
-    // Account for the initial suspension (CoroTask uses lazy start).
+    /*  First param is a detail type to make construction private.
+        Last param is the function the coroutine runs. Signature of
+        void(std::shared_ptr<Coro>).
+    */
+    auto coro = std::make_shared<Coro>(Coro_create_t{}, *this, t, name, std::forward<F>(f));
+    if (!coro->post())
     {
-        std::lock_guard lock(m_mutex);
-        ++nSuspend_;
+        // The Coro was not successfully posted.  Disable it so it's destructor
+        // can run with no negative side effects.  Then destroy it.
+        coro->expectEarlyExit();
+        coro.reset();
     }
-
-    auto runner = std::make_shared<CoroTaskRunner>(CoroTaskRunner::create_t{}, *this, t, name);
-    runner->init(std::forward<F>(f));
-    runner->resume();
-    return runner;
+    return coro;
 }
 
 }  // namespace xrpl

include/xrpl/core/JobQueueAwaiter.h

@@ -1,174 +0,0 @@
-#pragma once
-
-#include <xrpl/core/JobQueue.h>
-
-#include <coroutine>
-#include <memory>
-
-namespace xrpl {
-
-/**
- * Awaiter that suspends and immediately reschedules on the JobQueue.
- * Equivalent to calling yield() followed by post() in the old Coro API.
- *
- * Usage:
- *     co_await JobQueueAwaiter{runner};
- *
- * What it waits for: The coroutine is re-queued as a job and resumes
- * when a worker thread picks it up.
- *
- * Which thread resumes: A JobQueue worker thread.
- *
- * What await_resume() returns: void.
- *
- * Dependency Diagram
- * ==================
- *
- *   JobQueueAwaiter
- *   +----------------------------------------------+
- *   | + runner : shared_ptr<CoroTaskRunner>         |
- *   +----------------------------------------------+
- *   | + await_ready()   -> false (always suspend)   |
- *   | + await_suspend() -> bool (suspend or cancel) |
- *   | + await_resume()  -> void                     |
- *   +----------------------------------------------+
- *          |                         |
- *          | uses                    | uses
- *          v                         v
- *   CoroTaskRunner              JobQueue
- *   .onSuspend()                (via runner->post() -> addJob)
- *   .onUndoSuspend()
- *   .post()
- *
- * Control Flow (await_suspend)
- * ============================
- *
- *   co_await JobQueueAwaiter{runner}
- *     |
- *     +-- await_ready() -> false
- *     +-- await_suspend(handle)
- *           |
- *           +-- runner->onSuspend()     // ++nSuspend_
- *           +-- runner->post()          // addJob to JobQueue
- *           |     |
- *           |     +-- success? return true   // coroutine stays suspended
- *           |     |                          // worker thread will call resume()
- *           |     +-- failure? (JQ stopping)
- *           |           +-- runner->onUndoSuspend()  // --nSuspend_
- *           |           +-- return false   // coroutine continues immediately
- *           |                              // so it can clean up and co_return
- *
- * Usage Examples
- * ==============
- *
- * 1. Yield and auto-repost (most common -- replaces yield() + post()):
- *
- *     CoroTask<void> handler(auto runner) {
- *         doPartA();
- *         co_await JobQueueAwaiter{runner};  // yield + repost
- *         doPartB();                         // runs on a worker thread
- *         co_return;
- *     }
- *
- * 2. Multiple yield points in a loop:
- *
- *     CoroTask<void> batchProcessor(auto runner) {
- *         for (auto& item : items) {
- *             process(item);
- *             co_await JobQueueAwaiter{runner};  // let other jobs run
- *         }
- *         co_return;
- *     }
- *
- * 3. Graceful shutdown -- checking after resume:
- *
- *     CoroTask<void> longTask(auto runner, JobQueue& jq) {
- *         while (hasWork()) {
- *             co_await JobQueueAwaiter{runner};
- *             // If JQ is stopping, await_suspend returns false and
- *             // the coroutine continues immediately without re-queuing.
- *             // Always check isStopping() to decide whether to proceed:
- *             if (jq.isStopping())
- *                 co_return;
- *             doNextChunk();
- *         }
- *         co_return;
- *     }
- *
- * Caveats / Pitfalls
- * ==================
- *
- * BUG-RISK: Using a stale or null runner.
- *   The runner shared_ptr must be valid and point to the CoroTaskRunner
- *   that owns the coroutine currently executing. Passing a runner from
- *   a different coroutine, or a default-constructed shared_ptr, is UB.
- *
- * BUG-RISK: Assuming resume happens on the same thread.
- *   After co_await JobQueueAwaiter, the coroutine resumes on whatever
- *   worker thread picks up the job. Do not rely on thread-local state
- *   unless it is managed through LocalValue (which CoroTaskRunner
- *   automatically swaps in/out).
- *
- * BUG-RISK: Ignoring the shutdown path.
- *   When the JobQueue is stopping, post() fails and await_suspend()
- *   returns false (coroutine does NOT actually suspend). The coroutine
- *   body continues immediately on the same thread. If your code after
- *   co_await assumes it was re-queued and is running on a worker thread,
- *   that assumption breaks during shutdown. Always handle the "JQ is
- *   stopping" case, either by checking jq.isStopping() or by letting
- *   the coroutine fall through to co_return naturally.
- *
- * DIFFERENCE from runner->suspend() + runner->post():
- *   JobQueueAwaiter combines both in one atomic operation. With the
- *   manual suspend()/post() pattern, there is a window between the
- *   two calls where an external event could race. JobQueueAwaiter
- *   removes that window -- onSuspend() and post() happen within the
- *   same await_suspend() call while the coroutine is guaranteed to
- *   be suspended. Prefer JobQueueAwaiter unless you need an external
- *   party to decide *when* to call post().
- */
-struct JobQueueAwaiter
-{
-    // The CoroTaskRunner that owns the currently executing coroutine.
-    std::shared_ptr<JobQueue::CoroTaskRunner> runner;
-
-    /**
-     * Always returns false so the coroutine suspends.
-     */
-    bool
-    await_ready() const noexcept
-    {
-        return false;
-    }
-
-    /**
-     * Increment nSuspend (equivalent to yield()) and schedule resume
-     * on the JobQueue (equivalent to post()). If the JobQueue is
-     * stopping, undoes the suspend count and returns false so the
-     * coroutine continues immediately and can clean up.
-     *
-     * @return true if coroutine should stay suspended (job posted);
-     *         false if coroutine should continue (JQ stopping)
-     */
-    bool
-    await_suspend(std::coroutine_handle<>)
-    {
-        runner->onSuspend();
-        if (!runner->post())
-        {
-            // JobQueue is stopping. Undo the suspend count and
-            // don't actually suspend — the coroutine continues
-            // immediately so it can clean up and co_return.
-            runner->onUndoSuspend();
-            return false;
-        }
-        return true;
-    }
-
-    void
-    await_resume() const noexcept
-    {
-    }
-};
-
-}  // namespace xrpl

include/xrpl/tx/InvariantCheck.h

@@ -1,732 +0,0 @@
-#pragma once
-
-#include <xrpl/basics/Number.h>
-#include <xrpl/basics/base_uint.h>
-#include <xrpl/beast/utility/Journal.h>
-#include <xrpl/protocol/MPTIssue.h>
-#include <xrpl/protocol/STLedgerEntry.h>
-#include <xrpl/protocol/STTx.h>
-#include <xrpl/protocol/TER.h>
-
-#include <cstdint>
-#include <tuple>
-#include <unordered_set>
-
-namespace xrpl {
-
-class ReadView;
-
-#if GENERATING_DOCS
-/**
- * @brief Prototype for invariant check implementations.
- *
- * __THIS CLASS DOES NOT EXIST__ - or rather it exists in documentation only to
- * communicate the interface required of any invariant checker. Any invariant
- * check implementation should implement the public methods documented here.
- *
- */
-class InvariantChecker_PROTOTYPE
-{
-public:
-    explicit InvariantChecker_PROTOTYPE() = default;
-
-    /**
-     * @brief called for each ledger entry in the current transaction.
-     *
-     * @param isDelete true if the SLE is being deleted
-     * @param before ledger entry before modification by the transaction
-     * @param after ledger entry after modification by the transaction
-     */
-    void
-    visitEntry(
-        bool isDelete,
-        std::shared_ptr<SLE const> const& before,
-        std::shared_ptr<SLE const> const& after);
-
-    /**
-     * @brief called after all ledger entries have been visited to determine
-     * the final status of the check
-     *
-     * @param tx the transaction being applied
-     * @param tec the current TER result of the transaction
-     * @param fee the fee actually charged for this transaction
-     * @param view a ReadView of the ledger being modified
-     * @param j journal for logging
-     *
-     * @return true if check passes, false if it fails
-     */
-    bool
-    finalize(
-        STTx const& tx,
-        TER const tec,
-        XRPAmount const fee,
-        ReadView const& view,
-        beast::Journal const& j);
-};
-#endif
-
-/**
- * @brief Invariant: We should never charge a transaction a negative fee or a
- * fee that is larger than what the transaction itself specifies.
- *
- * We can, in some circumstances, charge less.
- */
-class TransactionFeeCheck
-{
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: A transaction must not create XRP and should only destroy
- * the XRP fee.
- *
- * We iterate through all account roots, payment channels and escrow entries
- * that were modified and calculate the net change in XRP caused by the
- * transactions.
- */
-class XRPNotCreated
-{
-    std::int64_t drops_ = 0;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: we cannot remove an account ledger entry
- *
- * We iterate all account roots that were modified, and ensure that any that
- * were present before the transaction was applied continue to be present
- * afterwards unless they were explicitly deleted by a successful
- * AccountDelete transaction.
- */
-class AccountRootsNotDeleted
-{
-    std::uint32_t accountsDeleted_ = 0;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: a deleted account must not have any objects left
- *
- * We iterate all deleted account roots, and ensure that there are no
- * objects left that are directly accessible with that account's ID.
- *
- * There should only be one deleted account, but that's checked by
- * AccountRootsNotDeleted. This invariant will handle multiple deleted account
- * roots without a problem.
- */
-class AccountRootsDeletedClean
-{
-    // Pair is <before, after>. Before is used for most of the checks, so that
-    // if, for example, an object ID field is cleared, but the object is not
-    // deleted, it can still be found. After is used specifically for any checks
-    // that are expected as part of the deletion, such as zeroing out the
-    // balance.
-    std::vector<std::pair<std::shared_ptr<SLE const>, std::shared_ptr<SLE const>>> accountsDeleted_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: An account XRP balance must be in XRP and take a value
- *                   between 0 and INITIAL_XRP drops, inclusive.
- *
- * We iterate all account roots modified by the transaction and ensure that
- * their XRP balances are reasonable.
- */
-class XRPBalanceChecks
-{
-    bool bad_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: corresponding modified ledger entries should match in type
- *                   and added entries should be a valid type.
- */
-class LedgerEntryTypesMatch
-{
-    bool typeMismatch_ = false;
-    bool invalidTypeAdded_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: Trust lines using XRP are not allowed.
- *
- * We iterate all the trust lines created by this transaction and ensure
- * that they are against a valid issuer.
- */
-class NoXRPTrustLines
-{
-    bool xrpTrustLine_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: Trust lines with deep freeze flag are not allowed if normal
- * freeze flag is not set.
- *
- * We iterate all the trust lines created by this transaction and ensure
- * that they don't have deep freeze flag set without normal freeze flag set.
- */
-class NoDeepFreezeTrustLinesWithoutFreeze
-{
-    bool deepFreezeWithoutFreeze_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: frozen trust line balance change is not allowed.
- *
- * We iterate all affected trust lines and ensure that they don't have
- * unexpected change of balance if they're frozen.
- */
-class TransfersNotFrozen
-{
-    struct BalanceChange
-    {
-        std::shared_ptr<SLE const> const line;
-        int const balanceChangeSign;
-    };
-
-    struct IssuerChanges
-    {
-        std::vector<BalanceChange> senders;
-        std::vector<BalanceChange> receivers;
-    };
-
-    using ByIssuer = std::map<Issue, IssuerChanges>;
-    ByIssuer balanceChanges_;
-
-    std::map<AccountID, std::shared_ptr<SLE const> const> possibleIssuers_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-
-private:
-    bool
-    isValidEntry(std::shared_ptr<SLE const> const& before, std::shared_ptr<SLE const> const& after);
-
-    STAmount
-    calculateBalanceChange(
-        std::shared_ptr<SLE const> const& before,
-        std::shared_ptr<SLE const> const& after,
-        bool isDelete);
-
-    void
-    recordBalance(Issue const& issue, BalanceChange change);
-
-    void
-    recordBalanceChanges(std::shared_ptr<SLE const> const& after, STAmount const& balanceChange);
-
-    std::shared_ptr<SLE const>
-    findIssuer(AccountID const& issuerID, ReadView const& view);
-
-    bool
-    validateIssuerChanges(
-        std::shared_ptr<SLE const> const& issuer,
-        IssuerChanges const& changes,
-        STTx const& tx,
-        beast::Journal const& j,
-        bool enforce);
-
-    bool
-    validateFrozenState(
-        BalanceChange const& change,
-        bool high,
-        STTx const& tx,
-        beast::Journal const& j,
-        bool enforce,
-        bool globalFreeze);
-};
-
-/**
- * @brief Invariant: offers should be for non-negative amounts and must not
- *                   be XRP to XRP.
- *
- * Examine all offers modified by the transaction and ensure that there are
- * no offers which contain negative amounts or which exchange XRP for XRP.
- */
-class NoBadOffers
-{
-    bool bad_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: an escrow entry must take a value between 0 and
- *                   INITIAL_XRP drops exclusive.
- */
-class NoZeroEscrow
-{
-    bool bad_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: a new account root must be the consequence of a payment,
- *                   must have the right starting sequence, and the payment
- *                   may not create more than one new account root.
- */
-class ValidNewAccountRoot
-{
-    std::uint32_t accountsCreated_ = 0;
-    std::uint32_t accountSeq_ = 0;
-    bool pseudoAccount_ = false;
-    std::uint32_t flags_ = 0;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: Validates several invariants for NFToken pages.
- *
- * The following checks are made:
- *  - The page is correctly associated with the owner.
- *  - The page is correctly ordered between the next and previous links.
- *  - The page contains at least one and no more than 32 NFTokens.
- *  - The NFTokens on this page do not belong on a lower or higher page.
- *  - The NFTokens are correctly sorted on the page.
- *  - Each URI, if present, is not empty.
- */
-class ValidNFTokenPage
-{
-    bool badEntry_ = false;
-    bool badLink_ = false;
-    bool badSort_ = false;
-    bool badURI_ = false;
-    bool invalidSize_ = false;
-    bool deletedFinalPage_ = false;
-    bool deletedLink_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: Validates counts of NFTokens after all transaction types.
- *
- * The following checks are made:
- *  - The number of minted or burned NFTokens can only be changed by
- *    NFTokenMint or NFTokenBurn transactions.
- *  - A successful NFTokenMint must increase the number of NFTokens.
- *  - A failed NFTokenMint must not change the number of minted NFTokens.
- *  - An NFTokenMint transaction cannot change the number of burned NFTokens.
- *  - A successful NFTokenBurn must increase the number of burned NFTokens.
- *  - A failed NFTokenBurn must not change the number of burned NFTokens.
- *  - An NFTokenBurn transaction cannot change the number of minted NFTokens.
- */
-class NFTokenCountTracking
-{
-    std::uint32_t beforeMintedTotal = 0;
-    std::uint32_t beforeBurnedTotal = 0;
-    std::uint32_t afterMintedTotal = 0;
-    std::uint32_t afterBurnedTotal = 0;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariant: Token holder's trustline balance cannot be negative after
- * Clawback.
- *
- * We iterate all the trust lines affected by this transaction and ensure
- * that no more than one trustline is modified, and also holder's balance is
- * non-negative.
- */
-class ValidClawback
-{
-    std::uint32_t trustlinesChanged = 0;
-    std::uint32_t mptokensChanged = 0;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-class ValidMPTIssuance
-{
-    std::uint32_t mptIssuancesCreated_ = 0;
-    std::uint32_t mptIssuancesDeleted_ = 0;
-
-    std::uint32_t mptokensCreated_ = 0;
-    std::uint32_t mptokensDeleted_ = 0;
-    // non-MPT transactions may attempt to create
-    // MPToken by an issuer
-    bool mptCreatedByIssuer_ = false;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariants: Permissioned Domains must have some rules and
- * AcceptedCredentials must have length between 1 and 10 inclusive.
- *
- * Since only permissions constitute rules, an empty credentials list
- * means that there are no rules and the invariant is violated.
- *
- * Credentials must be sorted and no duplicates allowed
- *
- */
-class ValidPermissionedDomain
-{
-    struct SleStatus
-    {
-        std::size_t credentialsSize_{0};
-        bool isSorted_ = false;
-        bool isUnique_ = false;
-        bool isDelete_ = false;
-    };
-    std::vector<SleStatus> sleStatus_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariants: Pseudo-accounts have valid and consistent properties
- *
- * Pseudo-accounts have certain properties, and some of those properties are
- * unique to pseudo-accounts. Check that all pseudo-accounts are following the
- * rules, and that only pseudo-accounts look like pseudo-accounts.
- *
- */
-class ValidPseudoAccounts
-{
-    std::vector<std::string> errors_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-class ValidPermissionedDEX
-{
-    bool regularOffers_ = false;
-    bool badHybrids_ = false;
-    hash_set<uint256> domains_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-class ValidAMM
-{
-    std::optional<AccountID> ammAccount_;
-    std::optional<STAmount> lptAMMBalanceAfter_;
-    std::optional<STAmount> lptAMMBalanceBefore_;
-    bool ammPoolChanged_;
-
-public:
-    enum class ZeroAllowed : bool { No = false, Yes = true };
-
-    ValidAMM() : ammPoolChanged_{false}
-    {
-    }
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-
-private:
-    bool
-    finalizeBid(bool enforce, beast::Journal const&) const;
-    bool
-    finalizeVote(bool enforce, beast::Journal const&) const;
-    bool
-    finalizeCreate(STTx const&, ReadView const&, bool enforce, beast::Journal const&) const;
-    bool
-    finalizeDelete(bool enforce, TER res, beast::Journal const&) const;
-    bool
-    finalizeDeposit(STTx const&, ReadView const&, bool enforce, beast::Journal const&) const;
-    // Includes clawback
-    bool
-    finalizeWithdraw(STTx const&, ReadView const&, bool enforce, beast::Journal const&) const;
-    bool
-    finalizeDEX(bool enforce, beast::Journal const&) const;
-    bool
-    generalInvariant(STTx const&, ReadView const&, ZeroAllowed zeroAllowed, beast::Journal const&)
-        const;
-};
-
-/**
- * @brief Invariants: Some fields are unmodifiable
- *
- * Check that any fields specified as unmodifiable are not modified when the
- * object is modified. Creation and deletion are ignored.
- *
- */
-class NoModifiedUnmodifiableFields
-{
-    // Pair is <before, after>.
-    std::set<std::pair<SLE::const_pointer, SLE::const_pointer>> changedEntries_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariants: Loan brokers are internally consistent
- *
- * 1. If `LoanBroker.OwnerCount = 0` the `DirectoryNode` will have at most one
- *    node (the root), which will only hold entries for `RippleState` or
- * `MPToken` objects.
- *
- */
-class ValidLoanBroker
-{
-    // Not all of these elements will necessarily be populated. Remaining items
-    // will be looked up as needed.
-    struct BrokerInfo
-    {
-        SLE::const_pointer brokerBefore = nullptr;
-        // After is used for most of the checks, except
-        // those that check changed values.
-        SLE::const_pointer brokerAfter = nullptr;
-    };
-    // Collect all the LoanBrokers found directly or indirectly through
-    // pseudo-accounts. Key is the brokerID / index. It will be used to find the
-    // LoanBroker object if brokerBefore and brokerAfter are nullptr
-    std::map<uint256, BrokerInfo> brokers_;
-    // Collect all the modified trust lines. Their high and low accounts will be
-    // loaded to look for LoanBroker pseudo-accounts.
-    std::vector<SLE::const_pointer> lines_;
-    // Collect all the modified MPTokens. Their accounts will be loaded to look
-    // for LoanBroker pseudo-accounts.
-    std::vector<SLE::const_pointer> mpts_;
-
-    bool
-    goodZeroDirectory(ReadView const& view, SLE::const_ref dir, beast::Journal const& j) const;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/**
- * @brief Invariants: Loans are internally consistent
- *
- * 1. If `Loan.PaymentRemaining = 0` then `Loan.PrincipalOutstanding = 0`
- *
- */
-class ValidLoan
-{
-    // Pair is <before, after>. After is used for most of the checks, except
-    // those that check changed values.
-    std::vector<std::pair<SLE::const_pointer, SLE::const_pointer>> loans_;
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-/*
- * @brief Invariants: Vault object and MPTokenIssuance for vault shares
- *
- * - vault deleted and vault created is empty
- * - vault created must be linked to pseudo-account for shares and assets
- * - vault must have MPTokenIssuance for shares
- * - vault without shares outstanding must have no shares
- * - loss unrealized does not exceed the difference between assets total and
- *   assets available
- * - assets available do not exceed assets total
- * - vault deposit increases assets and share issuance, and adds to:
- *   total assets, assets available, shares outstanding
- * - vault withdrawal and clawback reduce assets and share issuance, and
- *   subtracts from: total assets, assets available, shares outstanding
- * - vault set must not alter the vault assets or shares balance
- * - no vault transaction can change loss unrealized (it's updated by loan
- *   transactions)
- *
- */
-class ValidVault
-{
-    Number static constexpr zero{};
-
-    struct Vault final
-    {
-        uint256 key = beast::zero;
-        Asset asset = {};
-        AccountID pseudoId = {};
-        AccountID owner = {};
-        uint192 shareMPTID = beast::zero;
-        Number assetsTotal = 0;
-        Number assetsAvailable = 0;
-        Number assetsMaximum = 0;
-        Number lossUnrealized = 0;
-
-        Vault static make(SLE const&);
-    };
-
-    struct Shares final
-    {
-        MPTIssue share = {};
-        std::uint64_t sharesTotal = 0;
-        std::uint64_t sharesMaximum = 0;
-
-        Shares static make(SLE const&);
-    };
-
-    std::vector<Vault> afterVault_ = {};
-    std::vector<Shares> afterMPTs_ = {};
-    std::vector<Vault> beforeVault_ = {};
-    std::vector<Shares> beforeMPTs_ = {};
-    std::unordered_map<uint256, Number> deltas_ = {};
-
-public:
-    void
-    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
-
-    bool
-    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
-};
-
-// additional invariant checks can be declared above and then added to this
-// tuple
-using InvariantChecks = std::tuple<
-    TransactionFeeCheck,
-    AccountRootsNotDeleted,
-    AccountRootsDeletedClean,
-    LedgerEntryTypesMatch,
-    XRPBalanceChecks,
-    XRPNotCreated,
-    NoXRPTrustLines,
-    NoDeepFreezeTrustLinesWithoutFreeze,
-    TransfersNotFrozen,
-    NoBadOffers,
-    NoZeroEscrow,
-    ValidNewAccountRoot,
-    ValidNFTokenPage,
-    NFTokenCountTracking,
-    ValidClawback,
-    ValidMPTIssuance,
-    ValidPermissionedDomain,
-    ValidPermissionedDEX,
-    ValidAMM,
-    NoModifiedUnmodifiableFields,
-    ValidPseudoAccounts,
-    ValidLoanBroker,
-    ValidLoan,
-    ValidVault>;
-
-/**
- * @brief get a tuple of all invariant checks
- *
- * @return std::tuple of instances that implement the required invariant check
- * methods
- *
- * @see xrpl::InvariantChecker_PROTOTYPE
- */
-inline InvariantChecks
-getInvariantChecks()
-{
-    return InvariantChecks{};
-}
-
-}  // namespace xrpl

include/xrpl/tx/invariants/AMMInvariant.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <optional>
+
+namespace xrpl {
+
+class ValidAMM
+{
+    std::optional<AccountID> ammAccount_;
+    std::optional<STAmount> lptAMMBalanceAfter_;
+    std::optional<STAmount> lptAMMBalanceBefore_;
+    bool ammPoolChanged_;
+
+public:
+    enum class ZeroAllowed : bool { No = false, Yes = true };
+
+    ValidAMM() : ammPoolChanged_{false}
+    {
+    }
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+
+private:
+    bool
+    finalizeBid(bool enforce, beast::Journal const&) const;
+    bool
+    finalizeVote(bool enforce, beast::Journal const&) const;
+    bool
+    finalizeCreate(STTx const&, ReadView const&, bool enforce, beast::Journal const&) const;
+    bool
+    finalizeDelete(bool enforce, TER res, beast::Journal const&) const;
+    bool
+    finalizeDeposit(STTx const&, ReadView const&, bool enforce, beast::Journal const&) const;
+    // Includes clawback
+    bool
+    finalizeWithdraw(STTx const&, ReadView const&, bool enforce, beast::Journal const&) const;
+    bool
+    finalizeDEX(bool enforce, beast::Journal const&) const;
+    bool
+    generalInvariant(STTx const&, ReadView const&, ZeroAllowed zeroAllowed, beast::Journal const&)
+        const;
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/FreezeInvariant.h

@@ -0,0 +1,84 @@
+#pragma once
+
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/Issue.h>
+#include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <map>
+#include <vector>
+
+namespace xrpl {
+
+/**
+ * @brief Invariant: frozen trust line balance change is not allowed.
+ *
+ * We iterate all affected trust lines and ensure that they don't have
+ * unexpected change of balance if they're frozen.
+ */
+class TransfersNotFrozen
+{
+    struct BalanceChange
+    {
+        std::shared_ptr<SLE const> const line;
+        int const balanceChangeSign;
+    };
+
+    struct IssuerChanges
+    {
+        std::vector<BalanceChange> senders;
+        std::vector<BalanceChange> receivers;
+    };
+
+    using ByIssuer = std::map<Issue, IssuerChanges>;
+    ByIssuer balanceChanges_;
+
+    std::map<AccountID, std::shared_ptr<SLE const> const> possibleIssuers_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+
+private:
+    bool
+    isValidEntry(std::shared_ptr<SLE const> const& before, std::shared_ptr<SLE const> const& after);
+
+    STAmount
+    calculateBalanceChange(
+        std::shared_ptr<SLE const> const& before,
+        std::shared_ptr<SLE const> const& after,
+        bool isDelete);
+
+    void
+    recordBalance(Issue const& issue, BalanceChange change);
+
+    void
+    recordBalanceChanges(std::shared_ptr<SLE const> const& after, STAmount const& balanceChange);
+
+    std::shared_ptr<SLE const>
+    findIssuer(AccountID const& issuerID, ReadView const& view);
+
+    bool
+    validateIssuerChanges(
+        std::shared_ptr<SLE const> const& issuer,
+        IssuerChanges const& changes,
+        STTx const& tx,
+        beast::Journal const& j,
+        bool enforce);
+
+    bool
+    validateFrozenState(
+        BalanceChange const& change,
+        bool high,
+        STTx const& tx,
+        beast::Journal const& j,
+        bool enforce,
+        bool globalFreeze);
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/InvariantCheck.h

@@ -0,0 +1,385 @@
+#pragma once
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+#include <xrpl/tx/invariants/AMMInvariant.h>
+#include <xrpl/tx/invariants/FreezeInvariant.h>
+#include <xrpl/tx/invariants/LoanInvariant.h>
+#include <xrpl/tx/invariants/MPTInvariant.h>
+#include <xrpl/tx/invariants/NFTInvariant.h>
+#include <xrpl/tx/invariants/PermissionedDEXInvariant.h>
+#include <xrpl/tx/invariants/PermissionedDomainInvariant.h>
+#include <xrpl/tx/invariants/VaultInvariant.h>
+
+#include <cstdint>
+#include <tuple>
+
+namespace xrpl {
+
+#if GENERATING_DOCS
+/**
+ * @brief Prototype for invariant check implementations.
+ *
+ * __THIS CLASS DOES NOT EXIST__ - or rather it exists in documentation only to
+ * communicate the interface required of any invariant checker. Any invariant
+ * check implementation should implement the public methods documented here.
+ *
+ */
+class InvariantChecker_PROTOTYPE
+{
+public:
+    explicit InvariantChecker_PROTOTYPE() = default;
+
+    /**
+     * @brief called for each ledger entry in the current transaction.
+     *
+     * @param isDelete true if the SLE is being deleted
+     * @param before ledger entry before modification by the transaction
+     * @param after ledger entry after modification by the transaction
+     */
+    void
+    visitEntry(
+        bool isDelete,
+        std::shared_ptr<SLE const> const& before,
+        std::shared_ptr<SLE const> const& after);
+
+    /**
+     * @brief called after all ledger entries have been visited to determine
+     * the final status of the check
+     *
+     * @param tx the transaction being applied
+     * @param tec the current TER result of the transaction
+     * @param fee the fee actually charged for this transaction
+     * @param view a ReadView of the ledger being modified
+     * @param j journal for logging
+     *
+     * @return true if check passes, false if it fails
+     */
+    bool
+    finalize(
+        STTx const& tx,
+        TER const tec,
+        XRPAmount const fee,
+        ReadView const& view,
+        beast::Journal const& j);
+};
+#endif
+
+/**
+ * @brief Invariant: We should never charge a transaction a negative fee or a
+ * fee that is larger than what the transaction itself specifies.
+ *
+ * We can, in some circumstances, charge less.
+ */
+class TransactionFeeCheck
+{
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: A transaction must not create XRP and should only destroy
+ * the XRP fee.
+ *
+ * We iterate through all account roots, payment channels and escrow entries
+ * that were modified and calculate the net change in XRP caused by the
+ * transactions.
+ */
+class XRPNotCreated
+{
+    std::int64_t drops_ = 0;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: we cannot remove an account ledger entry
+ *
+ * We iterate all account roots that were modified, and ensure that any that
+ * were present before the transaction was applied continue to be present
+ * afterwards unless they were explicitly deleted by a successful
+ * AccountDelete transaction.
+ */
+class AccountRootsNotDeleted
+{
+    std::uint32_t accountsDeleted_ = 0;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: a deleted account must not have any objects left
+ *
+ * We iterate all deleted account roots, and ensure that there are no
+ * objects left that are directly accessible with that account's ID.
+ *
+ * There should only be one deleted account, but that's checked by
+ * AccountRootsNotDeleted. This invariant will handle multiple deleted account
+ * roots without a problem.
+ */
+class AccountRootsDeletedClean
+{
+    // Pair is <before, after>. Before is used for most of the checks, so that
+    // if, for example, an object ID field is cleared, but the object is not
+    // deleted, it can still be found. After is used specifically for any checks
+    // that are expected as part of the deletion, such as zeroing out the
+    // balance.
+    std::vector<std::pair<std::shared_ptr<SLE const>, std::shared_ptr<SLE const>>> accountsDeleted_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: An account XRP balance must be in XRP and take a value
+ *                   between 0 and INITIAL_XRP drops, inclusive.
+ *
+ * We iterate all account roots modified by the transaction and ensure that
+ * their XRP balances are reasonable.
+ */
+class XRPBalanceChecks
+{
+    bool bad_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: corresponding modified ledger entries should match in type
+ *                   and added entries should be a valid type.
+ */
+class LedgerEntryTypesMatch
+{
+    bool typeMismatch_ = false;
+    bool invalidTypeAdded_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: Trust lines using XRP are not allowed.
+ *
+ * We iterate all the trust lines created by this transaction and ensure
+ * that they are against a valid issuer.
+ */
+class NoXRPTrustLines
+{
+    bool xrpTrustLine_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: Trust lines with deep freeze flag are not allowed if normal
+ * freeze flag is not set.
+ *
+ * We iterate all the trust lines created by this transaction and ensure
+ * that they don't have deep freeze flag set without normal freeze flag set.
+ */
+class NoDeepFreezeTrustLinesWithoutFreeze
+{
+    bool deepFreezeWithoutFreeze_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: offers should be for non-negative amounts and must not
+ *                   be XRP to XRP.
+ *
+ * Examine all offers modified by the transaction and ensure that there are
+ * no offers which contain negative amounts or which exchange XRP for XRP.
+ */
+class NoBadOffers
+{
+    bool bad_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: an escrow entry must take a value between 0 and
+ *                   INITIAL_XRP drops exclusive.
+ */
+class NoZeroEscrow
+{
+    bool bad_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: a new account root must be the consequence of a payment,
+ *                   must have the right starting sequence, and the payment
+ *                   may not create more than one new account root.
+ */
+class ValidNewAccountRoot
+{
+    std::uint32_t accountsCreated_ = 0;
+    std::uint32_t accountSeq_ = 0;
+    bool pseudoAccount_ = false;
+    std::uint32_t flags_ = 0;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: Token holder's trustline balance cannot be negative after
+ * Clawback.
+ *
+ * We iterate all the trust lines affected by this transaction and ensure
+ * that no more than one trustline is modified, and also holder's balance is
+ * non-negative.
+ */
+class ValidClawback
+{
+    std::uint32_t trustlinesChanged = 0;
+    std::uint32_t mptokensChanged = 0;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariants: Pseudo-accounts have valid and consistent properties
+ *
+ * Pseudo-accounts have certain properties, and some of those properties are
+ * unique to pseudo-accounts. Check that all pseudo-accounts are following the
+ * rules, and that only pseudo-accounts look like pseudo-accounts.
+ *
+ */
+class ValidPseudoAccounts
+{
+    std::vector<std::string> errors_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariants: Some fields are unmodifiable
+ *
+ * Check that any fields specified as unmodifiable are not modified when the
+ * object is modified. Creation and deletion are ignored.
+ *
+ */
+class NoModifiedUnmodifiableFields
+{
+    // Pair is <before, after>.
+    std::set<std::pair<SLE::const_pointer, SLE::const_pointer>> changedEntries_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+// additional invariant checks can be declared above and then added to this
+// tuple
+using InvariantChecks = std::tuple<
+    TransactionFeeCheck,
+    AccountRootsNotDeleted,
+    AccountRootsDeletedClean,
+    LedgerEntryTypesMatch,
+    XRPBalanceChecks,
+    XRPNotCreated,
+    NoXRPTrustLines,
+    NoDeepFreezeTrustLinesWithoutFreeze,
+    TransfersNotFrozen,
+    NoBadOffers,
+    NoZeroEscrow,
+    ValidNewAccountRoot,
+    ValidNFTokenPage,
+    NFTokenCountTracking,
+    ValidClawback,
+    ValidMPTIssuance,
+    ValidPermissionedDomain,
+    ValidPermissionedDEX,
+    ValidAMM,
+    NoModifiedUnmodifiableFields,
+    ValidPseudoAccounts,
+    ValidLoanBroker,
+    ValidLoan,
+    ValidVault>;
+
+/**
+ * @brief get a tuple of all invariant checks
+ *
+ * @return std::tuple of instances that implement the required invariant check
+ * methods
+ *
+ * @see xrpl::InvariantChecker_PROTOTYPE
+ */
+inline InvariantChecks
+getInvariantChecks()
+{
+    return InvariantChecks{};
+}
+
+}  // namespace xrpl

include/xrpl/tx/invariants/InvariantCheckPrivilege.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <xrpl/protocol/STTx.h>
+
+#include <type_traits>
+
+namespace xrpl {
+
+/*
+assert(enforce)
+
+There are several asserts (or XRPL_ASSERTs) in invariant check files that check
+a variable named `enforce` when an invariant fails. At first glance, those
+asserts may look incorrect, but they are not.
+
+Those asserts take advantage of two facts:
+1. `asserts` are not (normally) executed in release builds.
+2. Invariants should *never* fail, except in tests that specifically modify
+   the open ledger to break them.
+
+This makes `assert(enforce)` sort of a second-layer of invariant enforcement
+aimed at _developers_. It's designed to fire if a developer writes code that
+violates an invariant, and runs it in unit tests or a develop build that _does
+not have the relevant amendments enabled_. It's intentionally a pain in the neck
+so that bad code gets caught and fixed as early as possible.
+*/
+
+enum Privilege {
+    noPriv = 0x0000,              // The transaction can not do any of the enumerated operations
+    createAcct = 0x0001,          // The transaction can create a new ACCOUNT_ROOT object.
+    createPseudoAcct = 0x0002,    // The transaction can create a pseudo account,
+                                  // which implies createAcct
+    mustDeleteAcct = 0x0004,      // The transaction must delete an ACCOUNT_ROOT object
+    mayDeleteAcct = 0x0008,       // The transaction may delete an ACCOUNT_ROOT
+                                  // object, but does not have to
+    overrideFreeze = 0x0010,      // The transaction can override some freeze rules
+    changeNFTCounts = 0x0020,     // The transaction can mint or burn an NFT
+    createMPTIssuance = 0x0040,   // The transaction can create a new MPT issuance
+    destroyMPTIssuance = 0x0080,  // The transaction can destroy an MPT issuance
+    mustAuthorizeMPT = 0x0100,    // The transaction MUST create or delete an MPT
+                                  // object (except by issuer)
+    mayAuthorizeMPT = 0x0200,     // The transaction MAY create or delete an MPT
+                                  // object (except by issuer)
+    mayDeleteMPT = 0x0400,        // The transaction MAY delete an MPT object. May not create.
+    mustModifyVault = 0x0800,     // The transaction must modify, delete or create, a vault
+    mayModifyVault = 0x1000,      // The transaction MAY modify, delete or create, a vault
+};
+
+constexpr Privilege
+operator|(Privilege lhs, Privilege rhs)
+{
+    return safe_cast<Privilege>(
+        safe_cast<std::underlying_type_t<Privilege>>(lhs) |
+        safe_cast<std::underlying_type_t<Privilege>>(rhs));
+}
+
+bool
+hasPrivilege(STTx const& tx, Privilege priv);
+
+}  // namespace xrpl

include/xrpl/tx/invariants/LoanInvariant.h

@@ -0,0 +1,75 @@
+#pragma once
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <map>
+#include <vector>
+
+namespace xrpl {
+
+/**
+ * @brief Invariants: Loan brokers are internally consistent
+ *
+ * 1. If `LoanBroker.OwnerCount = 0` the `DirectoryNode` will have at most one
+ *    node (the root), which will only hold entries for `RippleState` or
+ * `MPToken` objects.
+ *
+ */
+class ValidLoanBroker
+{
+    // Not all of these elements will necessarily be populated. Remaining items
+    // will be looked up as needed.
+    struct BrokerInfo
+    {
+        SLE::const_pointer brokerBefore = nullptr;
+        // After is used for most of the checks, except
+        // those that check changed values.
+        SLE::const_pointer brokerAfter = nullptr;
+    };
+    // Collect all the LoanBrokers found directly or indirectly through
+    // pseudo-accounts. Key is the brokerID / index. It will be used to find the
+    // LoanBroker object if brokerBefore and brokerAfter are nullptr
+    std::map<uint256, BrokerInfo> brokers_;
+    // Collect all the modified trust lines. Their high and low accounts will be
+    // loaded to look for LoanBroker pseudo-accounts.
+    std::vector<SLE::const_pointer> lines_;
+    // Collect all the modified MPTokens. Their accounts will be loaded to look
+    // for LoanBroker pseudo-accounts.
+    std::vector<SLE::const_pointer> mpts_;
+
+    bool
+    goodZeroDirectory(ReadView const& view, SLE::const_ref dir, beast::Journal const& j) const;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariants: Loans are internally consistent
+ *
+ * 1. If `Loan.PaymentRemaining = 0` then `Loan.PrincipalOutstanding = 0`
+ *
+ */
+class ValidLoan
+{
+    // Pair is <before, after>. After is used for most of the checks, except
+    // those that check changed values.
+    std::vector<std::pair<SLE::const_pointer, SLE::const_pointer>> loans_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/MPTInvariant.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <cstdint>
+
+namespace xrpl {
+
+class ValidMPTIssuance
+{
+    std::uint32_t mptIssuancesCreated_ = 0;
+    std::uint32_t mptIssuancesDeleted_ = 0;
+
+    std::uint32_t mptokensCreated_ = 0;
+    std::uint32_t mptokensDeleted_ = 0;
+    // non-MPT transactions may attempt to create
+    // MPToken by an issuer
+    bool mptCreatedByIssuer_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/NFTInvariant.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <cstdint>
+
+namespace xrpl {
+
+/**
+ * @brief Invariant: Validates several invariants for NFToken pages.
+ *
+ * The following checks are made:
+ *  - The page is correctly associated with the owner.
+ *  - The page is correctly ordered between the next and previous links.
+ *  - The page contains at least one and no more than 32 NFTokens.
+ *  - The NFTokens on this page do not belong on a lower or higher page.
+ *  - The NFTokens are correctly sorted on the page.
+ *  - Each URI, if present, is not empty.
+ */
+class ValidNFTokenPage
+{
+    bool badEntry_ = false;
+    bool badLink_ = false;
+    bool badSort_ = false;
+    bool badURI_ = false;
+    bool invalidSize_ = false;
+    bool deletedFinalPage_ = false;
+    bool deletedLink_ = false;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+/**
+ * @brief Invariant: Validates counts of NFTokens after all transaction types.
+ *
+ * The following checks are made:
+ *  - The number of minted or burned NFTokens can only be changed by
+ *    NFTokenMint or NFTokenBurn transactions.
+ *  - A successful NFTokenMint must increase the number of NFTokens.
+ *  - A failed NFTokenMint must not change the number of minted NFTokens.
+ *  - An NFTokenMint transaction cannot change the number of burned NFTokens.
+ *  - A successful NFTokenBurn must increase the number of burned NFTokens.
+ *  - A failed NFTokenBurn must not change the number of burned NFTokens.
+ *  - An NFTokenBurn transaction cannot change the number of minted NFTokens.
+ */
+class NFTokenCountTracking
+{
+    std::uint32_t beforeMintedTotal = 0;
+    std::uint32_t beforeBurnedTotal = 0;
+    std::uint32_t afterMintedTotal = 0;
+    std::uint32_t afterBurnedTotal = 0;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/PermissionedDEXInvariant.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+namespace xrpl {
+
+class ValidPermissionedDEX
+{
+    bool regularOffers_ = false;
+    bool badHybrids_ = false;
+    hash_set<uint256> domains_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/PermissionedDomainInvariant.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <vector>
+
+namespace xrpl {
+
+/**
+ * @brief Invariants: Permissioned Domains must have some rules and
+ * AcceptedCredentials must have length between 1 and 10 inclusive.
+ *
+ * Since only permissions constitute rules, an empty credentials list
+ * means that there are no rules and the invariant is violated.
+ *
+ * Credentials must be sorted and no duplicates allowed
+ *
+ */
+class ValidPermissionedDomain
+{
+    struct SleStatus
+    {
+        std::size_t credentialsSize_{0};
+        bool isSorted_ = false;
+        bool isUnique_ = false;
+        bool isDelete_ = false;
+    };
+    std::vector<SleStatus> sleStatus_;
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+}  // namespace xrpl

include/xrpl/tx/invariants/VaultInvariant.h

@@ -0,0 +1,77 @@
+#pragma once
+
+#include <xrpl/basics/Number.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TER.h>
+
+#include <unordered_map>
+#include <vector>
+
+namespace xrpl {
+
+/*
+ * @brief Invariants: Vault object and MPTokenIssuance for vault shares
+ *
+ * - vault deleted and vault created is empty
+ * - vault created must be linked to pseudo-account for shares and assets
+ * - vault must have MPTokenIssuance for shares
+ * - vault without shares outstanding must have no shares
+ * - loss unrealized does not exceed the difference between assets total and
+ *   assets available
+ * - assets available do not exceed assets total
+ * - vault deposit increases assets and share issuance, and adds to:
+ *   total assets, assets available, shares outstanding
+ * - vault withdrawal and clawback reduce assets and share issuance, and
+ *   subtracts from: total assets, assets available, shares outstanding
+ * - vault set must not alter the vault assets or shares balance
+ * - no vault transaction can change loss unrealized (it's updated by loan
+ *   transactions)
+ *
+ */
+class ValidVault
+{
+    Number static constexpr zero{};
+
+    struct Vault final
+    {
+        uint256 key = beast::zero;
+        Asset asset = {};
+        AccountID pseudoId = {};
+        AccountID owner = {};
+        uint192 shareMPTID = beast::zero;
+        Number assetsTotal = 0;
+        Number assetsAvailable = 0;
+        Number assetsMaximum = 0;
+        Number lossUnrealized = 0;
+
+        Vault static make(SLE const&);
+    };
+
+    struct Shares final
+    {
+        MPTIssue share = {};
+        std::uint64_t sharesTotal = 0;
+        std::uint64_t sharesMaximum = 0;
+
+        Shares static make(SLE const&);
+    };
+
+    std::vector<Vault> afterVault_ = {};
+    std::vector<Shares> afterMPTs_ = {};
+    std::vector<Vault> beforeVault_ = {};
+    std::vector<Shares> beforeMPTs_ = {};
+    std::unordered_map<uint256, Number> deltas_ = {};
+
+public:
+    void
+    visitEntry(bool, std::shared_ptr<SLE const> const&, std::shared_ptr<SLE const> const&);
+
+    bool
+    finalize(STTx const&, TER const, XRPAmount const, ReadView const&, beast::Journal const&);
+};
+
+}  // namespace xrpl

src/libxrpl/tx/ApplyContext.cpp

@@ -1,8 +1,9 @@
+#include <xrpl/tx/ApplyContext.h>
+//
 #include <xrpl/basics/Log.h>
 #include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/json/to_string.h>
-#include <xrpl/tx/ApplyContext.h>
-#include <xrpl/tx/InvariantCheck.h>
+#include <xrpl/tx/invariants/InvariantCheck.h>
 
 namespace xrpl {
 

src/libxrpl/tx/invariants/AMMInvariant.cpp

@@ -0,0 +1,305 @@
+#include <xrpl/tx/invariants/AMMInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/TxFormats.h>
+#include <xrpl/tx/transactors/AMM/AMMHelpers.h>
+#include <xrpl/tx/transactors/AMM/AMMUtils.h>
+
+namespace xrpl {
+
+void
+ValidAMM::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (isDelete)
+        return;
+
+    if (after)
+    {
+        auto const type = after->getType();
+        // AMM object changed
+        if (type == ltAMM)
+        {
+            ammAccount_ = after->getAccountID(sfAccount);
+            lptAMMBalanceAfter_ = after->getFieldAmount(sfLPTokenBalance);
+        }
+        // AMM pool changed
+        else if (
+            (type == ltRIPPLE_STATE && after->getFlags() & lsfAMMNode) ||
+            (type == ltACCOUNT_ROOT && after->isFieldPresent(sfAMMID)))
+        {
+            ammPoolChanged_ = true;
+        }
+    }
+
+    if (before)
+    {
+        // AMM object changed
+        if (before->getType() == ltAMM)
+        {
+            lptAMMBalanceBefore_ = before->getFieldAmount(sfLPTokenBalance);
+        }
+    }
+}
+
+static bool
+validBalances(
+    STAmount const& amount,
+    STAmount const& amount2,
+    STAmount const& lptAMMBalance,
+    ValidAMM::ZeroAllowed zeroAllowed)
+{
+    bool const positive =
+        amount > beast::zero && amount2 > beast::zero && lptAMMBalance > beast::zero;
+    if (zeroAllowed == ValidAMM::ZeroAllowed::Yes)
+        return positive ||
+            (amount == beast::zero && amount2 == beast::zero && lptAMMBalance == beast::zero);
+    return positive;
+}
+
+bool
+ValidAMM::finalizeVote(bool enforce, beast::Journal const& j) const
+{
+    if (lptAMMBalanceAfter_ != lptAMMBalanceBefore_ || ammPoolChanged_)
+    {
+        // LPTokens and the pool can not change on vote
+        // LCOV_EXCL_START
+        JLOG(j.error()) << "AMMVote invariant failed: " << lptAMMBalanceBefore_.value_or(STAmount{})
+                        << " " << lptAMMBalanceAfter_.value_or(STAmount{}) << " "
+                        << ammPoolChanged_;
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::finalizeBid(bool enforce, beast::Journal const& j) const
+{
+    if (ammPoolChanged_)
+    {
+        // The pool can not change on bid
+        // LCOV_EXCL_START
+        JLOG(j.error()) << "AMMBid invariant failed: pool changed";
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+    // LPTokens are burnt, therefore there should be fewer LPTokens
+    else if (
+        lptAMMBalanceBefore_ && lptAMMBalanceAfter_ &&
+        (*lptAMMBalanceAfter_ > *lptAMMBalanceBefore_ || *lptAMMBalanceAfter_ <= beast::zero))
+    {
+        // LCOV_EXCL_START
+        JLOG(j.error()) << "AMMBid invariant failed: " << *lptAMMBalanceBefore_ << " "
+                        << *lptAMMBalanceAfter_;
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::finalizeCreate(
+    STTx const& tx,
+    ReadView const& view,
+    bool enforce,
+    beast::Journal const& j) const
+{
+    if (!ammAccount_)
+    {
+        // LCOV_EXCL_START
+        JLOG(j.error()) << "AMMCreate invariant failed: AMM object is not created";
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+    else
+    {
+        auto const [amount, amount2] = ammPoolHolds(
+            view,
+            *ammAccount_,
+            tx[sfAmount].get<Issue>(),
+            tx[sfAmount2].get<Issue>(),
+            fhIGNORE_FREEZE,
+            j);
+        // Create invariant:
+        // sqrt(amount * amount2) == LPTokens
+        // all balances are greater than zero
+        if (!validBalances(amount, amount2, *lptAMMBalanceAfter_, ZeroAllowed::No) ||
+            ammLPTokens(amount, amount2, lptAMMBalanceAfter_->issue()) != *lptAMMBalanceAfter_)
+        {
+            JLOG(j.error()) << "AMMCreate invariant failed: " << amount << " " << amount2 << " "
+                            << *lptAMMBalanceAfter_;
+            if (enforce)
+                return false;
+        }
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::finalizeDelete(bool enforce, TER res, beast::Journal const& j) const
+{
+    if (ammAccount_)
+    {
+        // LCOV_EXCL_START
+        std::string const msg = (res == tesSUCCESS) ? "AMM object is not deleted on tesSUCCESS"
+                                                    : "AMM object is changed on tecINCOMPLETE";
+        JLOG(j.error()) << "AMMDelete invariant failed: " << msg;
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::finalizeDEX(bool enforce, beast::Journal const& j) const
+{
+    if (ammAccount_)
+    {
+        // LCOV_EXCL_START
+        JLOG(j.error()) << "AMM swap invariant failed: AMM object changed";
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::generalInvariant(
+    xrpl::STTx const& tx,
+    xrpl::ReadView const& view,
+    ZeroAllowed zeroAllowed,
+    beast::Journal const& j) const
+{
+    auto const [amount, amount2] = ammPoolHolds(
+        view,
+        *ammAccount_,
+        tx[sfAsset].get<Issue>(),
+        tx[sfAsset2].get<Issue>(),
+        fhIGNORE_FREEZE,
+        j);
+    // Deposit and Withdrawal invariant:
+    // sqrt(amount * amount2) >= LPTokens
+    // all balances are greater than zero
+    // unless on last withdrawal
+    auto const poolProductMean = root2(amount * amount2);
+    bool const nonNegativeBalances =
+        validBalances(amount, amount2, *lptAMMBalanceAfter_, zeroAllowed);
+    bool const strongInvariantCheck = poolProductMean >= *lptAMMBalanceAfter_;
+    // Allow for a small relative error if strongInvariantCheck fails
+    auto weakInvariantCheck = [&]() {
+        return *lptAMMBalanceAfter_ != beast::zero &&
+            withinRelativeDistance(poolProductMean, Number{*lptAMMBalanceAfter_}, Number{1, -11});
+    };
+    if (!nonNegativeBalances || (!strongInvariantCheck && !weakInvariantCheck()))
+    {
+        JLOG(j.error()) << "AMM " << tx.getTxnType()
+                        << " invariant failed: " << tx.getHash(HashPrefix::transactionID) << " "
+                        << ammPoolChanged_ << " " << amount << " " << amount2 << " "
+                        << poolProductMean << " " << lptAMMBalanceAfter_->getText() << " "
+                        << ((*lptAMMBalanceAfter_ == beast::zero)
+                                ? Number{1}
+                                : ((*lptAMMBalanceAfter_ - poolProductMean) / poolProductMean));
+        return false;
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::finalizeDeposit(
+    xrpl::STTx const& tx,
+    xrpl::ReadView const& view,
+    bool enforce,
+    beast::Journal const& j) const
+{
+    if (!ammAccount_)
+    {
+        // LCOV_EXCL_START
+        JLOG(j.error()) << "AMMDeposit invariant failed: AMM object is deleted";
+        if (enforce)
+            return false;
+        // LCOV_EXCL_STOP
+    }
+    else if (!generalInvariant(tx, view, ZeroAllowed::No, j) && enforce)
+        return false;
+
+    return true;
+}
+
+bool
+ValidAMM::finalizeWithdraw(
+    xrpl::STTx const& tx,
+    xrpl::ReadView const& view,
+    bool enforce,
+    beast::Journal const& j) const
+{
+    if (!ammAccount_)
+    {
+        // Last Withdraw or Clawback deleted AMM
+    }
+    else if (!generalInvariant(tx, view, ZeroAllowed::Yes, j))
+    {
+        if (enforce)
+            return false;
+    }
+
+    return true;
+}
+
+bool
+ValidAMM::finalize(
+    STTx const& tx,
+    TER const result,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    // Delete may return tecINCOMPLETE if there are too many
+    // trustlines to delete.
+    if (result != tesSUCCESS && result != tecINCOMPLETE)
+        return true;
+
+    bool const enforce = view.rules().enabled(fixAMMv1_3);
+
+    switch (tx.getTxnType())
+    {
+        case ttAMM_CREATE:
+            return finalizeCreate(tx, view, enforce, j);
+        case ttAMM_DEPOSIT:
+            return finalizeDeposit(tx, view, enforce, j);
+        case ttAMM_CLAWBACK:
+        case ttAMM_WITHDRAW:
+            return finalizeWithdraw(tx, view, enforce, j);
+        case ttAMM_BID:
+            return finalizeBid(enforce, j);
+        case ttAMM_VOTE:
+            return finalizeVote(enforce, j);
+        case ttAMM_DELETE:
+            return finalizeDelete(enforce, result, j);
+        case ttCHECK_CASH:
+        case ttOFFER_CREATE:
+        case ttPAYMENT:
+            return finalizeDEX(enforce, j);
+        default:
+            break;
+    }
+
+    return true;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/FreezeInvariant.cpp

@@ -0,0 +1,278 @@
+#include <xrpl/tx/invariants/FreezeInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/TxFormats.h>
+#include <xrpl/tx/invariants/InvariantCheckPrivilege.h>
+
+namespace xrpl {
+
+void
+TransfersNotFrozen::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    /*
+     * A trust line freeze state alone doesn't determine if a transfer is
+     * frozen. The transfer must be examined "end-to-end" because both sides of
+     * the transfer may have different freeze states and freeze impact depends
+     * on the transfer direction. This is why first we need to track the
+     * transfers using IssuerChanges senders/receivers.
+     *
+     * Only in validateIssuerChanges, after we collected all changes can we
+     * determine if the transfer is valid.
+     */
+    if (!isValidEntry(before, after))
+    {
+        return;
+    }
+
+    auto const balanceChange = calculateBalanceChange(before, after, isDelete);
+    if (balanceChange.signum() == 0)
+    {
+        return;
+    }
+
+    recordBalanceChanges(after, balanceChange);
+}
+
+bool
+TransfersNotFrozen::finalize(
+    STTx const& tx,
+    TER const ter,
+    XRPAmount const fee,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    /*
+     * We check this invariant regardless of deep freeze amendment status,
+     * allowing for detection and logging of potential issues even when the
+     * amendment is disabled.
+     *
+     * If an exploit that allows moving frozen assets is discovered,
+     * we can alert operators who monitor fatal messages and trigger assert in
+     * debug builds for an early warning.
+     *
+     * In an unlikely event that an exploit is found, this early detection
+     * enables encouraging the UNL to expedite deep freeze amendment activation
+     * or deploy hotfixes via new amendments. In case of a new amendment, we'd
+     * only have to change this line setting 'enforce' variable.
+     * enforce = view.rules().enabled(featureDeepFreeze) ||
+     *           view.rules().enabled(fixFreezeExploit);
+     */
+    [[maybe_unused]] bool const enforce = view.rules().enabled(featureDeepFreeze);
+
+    for (auto const& [issue, changes] : balanceChanges_)
+    {
+        auto const issuerSle = findIssuer(issue.account, view);
+        // It should be impossible for the issuer to not be found, but check
+        // just in case so rippled doesn't crash in release.
+        if (!issuerSle)
+        {
+            // The comment above starting with "assert(enforce)" explains this
+            // assert.
+            XRPL_ASSERT(
+                enforce,
+                "xrpl::TransfersNotFrozen::finalize : enforce "
+                "invariant.");
+            if (enforce)
+            {
+                return false;
+            }
+            continue;
+        }
+
+        if (!validateIssuerChanges(issuerSle, changes, tx, j, enforce))
+        {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool
+TransfersNotFrozen::isValidEntry(
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    // `after` can never be null, even if the trust line is deleted.
+    XRPL_ASSERT(after, "xrpl::TransfersNotFrozen::isValidEntry : valid after.");
+    if (!after)
+    {
+        return false;
+    }
+
+    if (after->getType() == ltACCOUNT_ROOT)
+    {
+        possibleIssuers_.emplace(after->at(sfAccount), after);
+        return false;
+    }
+
+    /* While LedgerEntryTypesMatch invariant also checks types, all invariants
+     * are processed regardless of previous failures.
+     *
+     * This type check is still necessary here because it prevents potential
+     * issues in subsequent processing.
+     */
+    return after->getType() == ltRIPPLE_STATE && (!before || before->getType() == ltRIPPLE_STATE);
+}
+
+STAmount
+TransfersNotFrozen::calculateBalanceChange(
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after,
+    bool isDelete)
+{
+    auto const getBalance = [](auto const& line, auto const& other, bool zero) {
+        STAmount amt = line ? line->at(sfBalance) : other->at(sfBalance).zeroed();
+        return zero ? amt.zeroed() : amt;
+    };
+
+    /* Trust lines can be created dynamically by other transactions such as
+     * Payment and OfferCreate that cross offers. Such trust line won't be
+     * created frozen, but the sender might be, so the starting balance must be
+     * treated as zero.
+     */
+    auto const balanceBefore = getBalance(before, after, false);
+
+    /* Same as above, trust lines can be dynamically deleted, and for frozen
+     * trust lines, payments not involving the issuer must be blocked. This is
+     * achieved by treating the final balance as zero when isDelete=true to
+     * ensure frozen line restrictions are enforced even during deletion.
+     */
+    auto const balanceAfter = getBalance(after, before, isDelete);
+
+    return balanceAfter - balanceBefore;
+}
+
+void
+TransfersNotFrozen::recordBalance(Issue const& issue, BalanceChange change)
+{
+    XRPL_ASSERT(
+        change.balanceChangeSign,
+        "xrpl::TransfersNotFrozen::recordBalance : valid trustline "
+        "balance sign.");
+    auto& changes = balanceChanges_[issue];
+    if (change.balanceChangeSign < 0)
+        changes.senders.emplace_back(std::move(change));
+    else
+        changes.receivers.emplace_back(std::move(change));
+}
+
+void
+TransfersNotFrozen::recordBalanceChanges(
+    std::shared_ptr<SLE const> const& after,
+    STAmount const& balanceChange)
+{
+    auto const balanceChangeSign = balanceChange.signum();
+    auto const currency = after->at(sfBalance).getCurrency();
+
+    // Change from low account's perspective, which is trust line default
+    recordBalance({currency, after->at(sfHighLimit).getIssuer()}, {after, balanceChangeSign});
+
+    // Change from high account's perspective, which reverses the sign.
+    recordBalance({currency, after->at(sfLowLimit).getIssuer()}, {after, -balanceChangeSign});
+}
+
+std::shared_ptr<SLE const>
+TransfersNotFrozen::findIssuer(AccountID const& issuerID, ReadView const& view)
+{
+    if (auto it = possibleIssuers_.find(issuerID); it != possibleIssuers_.end())
+    {
+        return it->second;
+    }
+
+    return view.read(keylet::account(issuerID));
+}
+
+bool
+TransfersNotFrozen::validateIssuerChanges(
+    std::shared_ptr<SLE const> const& issuer,
+    IssuerChanges const& changes,
+    STTx const& tx,
+    beast::Journal const& j,
+    bool enforce)
+{
+    if (!issuer)
+    {
+        return false;
+    }
+
+    bool const globalFreeze = issuer->isFlag(lsfGlobalFreeze);
+    if (changes.receivers.empty() || changes.senders.empty())
+    {
+        /* If there are no receivers, then the holder(s) are returning
+         * their tokens to the issuer. Likewise, if there are no
+         * senders, then the issuer is issuing tokens to the holder(s).
+         * This is allowed regardless of the issuer's freeze flags. (The
+         * holder may have contradicting freeze flags, but that will be
+         * checked when the holder is treated as issuer.)
+         */
+        return true;
+    }
+
+    for (auto const& actors : {changes.senders, changes.receivers})
+    {
+        for (auto const& change : actors)
+        {
+            bool const high = change.line->at(sfLowLimit).getIssuer() == issuer->at(sfAccount);
+
+            if (!validateFrozenState(change, high, tx, j, enforce, globalFreeze))
+            {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+bool
+TransfersNotFrozen::validateFrozenState(
+    BalanceChange const& change,
+    bool high,
+    STTx const& tx,
+    beast::Journal const& j,
+    bool enforce,
+    bool globalFreeze)
+{
+    bool const freeze =
+        change.balanceChangeSign < 0 && change.line->isFlag(high ? lsfLowFreeze : lsfHighFreeze);
+    bool const deepFreeze = change.line->isFlag(high ? lsfLowDeepFreeze : lsfHighDeepFreeze);
+    bool const frozen = globalFreeze || deepFreeze || freeze;
+
+    bool const isAMMLine = change.line->isFlag(lsfAMMNode);
+
+    if (!frozen)
+    {
+        return true;
+    }
+
+    // AMMClawbacks are allowed to override some freeze rules
+    if ((!isAMMLine || globalFreeze) && hasPrivilege(tx, overrideFreeze))
+    {
+        JLOG(j.debug()) << "Invariant check allowing funds to be moved "
+                        << (change.balanceChangeSign > 0 ? "to" : "from")
+                        << " a frozen trustline for AMMClawback " << tx.getTransactionID();
+        return true;
+    }
+
+    JLOG(j.fatal()) << "Invariant failed: Attempting to move frozen funds for "
+                    << tx.getTransactionID();
+    // The comment above starting with "assert(enforce)" explains this assert.
+    XRPL_ASSERT(
+        enforce,
+        "xrpl::TransfersNotFrozen::validateFrozenState : enforce "
+        "invariant.");
+
+    if (enforce)
+    {
+        return false;
+    }
+
+    return true;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/LoanInvariant.cpp

@@ -0,0 +1,278 @@
+#include <xrpl/tx/invariants/LoanInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/ledger/View.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/STNumber.h>
+#include <xrpl/protocol/TxFormats.h>
+
+namespace xrpl {
+
+void
+ValidLoanBroker::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (after)
+    {
+        if (after->getType() == ltLOAN_BROKER)
+        {
+            auto& broker = brokers_[after->key()];
+            broker.brokerBefore = before;
+            broker.brokerAfter = after;
+        }
+        else if (after->getType() == ltACCOUNT_ROOT && after->isFieldPresent(sfLoanBrokerID))
+        {
+            auto const& loanBrokerID = after->at(sfLoanBrokerID);
+            // create an entry if one doesn't already exist
+            brokers_.emplace(loanBrokerID, BrokerInfo{});
+        }
+        else if (after->getType() == ltRIPPLE_STATE)
+        {
+            lines_.emplace_back(after);
+        }
+        else if (after->getType() == ltMPTOKEN)
+        {
+            mpts_.emplace_back(after);
+        }
+    }
+}
+
+bool
+ValidLoanBroker::goodZeroDirectory(
+    ReadView const& view,
+    SLE::const_ref dir,
+    beast::Journal const& j) const
+{
+    auto const next = dir->at(~sfIndexNext);
+    auto const prev = dir->at(~sfIndexPrevious);
+    if ((prev && *prev) || (next && *next))
+    {
+        JLOG(j.fatal()) << "Invariant failed: Loan Broker with zero "
+                           "OwnerCount has multiple directory pages";
+        return false;
+    }
+    auto indexes = dir->getFieldV256(sfIndexes);
+    if (indexes.size() > 1)
+    {
+        JLOG(j.fatal()) << "Invariant failed: Loan Broker with zero "
+                           "OwnerCount has multiple indexes in the Directory root";
+        return false;
+    }
+    if (indexes.size() == 1)
+    {
+        auto const index = indexes.value().front();
+        auto const sle = view.read(keylet::unchecked(index));
+        if (!sle)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker directory corrupt";
+            return false;
+        }
+        if (sle->getType() != ltRIPPLE_STATE && sle->getType() != ltMPTOKEN)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker with zero "
+                               "OwnerCount has an unexpected entry in the directory";
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool
+ValidLoanBroker::finalize(
+    STTx const& tx,
+    TER const,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    // Loan Brokers will not exist on ledger if the Lending Protocol amendment
+    // is not enabled, so there's no need to check it.
+
+    for (auto const& line : lines_)
+    {
+        for (auto const& field : {&sfLowLimit, &sfHighLimit})
+        {
+            auto const account = view.read(keylet::account(line->at(*field).getIssuer()));
+            // This Invariant doesn't know about the rules for Trust Lines, so
+            // if the account is missing, don't treat it as an error. This
+            // loop is only concerned with finding Broker pseudo-accounts
+            if (account && account->isFieldPresent(sfLoanBrokerID))
+            {
+                auto const& loanBrokerID = account->at(sfLoanBrokerID);
+                // create an entry if one doesn't already exist
+                brokers_.emplace(loanBrokerID, BrokerInfo{});
+            }
+        }
+    }
+    for (auto const& mpt : mpts_)
+    {
+        auto const account = view.read(keylet::account(mpt->at(sfAccount)));
+        // This Invariant doesn't know about the rules for MPTokens, so
+        // if the account is missing, don't treat is as an error. This
+        // loop is only concerned with finding Broker pseudo-accounts
+        if (account && account->isFieldPresent(sfLoanBrokerID))
+        {
+            auto const& loanBrokerID = account->at(sfLoanBrokerID);
+            // create an entry if one doesn't already exist
+            brokers_.emplace(loanBrokerID, BrokerInfo{});
+        }
+    }
+
+    for (auto const& [brokerID, broker] : brokers_)
+    {
+        auto const& after =
+            broker.brokerAfter ? broker.brokerAfter : view.read(keylet::loanbroker(brokerID));
+
+        if (!after)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker missing";
+            return false;
+        }
+
+        auto const& before = broker.brokerBefore;
+
+        // https://github.com/Tapanito/XRPL-Standards/blob/xls-66-lending-protocol/XLS-0066d-lending-protocol/README.md#3123-invariants
+        // If `LoanBroker.OwnerCount = 0` the `DirectoryNode` will have at most
+        // one node (the root), which will only hold entries for `RippleState`
+        // or `MPToken` objects.
+        if (after->at(sfOwnerCount) == 0)
+        {
+            auto const dir = view.read(keylet::ownerDir(after->at(sfAccount)));
+            if (dir)
+            {
+                if (!goodZeroDirectory(view, dir, j))
+                {
+                    return false;
+                }
+            }
+        }
+        if (before && before->at(sfLoanSequence) > after->at(sfLoanSequence))
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker sequence number "
+                               "decreased";
+            return false;
+        }
+        if (after->at(sfDebtTotal) < 0)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker debt total is negative";
+            return false;
+        }
+        if (after->at(sfCoverAvailable) < 0)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker cover available is negative";
+            return false;
+        }
+        auto const vault = view.read(keylet::vault(after->at(sfVaultID)));
+        if (!vault)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker vault ID is invalid";
+            return false;
+        }
+        auto const& vaultAsset = vault->at(sfAsset);
+        if (after->at(sfCoverAvailable) < accountHolds(
+                                              view,
+                                              after->at(sfAccount),
+                                              vaultAsset,
+                                              FreezeHandling::fhIGNORE_FREEZE,
+                                              AuthHandling::ahIGNORE_AUTH,
+                                              j))
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Broker cover available "
+                               "is less than pseudo-account asset balance";
+            return false;
+        }
+    }
+    return true;
+}
+
+//------------------------------------------------------------------------------
+
+void
+ValidLoan::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (after && after->getType() == ltLOAN)
+    {
+        loans_.emplace_back(before, after);
+    }
+}
+
+bool
+ValidLoan::finalize(
+    STTx const& tx,
+    TER const,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    // Loans will not exist on ledger if the Lending Protocol amendment
+    // is not enabled, so there's no need to check it.
+
+    for (auto const& [before, after] : loans_)
+    {
+        // https://github.com/Tapanito/XRPL-Standards/blob/xls-66-lending-protocol/XLS-0066d-lending-protocol/README.md#3223-invariants
+        // If `Loan.PaymentRemaining = 0` then the loan MUST be fully paid off
+        if (after->at(sfPaymentRemaining) == 0 &&
+            (after->at(sfTotalValueOutstanding) != beast::zero ||
+             after->at(sfPrincipalOutstanding) != beast::zero ||
+             after->at(sfManagementFeeOutstanding) != beast::zero))
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan with zero payments "
+                               "remaining has not been paid off";
+            return false;
+        }
+        // If `Loan.PaymentRemaining != 0` then the loan MUST NOT be fully paid
+        // off
+        if (after->at(sfPaymentRemaining) != 0 &&
+            after->at(sfTotalValueOutstanding) == beast::zero &&
+            after->at(sfPrincipalOutstanding) == beast::zero &&
+            after->at(sfManagementFeeOutstanding) == beast::zero)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan with zero payments "
+                               "remaining has not been paid off";
+            return false;
+        }
+        if (before && (before->isFlag(lsfLoanOverpayment) != after->isFlag(lsfLoanOverpayment)))
+        {
+            JLOG(j.fatal()) << "Invariant failed: Loan Overpayment flag changed";
+            return false;
+        }
+        // Must not be negative - STNumber
+        for (auto const field :
+             {&sfLoanServiceFee,
+              &sfLatePaymentFee,
+              &sfClosePaymentFee,
+              &sfPrincipalOutstanding,
+              &sfTotalValueOutstanding,
+              &sfManagementFeeOutstanding})
+        {
+            if (after->at(*field) < 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: " << field->getName() << " is negative ";
+                return false;
+            }
+        }
+        // Must be positive - STNumber
+        for (auto const field : {
+                 &sfPeriodicPayment,
+             })
+        {
+            if (after->at(*field) <= 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: " << field->getName()
+                                << " is zero or negative ";
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/MPTInvariant.cpp

@@ -0,0 +1,192 @@
+#include <xrpl/tx/invariants/MPTInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/TxFormats.h>
+#include <xrpl/tx/invariants/InvariantCheckPrivilege.h>
+
+namespace xrpl {
+
+void
+ValidMPTIssuance::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (after && after->getType() == ltMPTOKEN_ISSUANCE)
+    {
+        if (isDelete)
+            mptIssuancesDeleted_++;
+        else if (!before)
+            mptIssuancesCreated_++;
+    }
+
+    if (after && after->getType() == ltMPTOKEN)
+    {
+        if (isDelete)
+            mptokensDeleted_++;
+        else if (!before)
+        {
+            mptokensCreated_++;
+            MPTIssue const mptIssue{after->at(sfMPTokenIssuanceID)};
+            if (mptIssue.getIssuer() == after->at(sfAccount))
+                mptCreatedByIssuer_ = true;
+        }
+    }
+}
+
+bool
+ValidMPTIssuance::finalize(
+    STTx const& tx,
+    TER const result,
+    XRPAmount const _fee,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    if (result == tesSUCCESS)
+    {
+        auto const& rules = view.rules();
+        [[maybe_unused]]
+        bool enforceCreatedByIssuer =
+            rules.enabled(featureSingleAssetVault) || rules.enabled(featureLendingProtocol);
+        if (mptCreatedByIssuer_)
+        {
+            JLOG(j.fatal()) << "Invariant failed: MPToken created for the MPT issuer";
+            // The comment above starting with "assert(enforce)" explains this
+            // assert.
+            XRPL_ASSERT_PARTS(
+                enforceCreatedByIssuer, "xrpl::ValidMPTIssuance::finalize", "no issuer MPToken");
+            if (enforceCreatedByIssuer)
+                return false;
+        }
+
+        auto const txnType = tx.getTxnType();
+        if (hasPrivilege(tx, createMPTIssuance))
+        {
+            if (mptIssuancesCreated_ == 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: transaction "
+                                   "succeeded without creating a MPT issuance";
+            }
+            else if (mptIssuancesDeleted_ != 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: transaction "
+                                   "succeeded while removing MPT issuances";
+            }
+            else if (mptIssuancesCreated_ > 1)
+            {
+                JLOG(j.fatal()) << "Invariant failed: transaction "
+                                   "succeeded but created multiple issuances";
+            }
+
+            return mptIssuancesCreated_ == 1 && mptIssuancesDeleted_ == 0;
+        }
+
+        if (hasPrivilege(tx, destroyMPTIssuance))
+        {
+            if (mptIssuancesDeleted_ == 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT issuance deletion "
+                                   "succeeded without removing a MPT issuance";
+            }
+            else if (mptIssuancesCreated_ > 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT issuance deletion "
+                                   "succeeded while creating MPT issuances";
+            }
+            else if (mptIssuancesDeleted_ > 1)
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT issuance deletion "
+                                   "succeeded but deleted multiple issuances";
+            }
+
+            return mptIssuancesCreated_ == 0 && mptIssuancesDeleted_ == 1;
+        }
+
+        bool const lendingProtocolEnabled = view.rules().enabled(featureLendingProtocol);
+        // ttESCROW_FINISH may authorize an MPT, but it can't have the
+        // mayAuthorizeMPT privilege, because that may cause
+        // non-amendment-gated side effects.
+        bool const enforceEscrowFinish = (txnType == ttESCROW_FINISH) &&
+            (view.rules().enabled(featureSingleAssetVault) || lendingProtocolEnabled);
+        if (hasPrivilege(tx, mustAuthorizeMPT | mayAuthorizeMPT) || enforceEscrowFinish)
+        {
+            bool const submittedByIssuer = tx.isFieldPresent(sfHolder);
+
+            if (mptIssuancesCreated_ > 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT authorize "
+                                   "succeeded but created MPT issuances";
+                return false;
+            }
+            else if (mptIssuancesDeleted_ > 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT authorize "
+                                   "succeeded but deleted issuances";
+                return false;
+            }
+            else if (lendingProtocolEnabled && mptokensCreated_ + mptokensDeleted_ > 1)
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT authorize succeeded "
+                                   "but created/deleted bad number mptokens";
+                return false;
+            }
+            else if (submittedByIssuer && (mptokensCreated_ > 0 || mptokensDeleted_ > 0))
+            {
+                JLOG(j.fatal()) << "Invariant failed: MPT authorize submitted by issuer "
+                                   "succeeded but created/deleted mptokens";
+                return false;
+            }
+            else if (
+                !submittedByIssuer && hasPrivilege(tx, mustAuthorizeMPT) &&
+                (mptokensCreated_ + mptokensDeleted_ != 1))
+            {
+                // if the holder submitted this tx, then a mptoken must be
+                // either created or deleted.
+                JLOG(j.fatal()) << "Invariant failed: MPT authorize submitted by holder "
+                                   "succeeded but created/deleted bad number of mptokens";
+                return false;
+            }
+
+            return true;
+        }
+        if (txnType == ttESCROW_FINISH)
+        {
+            // ttESCROW_FINISH may authorize an MPT, but it can't have the
+            // mayAuthorizeMPT privilege, because that may cause
+            // non-amendment-gated side effects.
+            XRPL_ASSERT_PARTS(
+                !enforceEscrowFinish, "xrpl::ValidMPTIssuance::finalize", "not escrow finish tx");
+            return true;
+        }
+
+        if (hasPrivilege(tx, mayDeleteMPT) && mptokensDeleted_ == 1 && mptokensCreated_ == 0 &&
+            mptIssuancesCreated_ == 0 && mptIssuancesDeleted_ == 0)
+            return true;
+    }
+
+    if (mptIssuancesCreated_ != 0)
+    {
+        JLOG(j.fatal()) << "Invariant failed: a MPT issuance was created";
+    }
+    else if (mptIssuancesDeleted_ != 0)
+    {
+        JLOG(j.fatal()) << "Invariant failed: a MPT issuance was deleted";
+    }
+    else if (mptokensCreated_ != 0)
+    {
+        JLOG(j.fatal()) << "Invariant failed: a MPToken was created";
+    }
+    else if (mptokensDeleted_ != 0)
+    {
+        JLOG(j.fatal()) << "Invariant failed: a MPToken was deleted";
+    }
+
+    return mptIssuancesCreated_ == 0 && mptIssuancesDeleted_ == 0 && mptokensCreated_ == 0 &&
+        mptokensDeleted_ == 0;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/NFTInvariant.cpp

@@ -0,0 +1,274 @@
+#include <xrpl/tx/invariants/NFTInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/TxFormats.h>
+#include <xrpl/protocol/nftPageMask.h>
+#include <xrpl/tx/invariants/InvariantCheckPrivilege.h>
+#include <xrpl/tx/transactors/NFT/NFTokenUtils.h>
+
+namespace xrpl {
+
+void
+ValidNFTokenPage::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    static constexpr uint256 const& pageBits = nft::pageMask;
+    static constexpr uint256 const accountBits = ~pageBits;
+
+    if ((before && before->getType() != ltNFTOKEN_PAGE) ||
+        (after && after->getType() != ltNFTOKEN_PAGE))
+        return;
+
+    auto check = [this, isDelete](std::shared_ptr<SLE const> const& sle) {
+        uint256 const account = sle->key() & accountBits;
+        uint256 const hiLimit = sle->key() & pageBits;
+        std::optional<uint256> const prev = (*sle)[~sfPreviousPageMin];
+
+        // Make sure that any page links...
+        //  1. Are properly associated with the owning account and
+        //  2. The page is correctly ordered between links.
+        if (prev)
+        {
+            if (account != (*prev & accountBits))
+                badLink_ = true;
+
+            if (hiLimit <= (*prev & pageBits))
+                badLink_ = true;
+        }
+
+        if (auto const next = (*sle)[~sfNextPageMin])
+        {
+            if (account != (*next & accountBits))
+                badLink_ = true;
+
+            if (hiLimit >= (*next & pageBits))
+                badLink_ = true;
+        }
+
+        {
+            auto const& nftokens = sle->getFieldArray(sfNFTokens);
+
+            // An NFTokenPage should never contain too many tokens or be empty.
+            if (std::size_t const nftokenCount = nftokens.size();
+                (!isDelete && nftokenCount == 0) || nftokenCount > dirMaxTokensPerPage)
+                invalidSize_ = true;
+
+            // If prev is valid, use it to establish a lower bound for
+            // page entries.  If prev is not valid the lower bound is zero.
+            uint256 const loLimit = prev ? *prev & pageBits : uint256(beast::zero);
+
+            // Also verify that all NFTokenIDs in the page are sorted.
+            uint256 loCmp = loLimit;
+            for (auto const& obj : nftokens)
+            {
+                uint256 const tokenID = obj[sfNFTokenID];
+                if (!nft::compareTokens(loCmp, tokenID))
+                    badSort_ = true;
+                loCmp = tokenID;
+
+                // None of the NFTs on this page should belong on lower or
+                // higher pages.
+                if (uint256 const tokenPageBits = tokenID & pageBits;
+                    tokenPageBits < loLimit || tokenPageBits >= hiLimit)
+                    badEntry_ = true;
+
+                if (auto uri = obj[~sfURI]; uri && uri->empty())
+                    badURI_ = true;
+            }
+        }
+    };
+
+    if (before)
+    {
+        check(before);
+
+        // While an account's NFToken directory contains any NFTokens, the last
+        // NFTokenPage (with 96 bits of 1 in the low part of the index) should
+        // never be deleted.
+        if (isDelete && (before->key() & nft::pageMask) == nft::pageMask &&
+            before->isFieldPresent(sfPreviousPageMin))
+        {
+            deletedFinalPage_ = true;
+        }
+    }
+
+    if (after)
+        check(after);
+
+    if (!isDelete && before && after)
+    {
+        // If the NFTokenPage
+        //  1. Has a NextMinPage field in before, but loses it in after, and
+        //  2. This is not the last page in the directory
+        // Then we have identified a corruption in the links between the
+        // NFToken pages in the NFToken directory.
+        if ((before->key() & nft::pageMask) != nft::pageMask &&
+            before->isFieldPresent(sfNextPageMin) && !after->isFieldPresent(sfNextPageMin))
+        {
+            deletedLink_ = true;
+        }
+    }
+}
+
+bool
+ValidNFTokenPage::finalize(
+    STTx const& tx,
+    TER const result,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    if (badLink_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: NFT page is improperly linked.";
+        return false;
+    }
+
+    if (badEntry_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: NFT found in incorrect page.";
+        return false;
+    }
+
+    if (badSort_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: NFTs on page are not sorted.";
+        return false;
+    }
+
+    if (badURI_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: NFT contains empty URI.";
+        return false;
+    }
+
+    if (invalidSize_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: NFT page has invalid size.";
+        return false;
+    }
+
+    if (view.rules().enabled(fixNFTokenPageLinks))
+    {
+        if (deletedFinalPage_)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Last NFT page deleted with "
+                               "non-empty directory.";
+            return false;
+        }
+        if (deletedLink_)
+        {
+            JLOG(j.fatal()) << "Invariant failed: Lost NextMinPage link.";
+            return false;
+        }
+    }
+
+    return true;
+}
+
+//------------------------------------------------------------------------------
+void
+NFTokenCountTracking::visitEntry(
+    bool,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (before && before->getType() == ltACCOUNT_ROOT)
+    {
+        beforeMintedTotal += (*before)[~sfMintedNFTokens].value_or(0);
+        beforeBurnedTotal += (*before)[~sfBurnedNFTokens].value_or(0);
+    }
+
+    if (after && after->getType() == ltACCOUNT_ROOT)
+    {
+        afterMintedTotal += (*after)[~sfMintedNFTokens].value_or(0);
+        afterBurnedTotal += (*after)[~sfBurnedNFTokens].value_or(0);
+    }
+}
+
+bool
+NFTokenCountTracking::finalize(
+    STTx const& tx,
+    TER const result,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    if (!hasPrivilege(tx, changeNFTCounts))
+    {
+        if (beforeMintedTotal != afterMintedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: the number of minted tokens "
+                               "changed without a mint transaction!";
+            return false;
+        }
+
+        if (beforeBurnedTotal != afterBurnedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: the number of burned tokens "
+                               "changed without a burn transaction!";
+            return false;
+        }
+
+        return true;
+    }
+
+    if (tx.getTxnType() == ttNFTOKEN_MINT)
+    {
+        if (result == tesSUCCESS && beforeMintedTotal >= afterMintedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: successful minting didn't increase "
+                               "the number of minted tokens.";
+            return false;
+        }
+
+        if (result != tesSUCCESS && beforeMintedTotal != afterMintedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: failed minting changed the "
+                               "number of minted tokens.";
+            return false;
+        }
+
+        if (beforeBurnedTotal != afterBurnedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: minting changed the number of "
+                               "burned tokens.";
+            return false;
+        }
+    }
+
+    if (tx.getTxnType() == ttNFTOKEN_BURN)
+    {
+        if (result == tesSUCCESS)
+        {
+            if (beforeBurnedTotal >= afterBurnedTotal)
+            {
+                JLOG(j.fatal()) << "Invariant failed: successful burning didn't increase "
+                                   "the number of burned tokens.";
+                return false;
+            }
+        }
+
+        if (result != tesSUCCESS && beforeBurnedTotal != afterBurnedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: failed burning changed the "
+                               "number of burned tokens.";
+            return false;
+        }
+
+        if (beforeMintedTotal != afterMintedTotal)
+        {
+            JLOG(j.fatal()) << "Invariant failed: burning changed the number of "
+                               "minted tokens.";
+            return false;
+        }
+    }
+
+    return true;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/PermissionedDEXInvariant.cpp

@@ -0,0 +1,93 @@
+#include <xrpl/tx/invariants/PermissionedDEXInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/STArray.h>
+#include <xrpl/protocol/TxFormats.h>
+
+namespace xrpl {
+
+void
+ValidPermissionedDEX::visitEntry(
+    bool,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (after && after->getType() == ltDIR_NODE)
+    {
+        if (after->isFieldPresent(sfDomainID))
+            domains_.insert(after->getFieldH256(sfDomainID));
+    }
+
+    if (after && after->getType() == ltOFFER)
+    {
+        if (after->isFieldPresent(sfDomainID))
+            domains_.insert(after->getFieldH256(sfDomainID));
+        else
+            regularOffers_ = true;
+
+        // if a hybrid offer is missing domain or additional book, there's
+        // something wrong
+        if (after->isFlag(lsfHybrid) &&
+            (!after->isFieldPresent(sfDomainID) || !after->isFieldPresent(sfAdditionalBooks) ||
+             after->getFieldArray(sfAdditionalBooks).size() > 1))
+            badHybrids_ = true;
+    }
+}
+
+bool
+ValidPermissionedDEX::finalize(
+    STTx const& tx,
+    TER const result,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    auto const txType = tx.getTxnType();
+    if ((txType != ttPAYMENT && txType != ttOFFER_CREATE) || result != tesSUCCESS)
+        return true;
+
+    // For each offercreate transaction, check if
+    // permissioned offers are valid
+    if (txType == ttOFFER_CREATE && badHybrids_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: hybrid offer is malformed";
+        return false;
+    }
+
+    if (!tx.isFieldPresent(sfDomainID))
+        return true;
+
+    auto const domain = tx.getFieldH256(sfDomainID);
+
+    if (!view.exists(keylet::permissionedDomain(domain)))
+    {
+        JLOG(j.fatal()) << "Invariant failed: domain doesn't exist";
+        return false;
+    }
+
+    // for both payment and offercreate, there shouldn't be another domain
+    // that's different from the domain specified
+    for (auto const& d : domains_)
+    {
+        if (d != domain)
+        {
+            JLOG(j.fatal()) << "Invariant failed: transaction"
+                               " consumed wrong domains";
+            return false;
+        }
+    }
+
+    if (regularOffers_)
+    {
+        JLOG(j.fatal()) << "Invariant failed: domain transaction"
+                           " affected regular offers";
+        return false;
+    }
+
+    return true;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/PermissionedDomainInvariant.cpp

@@ -0,0 +1,162 @@
+#include <xrpl/tx/invariants/PermissionedDomainInvariant.h>
+//
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/ledger/CredentialHelpers.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/STArray.h>
+#include <xrpl/protocol/TxFormats.h>
+
+namespace xrpl {
+
+void
+ValidPermissionedDomain::visitEntry(
+    bool isDel,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    if (before && before->getType() != ltPERMISSIONED_DOMAIN)
+        return;
+    if (after && after->getType() != ltPERMISSIONED_DOMAIN)
+        return;
+
+    auto check = [isDel](std::vector<SleStatus>& sleStatus, std::shared_ptr<SLE const> const& sle) {
+        auto const& credentials = sle->getFieldArray(sfAcceptedCredentials);
+        auto const sorted = credentials::makeSorted(credentials);
+
+        SleStatus ss{credentials.size(), false, !sorted.empty(), isDel};
+
+        // If array have duplicates then all the other checks are invalid
+        if (ss.isUnique_)
+        {
+            unsigned i = 0;
+            for (auto const& cred : sorted)
+            {
+                auto const& credTx = credentials[i++];
+                ss.isSorted_ =
+                    (cred.first == credTx[sfIssuer]) && (cred.second == credTx[sfCredentialType]);
+                if (!ss.isSorted_)
+                    break;
+            }
+        }
+        sleStatus.emplace_back(std::move(ss));
+    };
+
+    if (after)
+        check(sleStatus_, after);
+}
+
+bool
+ValidPermissionedDomain::finalize(
+    STTx const& tx,
+    TER const result,
+    XRPAmount const,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    auto check = [](SleStatus const& sleStatus, beast::Journal const& j) {
+        if (!sleStatus.credentialsSize_)
+        {
+            JLOG(j.fatal()) << "Invariant failed: permissioned domain with "
+                               "no rules.";
+            return false;
+        }
+
+        if (sleStatus.credentialsSize_ > maxPermissionedDomainCredentialsArraySize)
+        {
+            JLOG(j.fatal()) << "Invariant failed: permissioned domain bad "
+                               "credentials size "
+                            << sleStatus.credentialsSize_;
+            return false;
+        }
+
+        if (!sleStatus.isUnique_)
+        {
+            JLOG(j.fatal()) << "Invariant failed: permissioned domain credentials "
+                               "aren't unique";
+            return false;
+        }
+
+        if (!sleStatus.isSorted_)
+        {
+            JLOG(j.fatal()) << "Invariant failed: permissioned domain credentials "
+                               "aren't sorted";
+            return false;
+        }
+
+        return true;
+    };
+
+    if (view.rules().enabled(fixPermissionedDomainInvariant))
+    {
+        // No permissioned domains should be affected if the transaction failed
+        if (result != tesSUCCESS)
+            // If nothing changed, all is good. If there were changes, that's
+            // bad.
+            return sleStatus_.empty();
+
+        if (sleStatus_.size() > 1)
+        {
+            JLOG(j.fatal()) << "Invariant failed: transaction affected more "
+                               "than 1 permissioned domain entry.";
+            return false;
+        }
+
+        switch (tx.getTxnType())
+        {
+            case ttPERMISSIONED_DOMAIN_SET: {
+                if (sleStatus_.empty())
+                {
+                    JLOG(j.fatal()) << "Invariant failed: no domain objects affected by "
+                                       "PermissionedDomainSet";
+                    return false;
+                }
+
+                auto const& sleStatus = sleStatus_[0];
+                if (sleStatus.isDelete_)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: domain object "
+                                       "deleted by PermissionedDomainSet";
+                    return false;
+                }
+                return check(sleStatus, j);
+            }
+            case ttPERMISSIONED_DOMAIN_DELETE: {
+                if (sleStatus_.empty())
+                {
+                    JLOG(j.fatal()) << "Invariant failed: no domain objects affected by "
+                                       "PermissionedDomainDelete";
+                    return false;
+                }
+
+                if (!sleStatus_[0].isDelete_)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: domain object "
+                                       "modified, but not deleted by "
+                                       "PermissionedDomainDelete";
+                    return false;
+                }
+                return true;
+            }
+            default: {
+                if (!sleStatus_.empty())
+                {
+                    JLOG(j.fatal()) << "Invariant failed: " << sleStatus_.size()
+                                    << " domain object(s) affected by an "
+                                       "unauthorized transaction. "
+                                    << tx.getTxnType();
+                    return false;
+                }
+                return true;
+            }
+        }
+    }
+    else
+    {
+        if (tx.getTxnType() != ttPERMISSIONED_DOMAIN_SET || result != tesSUCCESS ||
+            sleStatus_.empty())
+            return true;
+        return check(sleStatus_[0], j);
+    }
+}
+
+}  // namespace xrpl

src/libxrpl/tx/invariants/VaultInvariant.cpp

@@ -0,0 +1,926 @@
+#include <xrpl/tx/invariants/VaultInvariant.h>
+//
+#include <xrpl/basics/Log.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/ledger/View.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Protocol.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STNumber.h>
+#include <xrpl/protocol/TxFormats.h>
+#include <xrpl/tx/invariants/InvariantCheckPrivilege.h>
+
+namespace xrpl {
+
+ValidVault::Vault
+ValidVault::Vault::make(SLE const& from)
+{
+    XRPL_ASSERT(from.getType() == ltVAULT, "ValidVault::Vault::make : from Vault object");
+
+    ValidVault::Vault self;
+    self.key = from.key();
+    self.asset = from.at(sfAsset);
+    self.pseudoId = from.getAccountID(sfAccount);
+    self.owner = from.at(sfOwner);
+    self.shareMPTID = from.getFieldH192(sfShareMPTID);
+    self.assetsTotal = from.at(sfAssetsTotal);
+    self.assetsAvailable = from.at(sfAssetsAvailable);
+    self.assetsMaximum = from.at(sfAssetsMaximum);
+    self.lossUnrealized = from.at(sfLossUnrealized);
+    return self;
+}
+
+ValidVault::Shares
+ValidVault::Shares::make(SLE const& from)
+{
+    XRPL_ASSERT(
+        from.getType() == ltMPTOKEN_ISSUANCE,
+        "ValidVault::Shares::make : from MPTokenIssuance object");
+
+    ValidVault::Shares self;
+    self.share = MPTIssue(makeMptID(from.getFieldU32(sfSequence), from.getAccountID(sfIssuer)));
+    self.sharesTotal = from.at(sfOutstandingAmount);
+    self.sharesMaximum = from[~sfMaximumAmount].value_or(maxMPTokenAmount);
+    return self;
+}
+
+void
+ValidVault::visitEntry(
+    bool isDelete,
+    std::shared_ptr<SLE const> const& before,
+    std::shared_ptr<SLE const> const& after)
+{
+    // If `before` is empty, this means an object is being created, in which
+    // case `isDelete` must be false. Otherwise `before` and `after` are set and
+    // `isDelete` indicates whether an object is being deleted or modified.
+    XRPL_ASSERT(
+        after != nullptr && (before != nullptr || !isDelete),
+        "xrpl::ValidVault::visitEntry : some object is available");
+
+    // Number balanceDelta will capture the difference (delta) between "before"
+    // state (zero if created) and "after" state (zero if destroyed), so the
+    // invariants can validate that the change in account balances matches the
+    // change in vault balances, stored to deltas_ at the end of this function.
+    Number balanceDelta{};
+
+    std::int8_t sign = 0;
+    if (before)
+    {
+        switch (before->getType())
+        {
+            case ltVAULT:
+                beforeVault_.push_back(Vault::make(*before));
+                break;
+            case ltMPTOKEN_ISSUANCE:
+                // At this moment we have no way of telling if this object holds
+                // vault shares or something else. Save it for finalize.
+                beforeMPTs_.push_back(Shares::make(*before));
+                balanceDelta = static_cast<std::int64_t>(before->getFieldU64(sfOutstandingAmount));
+                sign = 1;
+                break;
+            case ltMPTOKEN:
+                balanceDelta = static_cast<std::int64_t>(before->getFieldU64(sfMPTAmount));
+                sign = -1;
+                break;
+            case ltACCOUNT_ROOT:
+            case ltRIPPLE_STATE:
+                balanceDelta = before->getFieldAmount(sfBalance);
+                sign = -1;
+                break;
+            default:;
+        }
+    }
+
+    if (!isDelete && after)
+    {
+        switch (after->getType())
+        {
+            case ltVAULT:
+                afterVault_.push_back(Vault::make(*after));
+                break;
+            case ltMPTOKEN_ISSUANCE:
+                // At this moment we have no way of telling if this object holds
+                // vault shares or something else. Save it for finalize.
+                afterMPTs_.push_back(Shares::make(*after));
+                balanceDelta -=
+                    Number(static_cast<std::int64_t>(after->getFieldU64(sfOutstandingAmount)));
+                sign = 1;
+                break;
+            case ltMPTOKEN:
+                balanceDelta -= Number(static_cast<std::int64_t>(after->getFieldU64(sfMPTAmount)));
+                sign = -1;
+                break;
+            case ltACCOUNT_ROOT:
+            case ltRIPPLE_STATE:
+                balanceDelta -= Number(after->getFieldAmount(sfBalance));
+                sign = -1;
+                break;
+            default:;
+        }
+    }
+
+    uint256 const key = (before ? before->key() : after->key());
+    // Append to deltas if sign is non-zero, i.e. an object of an interesting
+    // type has been updated. A transaction may update an object even when
+    // its balance has not changed, e.g. transaction fee equals the amount
+    // transferred to the account. We intentionally do not compare balanceDelta
+    // against zero, to avoid missing such updates.
+    if (sign != 0)
+        deltas_[key] = balanceDelta * sign;
+}
+
+bool
+ValidVault::finalize(
+    STTx const& tx,
+    TER const ret,
+    XRPAmount const fee,
+    ReadView const& view,
+    beast::Journal const& j)
+{
+    bool const enforce = view.rules().enabled(featureSingleAssetVault);
+
+    if (!isTesSuccess(ret))
+        return true;  // Do not perform checks
+
+    if (afterVault_.empty() && beforeVault_.empty())
+    {
+        if (hasPrivilege(tx, mustModifyVault))
+        {
+            JLOG(j.fatal()) <<  //
+                "Invariant failed: vault operation succeeded without modifying "
+                "a vault";
+            XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : vault noop invariant");
+            return !enforce;
+        }
+
+        return true;  // Not a vault operation
+    }
+    else if (!(hasPrivilege(tx, mustModifyVault) || hasPrivilege(tx, mayModifyVault)))
+    {
+        JLOG(j.fatal()) <<  //
+            "Invariant failed: vault updated by a wrong transaction type";
+        XRPL_ASSERT(
+            enforce,
+            "xrpl::ValidVault::finalize : illegal vault transaction "
+            "invariant");
+        return !enforce;  // Also not a vault operation
+    }
+
+    if (beforeVault_.size() > 1 || afterVault_.size() > 1)
+    {
+        JLOG(j.fatal()) <<  //
+            "Invariant failed: vault operation updated more than single vault";
+        XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : single vault invariant");
+        return !enforce;  // That's all we can do here
+    }
+
+    auto const txnType = tx.getTxnType();
+
+    // We do special handling for ttVAULT_DELETE first, because it's the only
+    // vault-modifying transaction without an "after" state of the vault
+    if (afterVault_.empty())
+    {
+        if (txnType != ttVAULT_DELETE)
+        {
+            JLOG(j.fatal()) <<  //
+                "Invariant failed: vault deleted by a wrong transaction type";
+            XRPL_ASSERT(
+                enforce,
+                "xrpl::ValidVault::finalize : illegal vault deletion "
+                "invariant");
+            return !enforce;  // That's all we can do here
+        }
+
+        // Note, if afterVault_ is empty then we know that beforeVault_ is not
+        // empty, as enforced at the top of this function
+        auto const& beforeVault = beforeVault_[0];
+
+        // At this moment we only know a vault is being deleted and there
+        // might be some MPTokenIssuance objects which are deleted in the
+        // same transaction. Find the one matching this vault.
+        auto const deletedShares = [&]() -> std::optional<Shares> {
+            for (auto const& e : beforeMPTs_)
+            {
+                if (e.share.getMptID() == beforeVault.shareMPTID)
+                    return std::move(e);
+            }
+            return std::nullopt;
+        }();
+
+        if (!deletedShares)
+        {
+            JLOG(j.fatal()) << "Invariant failed: deleted vault must also "
+                               "delete shares";
+            XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : shares deletion invariant");
+            return !enforce;  // That's all we can do here
+        }
+
+        bool result = true;
+        if (deletedShares->sharesTotal != 0)
+        {
+            JLOG(j.fatal()) << "Invariant failed: deleted vault must have no "
+                               "shares outstanding";
+            result = false;
+        }
+        if (beforeVault.assetsTotal != zero)
+        {
+            JLOG(j.fatal()) << "Invariant failed: deleted vault must have no "
+                               "assets outstanding";
+            result = false;
+        }
+        if (beforeVault.assetsAvailable != zero)
+        {
+            JLOG(j.fatal()) << "Invariant failed: deleted vault must have no "
+                               "assets available";
+            result = false;
+        }
+
+        return result;
+    }
+    else if (txnType == ttVAULT_DELETE)
+    {
+        JLOG(j.fatal()) << "Invariant failed: vault deletion succeeded without "
+                           "deleting a vault";
+        XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : vault deletion invariant");
+        return !enforce;  // That's all we can do here
+    }
+
+    // Note, `afterVault_.empty()` is handled above
+    auto const& afterVault = afterVault_[0];
+    XRPL_ASSERT(
+        beforeVault_.empty() || beforeVault_[0].key == afterVault.key,
+        "xrpl::ValidVault::finalize : single vault operation");
+
+    auto const updatedShares = [&]() -> std::optional<Shares> {
+        // At this moment we only know that a vault is being updated and there
+        // might be some MPTokenIssuance objects which are also updated in the
+        // same transaction. Find the one matching the shares to this vault.
+        // Note, we expect updatedMPTs collection to be extremely small. For
+        // such collections linear search is faster than lookup.
+        for (auto const& e : afterMPTs_)
+        {
+            if (e.share.getMptID() == afterVault.shareMPTID)
+                return e;
+        }
+
+        auto const sleShares = view.read(keylet::mptIssuance(afterVault.shareMPTID));
+
+        return sleShares ? std::optional<Shares>(Shares::make(*sleShares)) : std::nullopt;
+    }();
+
+    bool result = true;
+
+    // Universal transaction checks
+    if (!beforeVault_.empty())
+    {
+        auto const& beforeVault = beforeVault_[0];
+        if (afterVault.asset != beforeVault.asset || afterVault.pseudoId != beforeVault.pseudoId ||
+            afterVault.shareMPTID != beforeVault.shareMPTID)
+        {
+            JLOG(j.fatal()) << "Invariant failed: violation of vault immutable data";
+            result = false;
+        }
+    }
+
+    if (!updatedShares)
+    {
+        JLOG(j.fatal()) << "Invariant failed: updated vault must have shares";
+        XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : vault has shares invariant");
+        return !enforce;  // That's all we can do here
+    }
+
+    if (updatedShares->sharesTotal == 0)
+    {
+        if (afterVault.assetsTotal != zero)
+        {
+            JLOG(j.fatal()) << "Invariant failed: updated zero sized "
+                               "vault must have no assets outstanding";
+            result = false;
+        }
+        if (afterVault.assetsAvailable != zero)
+        {
+            JLOG(j.fatal()) << "Invariant failed: updated zero sized "
+                               "vault must have no assets available";
+            result = false;
+        }
+    }
+    else if (updatedShares->sharesTotal > updatedShares->sharesMaximum)
+    {
+        JLOG(j.fatal())  //
+            << "Invariant failed: updated shares must not exceed maximum "
+            << updatedShares->sharesMaximum;
+        result = false;
+    }
+
+    if (afterVault.assetsAvailable < zero)
+    {
+        JLOG(j.fatal()) << "Invariant failed: assets available must be positive";
+        result = false;
+    }
+
+    if (afterVault.assetsAvailable > afterVault.assetsTotal)
+    {
+        JLOG(j.fatal()) << "Invariant failed: assets available must "
+                           "not be greater than assets outstanding";
+        result = false;
+    }
+    else if (afterVault.lossUnrealized > afterVault.assetsTotal - afterVault.assetsAvailable)
+    {
+        JLOG(j.fatal())  //
+            << "Invariant failed: loss unrealized must not exceed "
+               "the difference between assets outstanding and available";
+        result = false;
+    }
+
+    if (afterVault.assetsTotal < zero)
+    {
+        JLOG(j.fatal()) << "Invariant failed: assets outstanding must be positive";
+        result = false;
+    }
+
+    if (afterVault.assetsMaximum < zero)
+    {
+        JLOG(j.fatal()) << "Invariant failed: assets maximum must be positive";
+        result = false;
+    }
+
+    // Thanks to this check we can simply do `assert(!beforeVault_.empty()` when
+    // enforcing invariants on transaction types other than ttVAULT_CREATE
+    if (beforeVault_.empty() && txnType != ttVAULT_CREATE)
+    {
+        JLOG(j.fatal()) <<  //
+            "Invariant failed: vault created by a wrong transaction type";
+        XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : vault creation invariant");
+        return !enforce;  // That's all we can do here
+    }
+
+    if (!beforeVault_.empty() && afterVault.lossUnrealized != beforeVault_[0].lossUnrealized &&
+        txnType != ttLOAN_MANAGE && txnType != ttLOAN_PAY)
+    {
+        JLOG(j.fatal()) <<  //
+            "Invariant failed: vault transaction must not change loss "
+            "unrealized";
+        result = false;
+    }
+
+    auto const beforeShares = [&]() -> std::optional<Shares> {
+        if (beforeVault_.empty())
+            return std::nullopt;
+        auto const& beforeVault = beforeVault_[0];
+
+        for (auto const& e : beforeMPTs_)
+        {
+            if (e.share.getMptID() == beforeVault.shareMPTID)
+                return std::move(e);
+        }
+        return std::nullopt;
+    }();
+
+    if (!beforeShares &&
+        (tx.getTxnType() == ttVAULT_DEPOSIT ||   //
+         tx.getTxnType() == ttVAULT_WITHDRAW ||  //
+         tx.getTxnType() == ttVAULT_CLAWBACK))
+    {
+        JLOG(j.fatal()) << "Invariant failed: vault operation succeeded "
+                           "without updating shares";
+        XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : shares noop invariant");
+        return !enforce;  // That's all we can do here
+    }
+
+    auto const& vaultAsset = afterVault.asset;
+    auto const deltaAssets = [&](AccountID const& id) -> std::optional<Number> {
+        auto const get =  //
+            [&](auto const& it, std::int8_t sign = 1) -> std::optional<Number> {
+            if (it == deltas_.end())
+                return std::nullopt;
+
+            return it->second * sign;
+        };
+
+        return std::visit(
+            [&]<typename TIss>(TIss const& issue) {
+                if constexpr (std::is_same_v<TIss, Issue>)
+                {
+                    if (isXRP(issue))
+                        return get(deltas_.find(keylet::account(id).key));
+                    return get(
+                        deltas_.find(keylet::line(id, issue).key), id > issue.getIssuer() ? -1 : 1);
+                }
+                else if constexpr (std::is_same_v<TIss, MPTIssue>)
+                {
+                    return get(deltas_.find(keylet::mptoken(issue.getMptID(), id).key));
+                }
+            },
+            vaultAsset.value());
+    };
+    auto const deltaAssetsTxAccount = [&]() -> std::optional<Number> {
+        auto ret = deltaAssets(tx[sfAccount]);
+        // Nothing returned or not XRP transaction
+        if (!ret.has_value() || !vaultAsset.native())
+            return ret;
+
+        // Delegated transaction; no need to compensate for fees
+        if (auto const delegate = tx[~sfDelegate];
+            delegate.has_value() && *delegate != tx[sfAccount])
+            return ret;
+
+        *ret += fee.drops();
+        if (*ret == zero)
+            return std::nullopt;
+
+        return ret;
+    };
+    auto const deltaShares = [&](AccountID const& id) -> std::optional<Number> {
+        auto const it = [&]() {
+            if (id == afterVault.pseudoId)
+                return deltas_.find(keylet::mptIssuance(afterVault.shareMPTID).key);
+            return deltas_.find(keylet::mptoken(afterVault.shareMPTID, id).key);
+        }();
+
+        return it != deltas_.end() ? std::optional<Number>(it->second) : std::nullopt;
+    };
+
+    auto const vaultHoldsNoAssets = [&](Vault const& vault) {
+        return vault.assetsAvailable == 0 && vault.assetsTotal == 0;
+    };
+
+    // Technically this does not need to be a lambda, but it's more
+    // convenient thanks to early "return false"; the not-so-nice
+    // alternatives are several layers of nested if/else or more complex
+    // (i.e. brittle) if statements.
+    result &= [&]() {
+        switch (txnType)
+        {
+            case ttVAULT_CREATE: {
+                bool result = true;
+
+                if (!beforeVault_.empty())
+                {
+                    JLOG(j.fatal())  //
+                        << "Invariant failed: create operation must not have "
+                           "updated a vault";
+                    result = false;
+                }
+
+                if (afterVault.assetsAvailable != zero || afterVault.assetsTotal != zero ||
+                    afterVault.lossUnrealized != zero || updatedShares->sharesTotal != 0)
+                {
+                    JLOG(j.fatal())  //
+                        << "Invariant failed: created vault must be empty";
+                    result = false;
+                }
+
+                if (afterVault.pseudoId != updatedShares->share.getIssuer())
+                {
+                    JLOG(j.fatal())  //
+                        << "Invariant failed: shares issuer and vault "
+                           "pseudo-account must be the same";
+                    result = false;
+                }
+
+                auto const sleSharesIssuer =
+                    view.read(keylet::account(updatedShares->share.getIssuer()));
+                if (!sleSharesIssuer)
+                {
+                    JLOG(j.fatal())  //
+                        << "Invariant failed: shares issuer must exist";
+                    return false;
+                }
+
+                if (!isPseudoAccount(sleSharesIssuer))
+                {
+                    JLOG(j.fatal())  //
+                        << "Invariant failed: shares issuer must be a "
+                           "pseudo-account";
+                    result = false;
+                }
+
+                if (auto const vaultId = (*sleSharesIssuer)[~sfVaultID];
+                    !vaultId || *vaultId != afterVault.key)
+                {
+                    JLOG(j.fatal())  //
+                        << "Invariant failed: shares issuer pseudo-account "
+                           "must point back to the vault";
+                    result = false;
+                }
+
+                return result;
+            }
+            case ttVAULT_SET: {
+                bool result = true;
+
+                XRPL_ASSERT(
+                    !beforeVault_.empty(), "xrpl::ValidVault::finalize : set updated a vault");
+                auto const& beforeVault = beforeVault_[0];
+
+                auto const vaultDeltaAssets = deltaAssets(afterVault.pseudoId);
+                if (vaultDeltaAssets)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: set must not change vault balance";
+                    result = false;
+                }
+
+                if (beforeVault.assetsTotal != afterVault.assetsTotal)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: set must not change assets "
+                        "outstanding";
+                    result = false;
+                }
+
+                if (afterVault.assetsMaximum > zero &&
+                    afterVault.assetsTotal > afterVault.assetsMaximum)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: set assets outstanding must not "
+                        "exceed assets maximum";
+                    result = false;
+                }
+
+                if (beforeVault.assetsAvailable != afterVault.assetsAvailable)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: set must not change assets "
+                        "available";
+                    result = false;
+                }
+
+                if (beforeShares && updatedShares &&
+                    beforeShares->sharesTotal != updatedShares->sharesTotal)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: set must not change shares "
+                        "outstanding";
+                    result = false;
+                }
+
+                return result;
+            }
+            case ttVAULT_DEPOSIT: {
+                bool result = true;
+
+                XRPL_ASSERT(
+                    !beforeVault_.empty(), "xrpl::ValidVault::finalize : deposit updated a vault");
+                auto const& beforeVault = beforeVault_[0];
+
+                auto const vaultDeltaAssets = deltaAssets(afterVault.pseudoId);
+
+                if (!vaultDeltaAssets)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must change vault balance";
+                    return false;  // That's all we can do
+                }
+
+                if (*vaultDeltaAssets > tx[sfAmount])
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must not change vault "
+                        "balance by more than deposited amount";
+                    result = false;
+                }
+
+                if (*vaultDeltaAssets <= zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must increase vault balance";
+                    result = false;
+                }
+
+                // Any payments (including deposits) made by the issuer
+                // do not change their balance, but create funds instead.
+                bool const issuerDeposit = [&]() -> bool {
+                    if (vaultAsset.native())
+                        return false;
+                    return tx[sfAccount] == vaultAsset.getIssuer();
+                }();
+
+                if (!issuerDeposit)
+                {
+                    auto const accountDeltaAssets = deltaAssetsTxAccount();
+                    if (!accountDeltaAssets)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: deposit must change depositor "
+                            "balance";
+                        return false;
+                    }
+
+                    if (*accountDeltaAssets >= zero)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: deposit must decrease depositor "
+                            "balance";
+                        result = false;
+                    }
+
+                    if (*accountDeltaAssets * -1 != *vaultDeltaAssets)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: deposit must change vault and "
+                            "depositor balance by equal amount";
+                        result = false;
+                    }
+                }
+
+                if (afterVault.assetsMaximum > zero &&
+                    afterVault.assetsTotal > afterVault.assetsMaximum)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit assets outstanding must not "
+                        "exceed assets maximum";
+                    result = false;
+                }
+
+                auto const accountDeltaShares = deltaShares(tx[sfAccount]);
+                if (!accountDeltaShares)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must change depositor "
+                        "shares";
+                    return false;  // That's all we can do
+                }
+
+                if (*accountDeltaShares <= zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must increase depositor "
+                        "shares";
+                    result = false;
+                }
+
+                auto const vaultDeltaShares = deltaShares(afterVault.pseudoId);
+                if (!vaultDeltaShares || *vaultDeltaShares == zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must change vault shares";
+                    return false;  // That's all we can do
+                }
+
+                if (*vaultDeltaShares * -1 != *accountDeltaShares)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: deposit must change depositor and "
+                        "vault shares by equal amount";
+                    result = false;
+                }
+
+                if (beforeVault.assetsTotal + *vaultDeltaAssets != afterVault.assetsTotal)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: deposit and assets "
+                                       "outstanding must add up";
+                    result = false;
+                }
+                if (beforeVault.assetsAvailable + *vaultDeltaAssets != afterVault.assetsAvailable)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: deposit and assets "
+                                       "available must add up";
+                    result = false;
+                }
+
+                return result;
+            }
+            case ttVAULT_WITHDRAW: {
+                bool result = true;
+
+                XRPL_ASSERT(
+                    !beforeVault_.empty(),
+                    "xrpl::ValidVault::finalize : withdrawal updated a "
+                    "vault");
+                auto const& beforeVault = beforeVault_[0];
+
+                auto const vaultDeltaAssets = deltaAssets(afterVault.pseudoId);
+
+                if (!vaultDeltaAssets)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: withdrawal must "
+                                       "change vault balance";
+                    return false;  // That's all we can do
+                }
+
+                if (*vaultDeltaAssets >= zero)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: withdrawal must "
+                                       "decrease vault balance";
+                    result = false;
+                }
+
+                // Any payments (including withdrawal) going to the issuer
+                // do not change their balance, but destroy funds instead.
+                bool const issuerWithdrawal = [&]() -> bool {
+                    if (vaultAsset.native())
+                        return false;
+                    auto const destination = tx[~sfDestination].value_or(tx[sfAccount]);
+                    return destination == vaultAsset.getIssuer();
+                }();
+
+                if (!issuerWithdrawal)
+                {
+                    auto const accountDeltaAssets = deltaAssetsTxAccount();
+                    auto const otherAccountDelta = [&]() -> std::optional<Number> {
+                        if (auto const destination = tx[~sfDestination];
+                            destination && *destination != tx[sfAccount])
+                            return deltaAssets(*destination);
+                        return std::nullopt;
+                    }();
+
+                    if (accountDeltaAssets.has_value() == otherAccountDelta.has_value())
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: withdrawal must change one "
+                            "destination balance";
+                        return false;
+                    }
+
+                    auto const destinationDelta =  //
+                        accountDeltaAssets ? *accountDeltaAssets : *otherAccountDelta;
+
+                    if (destinationDelta <= zero)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: withdrawal must increase "
+                            "destination balance";
+                        result = false;
+                    }
+
+                    if (*vaultDeltaAssets * -1 != destinationDelta)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: withdrawal must change vault "
+                            "and destination balance by equal amount";
+                        result = false;
+                    }
+                }
+
+                auto const accountDeltaShares = deltaShares(tx[sfAccount]);
+                if (!accountDeltaShares)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: withdrawal must change depositor "
+                        "shares";
+                    return false;
+                }
+
+                if (*accountDeltaShares >= zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: withdrawal must decrease depositor "
+                        "shares";
+                    result = false;
+                }
+
+                auto const vaultDeltaShares = deltaShares(afterVault.pseudoId);
+                if (!vaultDeltaShares || *vaultDeltaShares == zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: withdrawal must change vault shares";
+                    return false;  // That's all we can do
+                }
+
+                if (*vaultDeltaShares * -1 != *accountDeltaShares)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: withdrawal must change depositor "
+                        "and vault shares by equal amount";
+                    result = false;
+                }
+
+                // Note, vaultBalance is negative (see check above)
+                if (beforeVault.assetsTotal + *vaultDeltaAssets != afterVault.assetsTotal)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: withdrawal and "
+                                       "assets outstanding must add up";
+                    result = false;
+                }
+
+                if (beforeVault.assetsAvailable + *vaultDeltaAssets != afterVault.assetsAvailable)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: withdrawal and "
+                                       "assets available must add up";
+                    result = false;
+                }
+
+                return result;
+            }
+            case ttVAULT_CLAWBACK: {
+                bool result = true;
+
+                XRPL_ASSERT(
+                    !beforeVault_.empty(), "xrpl::ValidVault::finalize : clawback updated a vault");
+                auto const& beforeVault = beforeVault_[0];
+
+                if (vaultAsset.native() || vaultAsset.getIssuer() != tx[sfAccount])
+                {
+                    // The owner can use clawback to force-burn shares when the
+                    // vault is empty but there are outstanding shares
+                    if (!(beforeShares && beforeShares->sharesTotal > 0 &&
+                          vaultHoldsNoAssets(beforeVault) && beforeVault.owner == tx[sfAccount]))
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: clawback may only be performed "
+                            "by the asset issuer, or by the vault owner of an "
+                            "empty vault";
+                        return false;  // That's all we can do
+                    }
+                }
+
+                auto const vaultDeltaAssets = deltaAssets(afterVault.pseudoId);
+                if (vaultDeltaAssets)
+                {
+                    if (*vaultDeltaAssets >= zero)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: clawback must decrease vault "
+                            "balance";
+                        result = false;
+                    }
+
+                    if (beforeVault.assetsTotal + *vaultDeltaAssets != afterVault.assetsTotal)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: clawback and assets outstanding "
+                            "must add up";
+                        result = false;
+                    }
+
+                    if (beforeVault.assetsAvailable + *vaultDeltaAssets !=
+                        afterVault.assetsAvailable)
+                    {
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: clawback and assets available "
+                            "must add up";
+                        result = false;
+                    }
+                }
+                else if (!vaultHoldsNoAssets(beforeVault))
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: clawback must change vault balance";
+                    return false;  // That's all we can do
+                }
+
+                auto const accountDeltaShares = deltaShares(tx[sfHolder]);
+                if (!accountDeltaShares)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: clawback must change holder shares";
+                    return false;  // That's all we can do
+                }
+
+                if (*accountDeltaShares >= zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: clawback must decrease holder "
+                        "shares";
+                    result = false;
+                }
+
+                auto const vaultDeltaShares = deltaShares(afterVault.pseudoId);
+                if (!vaultDeltaShares || *vaultDeltaShares == zero)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: clawback must change vault shares";
+                    return false;  // That's all we can do
+                }
+
+                if (*vaultDeltaShares * -1 != *accountDeltaShares)
+                {
+                    JLOG(j.fatal()) <<  //
+                        "Invariant failed: clawback must change holder and "
+                        "vault shares by equal amount";
+                    result = false;
+                }
+
+                return result;
+            }
+
+            case ttLOAN_SET:
+            case ttLOAN_MANAGE:
+            case ttLOAN_PAY: {
+                // TBD
+                return true;
+            }
+
+            default:
+                // LCOV_EXCL_START
+                UNREACHABLE("xrpl::ValidVault::finalize : unknown transaction type");
+                return false;
+                // LCOV_EXCL_STOP
+        }
+    }();
+
+    if (!result)
+    {
+        // The comment at the top of this file starting with "assert(enforce)"
+        // explains this assert.
+        XRPL_ASSERT(enforce, "xrpl::ValidVault::finalize : vault invariants");
+        return !enforce;
+    }
+
+    return true;
+}
+
+}  // namespace xrpl

src/libxrpl/tx/transactors/PermissionedDomain/PermissionedDomainSet.cpp

@@ -1,10 +1,9 @@
+#include <xrpl/tx/transactors/PermissionedDomain/PermissionedDomainSet.h>
+//
 #include <xrpl/ledger/CredentialHelpers.h>
 #include <xrpl/ledger/View.h>
 #include <xrpl/protocol/STObject.h>
 #include <xrpl/protocol/TxFlags.h>
-#include <xrpl/tx/transactors/PermissionedDomain/PermissionedDomainSet.h>
-
-#include <optional>
 
 namespace xrpl {
 

src/test/app/Path_test.cpp

@@ -8,7 +8,6 @@
 #include <xrpld/rpc/detail/Tuning.h>
 
 #include <xrpl/beast/unit_test.h>
-#include <xrpl/core/CoroTask.h>
 #include <xrpl/core/JobQueue.h>
 #include <xrpl/json/json_reader.h>
 #include <xrpl/protocol/ApiVersion.h>
@@ -132,6 +131,7 @@ public:
              c,
              Role::USER,
              {},
+             {},
              RPC::apiVersionIfUnspecified},
             {},
             {}};
@@ -155,11 +155,11 @@ public:
 
         Json::Value result;
         gate g;
-        app.getJobQueue().postCoroTask(jtCLIENT, "RPC-Client", [&](auto) -> CoroTask<void> {
+        app.getJobQueue().postCoro(jtCLIENT, "RPC-Client", [&](auto const& coro) {
             context.params = std::move(params);
+            context.coro = coro;
             RPC::doCommand(context, result);
             g.signal();
-            co_return;
         });
 
         using namespace std::chrono_literals;
@@ -240,27 +240,28 @@ public:
              c,
              Role::USER,
              {},
+             {},
              RPC::apiVersionIfUnspecified},
             {},
             {}};
         Json::Value result;
         gate g;
         // Test RPC::Tuning::max_src_cur source currencies.
-        app.getJobQueue().postCoroTask(jtCLIENT, "RPC-Client", [&](auto) -> CoroTask<void> {
+        app.getJobQueue().postCoro(jtCLIENT, "RPC-Client", [&](auto const& coro) {
             context.params = rpf(Account("alice"), Account("bob"), RPC::Tuning::max_src_cur);
+            context.coro = coro;
             RPC::doCommand(context, result);
             g.signal();
-            co_return;
         });
         BEAST_EXPECT(g.wait_for(5s));
         BEAST_EXPECT(!result.isMember(jss::error));
 
         // Test more than RPC::Tuning::max_src_cur source currencies.
-        app.getJobQueue().postCoroTask(jtCLIENT, "RPC-Client", [&](auto) -> CoroTask<void> {
+        app.getJobQueue().postCoro(jtCLIENT, "RPC-Client", [&](auto const& coro) {
             context.params = rpf(Account("alice"), Account("bob"), RPC::Tuning::max_src_cur + 1);
+            context.coro = coro;
             RPC::doCommand(context, result);
             g.signal();
-            co_return;
         });
         BEAST_EXPECT(g.wait_for(5s));
         BEAST_EXPECT(result.isMember(jss::error));
@@ -268,22 +269,22 @@ public:
         // Test RPC::Tuning::max_auto_src_cur source currencies.
         for (auto i = 0; i < (RPC::Tuning::max_auto_src_cur - 1); ++i)
             env.trust(Account("alice")[std::to_string(i + 100)](100), "bob");
-        app.getJobQueue().postCoroTask(jtCLIENT, "RPC-Client", [&](auto) -> CoroTask<void> {
+        app.getJobQueue().postCoro(jtCLIENT, "RPC-Client", [&](auto const& coro) {
             context.params = rpf(Account("alice"), Account("bob"), 0);
+            context.coro = coro;
             RPC::doCommand(context, result);
             g.signal();
-            co_return;
         });
         BEAST_EXPECT(g.wait_for(5s));
         BEAST_EXPECT(!result.isMember(jss::error));
 
         // Test more than RPC::Tuning::max_auto_src_cur source currencies.
         env.trust(Account("alice")["AUD"](100), "bob");
-        app.getJobQueue().postCoroTask(jtCLIENT, "RPC-Client", [&](auto) -> CoroTask<void> {
+        app.getJobQueue().postCoro(jtCLIENT, "RPC-Client", [&](auto const& coro) {
             context.params = rpf(Account("alice"), Account("bob"), 0);
+            context.coro = coro;
             RPC::doCommand(context, result);
             g.signal();
-            co_return;
         });
         BEAST_EXPECT(g.wait_for(5s));
         BEAST_EXPECT(result.isMember(jss::error));

src/test/core/CoroTask_test.cpp

@@ -1,537 +0,0 @@
-#include <test/jtx.h>
-
-#include <xrpl/core/JobQueue.h>
-#include <xrpl/core/JobQueueAwaiter.h>
-
-#include <chrono>
-#include <mutex>
-
-namespace xrpl {
-namespace test {
-
-/**
- * Test suite for the C++20 coroutine primitives: CoroTask, CoroTaskRunner,
- * and JobQueueAwaiter.
- *
- * Dependency Diagram
- * ==================
- *
- *   CoroTask_test
- *   +-------------------------------------------------+
- *   | + gate (inner class) : condition_variable helper |
- *   +-------------------------------------------------+
- *          |  uses
- *          v
- *   jtx::Env  -->  JobQueue::postCoroTask()
- *                       |
- *                       +-- CoroTaskRunner (suspend / post / resume)
- *                       +-- CoroTask<void> / CoroTask<T>
- *                       +-- JobQueueAwaiter
- *
- * Test Coverage Matrix
- * ====================
- *
- *   Test                      | Primitives exercised
- *   --------------------------+----------------------------------------------
- *   testVoidCompletion        | CoroTask<void> basic lifecycle
- *   testCorrectOrder          | suspend() -> join() -> post() -> complete
- *   testIncorrectOrder        | post() before suspend() (race-safe path)
- *   testJobQueueAwaiter       | JobQueueAwaiter suspend + auto-repost
- *   testThreadSpecificStorage | LocalValue isolation across coroutines
- *   testExceptionPropagation  | unhandled_exception() in promise_type
- *   testMultipleYields        | N sequential suspend/resume cycles
- *   testValueReturn           | CoroTask<T> co_return value
- *   testValueException        | CoroTask<T> exception via co_await
- *   testValueChaining         | nested CoroTask<T> -> CoroTask<T>
- *   testShutdownRejection     | postCoroTask returns nullptr when stopping
- */
-class CoroTask_test : public beast::unit_test::suite
-{
-public:
-    /**
-     * Simple one-shot gate for synchronizing between test thread
-     * and coroutine worker threads. signal() sets the flag;
-     * wait_for() blocks until signaled or timeout.
-     */
-    class gate
-    {
-    private:
-        std::condition_variable cv_;
-        std::mutex mutex_;
-        bool signaled_ = false;
-
-    public:
-        /**
-         * Block until signaled or timeout expires.
-         *
-         * @param rel_time Maximum duration to wait
-         *
-         * @return true if signaled before timeout
-         */
-        template <class Rep, class Period>
-        bool
-        wait_for(std::chrono::duration<Rep, Period> const& rel_time)
-        {
-            std::unique_lock<std::mutex> lk(mutex_);
-            auto b = cv_.wait_for(lk, rel_time, [this] { return signaled_; });
-            signaled_ = false;
-            return b;
-        }
-
-        /**
-         * Signal the gate, waking any waiting thread.
-         */
-        void
-        signal()
-        {
-            std::lock_guard lk(mutex_);
-            signaled_ = true;
-            cv_.notify_all();
-        }
-    };
-
-    // NOTE: All coroutine lambdas passed to postCoroTask use explicit
-    // pointer-by-value captures instead of [&] to work around a GCC 14
-    // bug where reference captures in coroutine lambdas are corrupted
-    // in the coroutine frame.
-
-    /**
-     * CoroTask<void> runs to completion and runner becomes non-runnable.
-     */
-    void
-    testVoidCompletion()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("void completion");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [gp = &g](auto) -> CoroTask<void> {
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-        BEAST_EXPECT(g.wait_for(5s));
-        runner->join();
-        BEAST_EXPECT(!runner->runnable());
-    }
-
-    /**
-     * Correct order: suspend, join, post, complete.
-     * Mirrors existing Coroutine_test::correct_order.
-     */
-    void
-    testCorrectOrder()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("correct order");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g1, g2;
-        std::shared_ptr<JobQueue::CoroTaskRunner> r;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT,
-            "CoroTaskTest",
-            [rp = &r, g1p = &g1, g2p = &g2](auto runner) -> CoroTask<void> {
-                *rp = runner;
-                g1p->signal();
-                co_await runner->suspend();
-                g2p->signal();
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-        BEAST_EXPECT(g1.wait_for(5s));
-        runner->join();
-        runner->post();
-        BEAST_EXPECT(g2.wait_for(5s));
-        runner->join();
-    }
-
-    /**
-     * Incorrect order: post() before suspend(). Verifies the
-     * race-safe path. Mirrors Coroutine_test::incorrect_order.
-     */
-    void
-    testIncorrectOrder()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("incorrect order");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [gp = &g](auto runner) -> CoroTask<void> {
-                runner->post();
-                co_await runner->suspend();
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(g.wait_for(5s));
-    }
-
-    /**
-     * JobQueueAwaiter suspend + auto-repost across multiple yield points.
-     */
-    void
-    testJobQueueAwaiter()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("JobQueueAwaiter");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        int step = 0;
-        env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [sp = &step, gp = &g](auto runner) -> CoroTask<void> {
-                *sp = 1;
-                co_await JobQueueAwaiter{runner};
-                *sp = 2;
-                co_await JobQueueAwaiter{runner};
-                *sp = 3;
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(g.wait_for(5s));
-        BEAST_EXPECT(step == 3);
-    }
-
-    /**
-     * Per-coroutine LocalValue isolation. Each coroutine sees its own
-     * copy of thread-local state. Mirrors Coroutine_test::thread_specific_storage.
-     */
-    void
-    testThreadSpecificStorage()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("thread specific storage");
-        Env env(*this);
-
-        auto& jq = env.app().getJobQueue();
-
-        static int const N = 4;
-        std::array<std::shared_ptr<JobQueue::CoroTaskRunner>, N> a;
-
-        LocalValue<int> lv(-1);
-        BEAST_EXPECT(*lv == -1);
-
-        gate g;
-        jq.addJob(jtCLIENT, "LocalValTest", [&]() {
-            this->BEAST_EXPECT(*lv == -1);
-            *lv = -2;
-            this->BEAST_EXPECT(*lv == -2);
-            g.signal();
-        });
-        BEAST_EXPECT(g.wait_for(5s));
-        BEAST_EXPECT(*lv == -1);
-
-        for (int i = 0; i < N; ++i)
-        {
-            jq.postCoroTask(
-                jtCLIENT,
-                "CoroTaskTest",
-                [this, ap = &a, gp = &g, lvp = &lv, id = i](auto runner) -> CoroTask<void> {
-                    (*ap)[id] = runner;
-                    gp->signal();
-                    co_await runner->suspend();
-
-                    this->BEAST_EXPECT(**lvp == -1);
-                    **lvp = id;
-                    this->BEAST_EXPECT(**lvp == id);
-                    gp->signal();
-                    co_await runner->suspend();
-
-                    this->BEAST_EXPECT(**lvp == id);
-                    co_return;
-                });
-            BEAST_EXPECT(g.wait_for(5s));
-            a[i]->join();
-        }
-        for (auto const& r : a)
-        {
-            r->post();
-            BEAST_EXPECT(g.wait_for(5s));
-            r->join();
-        }
-        for (auto const& r : a)
-        {
-            r->post();
-            r->join();
-        }
-
-        jq.addJob(jtCLIENT, "LocalValTest", [&]() {
-            this->BEAST_EXPECT(*lv == -2);
-            g.signal();
-        });
-        BEAST_EXPECT(g.wait_for(5s));
-        BEAST_EXPECT(*lv == -1);
-    }
-
-    /**
-     * Exception thrown in coroutine body is caught by
-     * promise_type::unhandled_exception(). Coroutine completes.
-     */
-    void
-    testExceptionPropagation()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("exception propagation");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [gp = &g](auto) -> CoroTask<void> {
-                gp->signal();
-                throw std::runtime_error("test exception");
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-        BEAST_EXPECT(g.wait_for(5s));
-        runner->join();
-        // The exception is caught by promise_type::unhandled_exception()
-        // and the coroutine is considered done
-        BEAST_EXPECT(!runner->runnable());
-    }
-
-    /**
-     * Multiple sequential suspend/resume cycles via co_await.
-     */
-    void
-    testMultipleYields()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("multiple yields");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        int counter = 0;
-        std::shared_ptr<JobQueue::CoroTaskRunner> r;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT,
-            "CoroTaskTest",
-            [rp = &r, cp = &counter, gp = &g](auto runner) -> CoroTask<void> {
-                *rp = runner;
-                ++(*cp);
-                gp->signal();
-                co_await runner->suspend();
-                ++(*cp);
-                gp->signal();
-                co_await runner->suspend();
-                ++(*cp);
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-
-        BEAST_EXPECT(g.wait_for(5s));
-        BEAST_EXPECT(counter == 1);
-        runner->join();
-
-        runner->post();
-        BEAST_EXPECT(g.wait_for(5s));
-        BEAST_EXPECT(counter == 2);
-        runner->join();
-
-        runner->post();
-        BEAST_EXPECT(g.wait_for(5s));
-        BEAST_EXPECT(counter == 3);
-        runner->join();
-        BEAST_EXPECT(!runner->runnable());
-    }
-
-    /**
-     * CoroTask<T> returns a value via co_return. Outer coroutine
-     * extracts it with co_await.
-     */
-    void
-    testValueReturn()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("value return");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        int result = 0;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [rp = &result, gp = &g](auto) -> CoroTask<void> {
-                auto inner = []() -> CoroTask<int> { co_return 42; };
-                *rp = co_await inner();
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-        BEAST_EXPECT(g.wait_for(5s));
-        runner->join();
-        BEAST_EXPECT(result == 42);
-        BEAST_EXPECT(!runner->runnable());
-    }
-
-    /**
-     * CoroTask<T> propagates exceptions from inner coroutines.
-     * Outer coroutine catches via try/catch around co_await.
-     */
-    void
-    testValueException()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("value exception");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        bool caught = false;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [cp = &caught, gp = &g](auto) -> CoroTask<void> {
-                auto inner = []() -> CoroTask<int> {
-                    throw std::runtime_error("inner error");
-                    co_return 0;
-                };
-                try
-                {
-                    co_await inner();
-                }
-                catch (std::runtime_error const& e)
-                {
-                    *cp = true;
-                }
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-        BEAST_EXPECT(g.wait_for(5s));
-        runner->join();
-        BEAST_EXPECT(caught);
-        BEAST_EXPECT(!runner->runnable());
-    }
-
-    /**
-     * CoroTask<T> chaining. Nested value-returning coroutines
-     * compose via co_await.
-     */
-    void
-    testValueChaining()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("value chaining");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        gate g;
-        int result = 0;
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [rp = &result, gp = &g](auto) -> CoroTask<void> {
-                auto add = [](int a, int b) -> CoroTask<int> { co_return a + b; };
-                auto mul = [add](int a, int b) -> CoroTask<int> {
-                    int sum = co_await add(a, b);
-                    co_return sum * 2;
-                };
-                *rp = co_await mul(3, 4);
-                gp->signal();
-                co_return;
-            });
-        BEAST_EXPECT(runner);
-        BEAST_EXPECT(g.wait_for(5s));
-        runner->join();
-        BEAST_EXPECT(result == 14);  // (3 + 4) * 2
-        BEAST_EXPECT(!runner->runnable());
-    }
-
-    /**
-     * postCoroTask returns nullptr when JobQueue is stopping.
-     */
-    void
-    testShutdownRejection()
-    {
-        using namespace std::chrono_literals;
-        using namespace jtx;
-
-        testcase("shutdown rejection");
-
-        Env env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->FORCE_MULTI_THREAD = true;
-            return cfg;
-        }));
-
-        // Stop the JobQueue
-        env.app().getJobQueue().stop();
-
-        auto runner = env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTaskTest", [](auto) -> CoroTask<void> { co_return; });
-        BEAST_EXPECT(!runner);
-    }
-
-    void
-    run() override
-    {
-        testVoidCompletion();
-        testCorrectOrder();
-        testIncorrectOrder();
-        testJobQueueAwaiter();
-        testThreadSpecificStorage();
-        testExceptionPropagation();
-        testMultipleYields();
-        testValueReturn();
-        testValueException();
-        testValueChaining();
-        testShutdownRejection();
-    }
-};
-
-BEAST_DEFINE_TESTSUITE(CoroTask, core, xrpl);
-
-}  // namespace test
-}  // namespace xrpl

src/test/core/Coroutine_test.cpp

@@ -40,11 +40,6 @@ public:
         }
     };
 
-    // NOTE: All coroutine lambdas passed to postCoroTask use explicit
-    // pointer-by-value captures instead of [&] to work around a GCC 14
-    // bug where reference captures in coroutine lambdas are corrupted
-    // in the coroutine frame.
-
     void
     correct_order()
     {
@@ -59,15 +54,13 @@ public:
         }));
 
         gate g1, g2;
-        std::shared_ptr<JobQueue::CoroTaskRunner> c;
-        env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTest", [cp = &c, g1p = &g1, g2p = &g2](auto runner) -> CoroTask<void> {
-                *cp = runner;
-                g1p->signal();
-                co_await runner->suspend();
-                g2p->signal();
-                co_return;
-            });
+        std::shared_ptr<JobQueue::Coro> c;
+        env.app().getJobQueue().postCoro(jtCLIENT, "CoroTest", [&](auto const& cr) {
+            c = cr;
+            g1.signal();
+            c->yield();
+            g2.signal();
+        });
         BEAST_EXPECT(g1.wait_for(5s));
         c->join();
         c->post();
@@ -88,17 +81,11 @@ public:
         }));
 
         gate g;
-        env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTest", [gp = &g](auto runner) -> CoroTask<void> {
-                // Schedule a resume before suspending.  The posted job
-                // cannot actually call resume() until the current resume()
-                // releases CoroTaskRunner::mutex_, which only happens after
-                // the coroutine suspends at co_await.
-                runner->post();
-                co_await runner->suspend();
-                gp->signal();
-                co_return;
-            });
+        env.app().getJobQueue().postCoro(jtCLIENT, "CoroTest", [&](auto const& c) {
+            c->post();
+            c->yield();
+            g.signal();
+        });
         BEAST_EXPECT(g.wait_for(5s));
     }
 
@@ -114,7 +101,7 @@ public:
         auto& jq = env.app().getJobQueue();
 
         static int const N = 4;
-        std::array<std::shared_ptr<JobQueue::CoroTaskRunner>, N> a;
+        std::array<std::shared_ptr<JobQueue::Coro>, N> a;
 
         LocalValue<int> lv(-1);
         BEAST_EXPECT(*lv == -1);
@@ -131,23 +118,19 @@ public:
 
         for (int i = 0; i < N; ++i)
         {
-            jq.postCoroTask(
-                jtCLIENT,
-                "CoroTest",
-                [this, ap = &a, gp = &g, lvp = &lv, id = i](auto runner) -> CoroTask<void> {
-                    (*ap)[id] = runner;
-                    gp->signal();
-                    co_await runner->suspend();
+            jq.postCoro(jtCLIENT, "CoroTest", [&, id = i](auto const& c) {
+                a[id] = c;
+                g.signal();
+                c->yield();
 
-                    this->BEAST_EXPECT(**lvp == -1);
-                    **lvp = id;
-                    this->BEAST_EXPECT(**lvp == id);
-                    gp->signal();
-                    co_await runner->suspend();
+                this->BEAST_EXPECT(*lv == -1);
+                *lv = id;
+                this->BEAST_EXPECT(*lv == id);
+                g.signal();
+                c->yield();
 
-                    this->BEAST_EXPECT(**lvp == id);
-                    co_return;
-                });
+                this->BEAST_EXPECT(*lv == id);
+            });
             BEAST_EXPECT(g.wait_for(5s));
             a[i]->join();
         }

src/test/core/JobQueue_test.cpp

@@ -43,91 +43,87 @@ class JobQueue_test : public beast::unit_test::suite
         }
     }
 
-    // NOTE: All coroutine lambdas passed to postCoroTask use explicit
-    // pointer-by-value captures instead of [&] to work around a GCC 14
-    // bug where reference captures in coroutine lambdas are corrupted
-    // in the coroutine frame.
-
     void
-    testPostCoroTask()
+    testPostCoro()
     {
         jtx::Env env{*this};
 
         JobQueue& jQueue = env.app().getJobQueue();
         {
-            // Test repeated post()s until the coroutine completes.
+            // Test repeated post()s until the Coro completes.
             std::atomic<int> yieldCount{0};
-            auto const runner = jQueue.postCoroTask(
-                jtCLIENT, "PostCoroTest1", [ycp = &yieldCount](auto runner) -> CoroTask<void> {
-                    while (++(*ycp) < 4)
-                        co_await runner->suspend();
-                    co_return;
+            auto const coro = jQueue.postCoro(
+                jtCLIENT,
+                "PostCoroTest1",
+                [&yieldCount](std::shared_ptr<JobQueue::Coro> const& coroCopy) {
+                    while (++yieldCount < 4)
+                        coroCopy->yield();
                 });
-            BEAST_EXPECT(runner != nullptr);
+            BEAST_EXPECT(coro != nullptr);
 
             // Wait for the Job to run and yield.
             while (yieldCount == 0)
                 ;
 
-            // Now re-post until the CoroTaskRunner says it is done.
+            // Now re-post until the Coro says it is done.
             int old = yieldCount;
-            while (runner->runnable())
+            while (coro->runnable())
             {
-                BEAST_EXPECT(runner->post());
+                BEAST_EXPECT(coro->post());
                 while (old == yieldCount)
                 {
                 }
-                runner->join();
+                coro->join();
                 BEAST_EXPECT(++old == yieldCount);
             }
             BEAST_EXPECT(yieldCount == 4);
         }
         {
-            // Test repeated resume()s until the coroutine completes.
+            // Test repeated resume()s until the Coro completes.
             int yieldCount{0};
-            auto const runner = jQueue.postCoroTask(
-                jtCLIENT, "PostCoroTest2", [ycp = &yieldCount](auto runner) -> CoroTask<void> {
-                    while (++(*ycp) < 4)
-                        co_await runner->suspend();
-                    co_return;
+            auto const coro = jQueue.postCoro(
+                jtCLIENT,
+                "PostCoroTest2",
+                [&yieldCount](std::shared_ptr<JobQueue::Coro> const& coroCopy) {
+                    while (++yieldCount < 4)
+                        coroCopy->yield();
                 });
-            if (!runner)
+            if (!coro)
             {
-                // There's no good reason we should not get a runner, but we
+                // There's no good reason we should not get a Coro, but we
                 // can't continue without one.
                 BEAST_EXPECT(false);
                 return;
             }
 
             // Wait for the Job to run and yield.
-            runner->join();
+            coro->join();
 
-            // Now resume until the CoroTaskRunner says it is done.
+            // Now resume until the Coro says it is done.
             int old = yieldCount;
-            while (runner->runnable())
+            while (coro->runnable())
             {
-                runner->resume();  // Resume runs synchronously on this thread.
+                coro->resume();  // Resume runs synchronously on this thread.
                 BEAST_EXPECT(++old == yieldCount);
             }
             BEAST_EXPECT(yieldCount == 4);
         }
         {
             // If the JobQueue is stopped, we should no
-            // longer be able to post a coroutine (and calling postCoroTask()
-            // should return nullptr).
+            // longer be able to add a Coro (and calling postCoro() should
+            // return false).
             using namespace std::chrono_literals;
             jQueue.stop();
 
-            // The coroutine should never run, so having it access this
+            // The Coro should never run, so having the Coro access this
             // unprotected variable on the stack should be completely safe.
             // Not recommended for the faint of heart...
             bool unprotected;
-            auto const runner = jQueue.postCoroTask(
-                jtCLIENT, "PostCoroTest3", [up = &unprotected](auto) -> CoroTask<void> {
-                    *up = false;
-                    co_return;
+            auto const coro = jQueue.postCoro(
+                jtCLIENT, "PostCoroTest3", [&unprotected](std::shared_ptr<JobQueue::Coro> const&) {
+                    unprotected = false;
                 });
-            BEAST_EXPECT(runner == nullptr);
+            BEAST_EXPECT(coro == nullptr);
         }
     }
 
@@ -136,7 +132,7 @@ public:
     run() override
     {
         testAddJob();
-        testPostCoroTask();
+        testPostCoro();
     }
 };
 

src/test/jtx/impl/AMMTest.cpp

@@ -6,7 +6,6 @@
 
 #include <xrpld/rpc/RPCHandler.h>
 
-#include <xrpl/core/CoroTask.h>
 #include <xrpl/protocol/ApiVersion.h>
 #include <xrpl/protocol/STParsedJSON.h>
 #include <xrpl/resource/Fees.h>
@@ -194,6 +193,7 @@ AMMTest::find_paths_request(
          c,
          Role::USER,
          {},
+         {},
          RPC::apiVersionIfUnspecified},
         {},
         {}};
@@ -215,11 +215,11 @@ AMMTest::find_paths_request(
 
     Json::Value result;
     gate g;
-    app.getJobQueue().postCoroTask(jtCLIENT, "RPC-Client", [&](auto) -> CoroTask<void> {
+    app.getJobQueue().postCoro(jtCLIENT, "RPC-Client", [&](auto const& coro) {
         context.params = std::move(params);
+        context.coro = coro;
         RPC::doCommand(context, result);
         g.signal();
-        co_return;
     });
 
     using namespace std::chrono_literals;

src/xrpld/app/main/Application.cpp

@@ -1425,6 +1425,7 @@ ApplicationImp::setup(boost::program_options::variables_map const& cmdline)
              c,
              Role::ADMIN,
              {},
+             {},
              RPC::apiMaximumSupportedVersion},
             jvCommand};
 

src/xrpld/app/main/GRPCServer.cpp

@@ -3,7 +3,6 @@
 
 #include <xrpl/beast/core/CurrentThreadName.h>
 #include <xrpl/beast/net/IPAddressConversion.h>
-#include <xrpl/core/CoroTask.h>
 #include <xrpl/resource/Fees.h>
 
 namespace xrpl {
@@ -100,14 +99,13 @@ GRPCServerImpl::CallData<Request, Response>::process()
     // ensures that finished is always true when this CallData object
     // is returned as a tag in handleRpcs(), after sending the response
     finished_ = true;
-    auto runner = app_.getJobQueue().postCoroTask(
-        JobType::jtRPC, "gRPC-Client", [thisShared](auto) -> CoroTask<void> {
-            thisShared->processRequest();
-            co_return;
+    auto coro = app_.getJobQueue().postCoro(
+        JobType::jtRPC, "gRPC-Client", [thisShared](std::shared_ptr<JobQueue::Coro> coro) {
+            thisShared->process(coro);
         });
 
-    // If runner is null, then the JobQueue has already been shutdown
-    if (!runner)
+    // If coro is null, then the JobQueue has already been shutdown
+    if (!coro)
     {
         grpc::Status status{grpc::StatusCode::INTERNAL, "Job Queue is already stopped"};
         responder_.FinishWithError(status, this);
@@ -116,7 +114,7 @@ GRPCServerImpl::CallData<Request, Response>::process()
 
 template <class Request, class Response>
 void
-GRPCServerImpl::CallData<Request, Response>::processRequest()
+GRPCServerImpl::CallData<Request, Response>::process(std::shared_ptr<JobQueue::Coro> coro)
 {
     try
     {
@@ -158,6 +156,7 @@ GRPCServerImpl::CallData<Request, Response>::processRequest()
                  app_.getLedgerMaster(),
                  usage,
                  role,
+                 coro,
                  InfoSub::pointer(),
                  apiVersion},
                 request_};

src/xrpld/app/main/GRPCServer.h

@@ -206,12 +206,9 @@ private:
         clone() override;
 
     private:
-        /**
-         * Process the gRPC request. Called inside the CoroTask lambda
-         * posted to the JobQueue by process().
-         */
+        // process the request. Called inside the coroutine passed to JobQueue
         void
-        processRequest();
+        process(std::shared_ptr<JobQueue::Coro> coro);
 
         // return load type of this RPC
         Resource::Charge

src/xrpld/rpc/Context.h

@@ -3,6 +3,7 @@
 #include <xrpld/rpc/Role.h>
 
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/core/JobQueue.h>
 #include <xrpl/server/InfoSub.h>
 
 namespace xrpl {
@@ -23,6 +24,7 @@ struct Context
     LedgerMaster& ledgerMaster;
     Resource::Consumer& consumer;
     Role role;
+    std::shared_ptr<JobQueue::Coro> coro{};
     InfoSub::pointer infoSub{};
     unsigned int apiVersion;
 };

src/xrpld/rpc/ServerHandler.h

@@ -169,10 +169,13 @@ public:
 
 private:
     Json::Value
-    processSession(std::shared_ptr<WSSession> const& session, Json::Value const& jv);
+    processSession(
+        std::shared_ptr<WSSession> const& session,
+        std::shared_ptr<JobQueue::Coro> const& coro,
+        Json::Value const& jv);
 
     void
-    processSession(std::shared_ptr<Session> const&);
+    processSession(std::shared_ptr<Session> const&, std::shared_ptr<JobQueue::Coro> coro);
 
     void
     processRequest(
@@ -180,6 +183,7 @@ private:
         std::string const& request,
         beast::IP::Endpoint const& remoteIPAddress,
         Output&&,
+        std::shared_ptr<JobQueue::Coro> coro,
         std::string_view forwardedFor,
         std::string_view user);
 

src/xrpld/rpc/detail/ServerHandler.cpp

@@ -14,7 +14,6 @@
 #include <xrpl/basics/make_SSLContext.h>
 #include <xrpl/beast/net/IPAddressConversion.h>
 #include <xrpl/beast/rfc2616.h>
-#include <xrpl/core/CoroTask.h>
 #include <xrpl/core/JobQueue.h>
 #include <xrpl/json/json_reader.h>
 #include <xrpl/json/to_string.h>
@@ -285,10 +284,9 @@ ServerHandler::onRequest(Session& session)
     }
 
     std::shared_ptr<Session> detachedSession = session.detach();
-    auto const postResult = m_jobQueue.postCoroTask(
-        jtCLIENT_RPC, "RPC-Client", [this, detachedSession](auto) -> CoroTask<void> {
-            processSession(detachedSession);
-            co_return;
+    auto const postResult = m_jobQueue.postCoro(
+        jtCLIENT_RPC, "RPC-Client", [this, detachedSession](std::shared_ptr<JobQueue::Coro> coro) {
+            processSession(detachedSession, coro);
         });
     if (postResult == nullptr)
     {
@@ -324,18 +322,17 @@ ServerHandler::onWSMessage(
 
     JLOG(m_journal.trace()) << "Websocket received '" << jv << "'";
 
-    auto const postResult = m_jobQueue.postCoroTask(
+    auto const postResult = m_jobQueue.postCoro(
         jtCLIENT_WEBSOCKET,
         "WS-Client",
-        [this, session, jv = std::move(jv)](auto) -> CoroTask<void> {
-            auto const jr = this->processSession(session, jv);
+        [this, session, jv = std::move(jv)](std::shared_ptr<JobQueue::Coro> const& coro) {
+            auto const jr = this->processSession(session, coro, jv);
             auto const s = to_string(jr);
             auto const n = s.length();
             boost::beast::multi_buffer sb(n);
             sb.commit(boost::asio::buffer_copy(sb.prepare(n), boost::asio::buffer(s.c_str(), n)));
             session->send(std::make_shared<StreambufWSMsg<decltype(sb)>>(std::move(sb)));
             session->complete();
-            co_return;
         });
     if (postResult == nullptr)
     {
@@ -376,7 +373,10 @@ logDuration(Json::Value const& request, T const& duration, beast::Journal& journ
 }
 
 Json::Value
-ServerHandler::processSession(std::shared_ptr<WSSession> const& session, Json::Value const& jv)
+ServerHandler::processSession(
+    std::shared_ptr<WSSession> const& session,
+    std::shared_ptr<JobQueue::Coro> const& coro,
+    Json::Value const& jv)
 {
     auto is = std::static_pointer_cast<WSInfoSub>(session->appDefined);
     if (is->getConsumer().disconnect(m_journal))
@@ -443,6 +443,7 @@ ServerHandler::processSession(std::shared_ptr<WSSession> const& session, Json::V
                  app_.getLedgerMaster(),
                  is->getConsumer(),
                  role,
+                 coro,
                  is,
                  apiVersion},
                 jv,
@@ -513,14 +514,18 @@ ServerHandler::processSession(std::shared_ptr<WSSession> const& session, Json::V
     return jr;
 }
 
+// Run as a coroutine.
 void
-ServerHandler::processSession(std::shared_ptr<Session> const& session)
+ServerHandler::processSession(
+    std::shared_ptr<Session> const& session,
+    std::shared_ptr<JobQueue::Coro> coro)
 {
     processRequest(
         session->port(),
         buffers_to_string(session->request().body().data()),
         session->remoteAddress().at_port(0),
         makeOutput(*session),
+        coro,
         forwardedFor(session->request()),
         [&] {
             auto const iter = session->request().find("X-User");
@@ -557,6 +562,7 @@ ServerHandler::processRequest(
     std::string const& request,
     beast::IP::Endpoint const& remoteIPAddress,
     Output&& output,
+    std::shared_ptr<JobQueue::Coro> coro,
     std::string_view forwardedFor,
     std::string_view user)
 {
@@ -813,6 +819,7 @@ ServerHandler::processRequest(
              app_.getLedgerMaster(),
              usage,
              role,
+             coro,
              InfoSub::pointer(),
              apiVersion},
             params,

src/xrpld/rpc/handlers/RipplePathFind.cpp

@@ -7,9 +7,6 @@
 #include <xrpl/protocol/RPCErr.h>
 #include <xrpl/resource/Fees.h>
 
-#include <condition_variable>
-#include <mutex>
-
 namespace xrpl {
 
 // This interface is deprecated.
@@ -40,31 +37,98 @@ doRipplePathFind(RPC::JsonContext& context)
         PathRequest::pointer request;
         lpLedger = context.ledgerMaster.getClosedLedger();
 
-        // makeLegacyPathRequest enqueues a path-finding job that runs
-        // asynchronously.  We block this thread with a condition_variable
-        // until the path-finding continuation signals completion.
-        // If makeLegacyPathRequest cannot schedule the job (e.g. during
-        // shutdown), it returns an empty request and we skip the wait.
-        std::mutex mtx;
-        std::condition_variable cv;
-        bool pathDone = false;
-
+        // It doesn't look like there's much odd happening here, but you should
+        // be aware this code runs in a JobQueue::Coro, which is a coroutine.
+        // And we may be flipping around between threads.  Here's an overview:
+        //
+        // 1. We're running doRipplePathFind() due to a call to
+        //    ripple_path_find.  doRipplePathFind() is currently running
+        //    inside of a JobQueue::Coro using a JobQueue thread.
+        //
+        // 2. doRipplePathFind's call to makeLegacyPathRequest() enqueues the
+        //    path-finding request.  That request will (probably) run at some
+        //    indeterminate future time on a (probably different) JobQueue
+        //    thread.
+        //
+        // 3. As a continuation from that path-finding JobQueue thread, the
+        //    coroutine we're currently running in (!) is posted to the
+        //    JobQueue.  Because it is a continuation, that post won't
+        //    happen until the path-finding request completes.
+        //
+        // 4. Once the continuation is enqueued, and we have reason to think
+        //    the path-finding job is likely to run, then the coroutine we're
+        //    running in yield()s.  That means it surrenders its thread in
+        //    the JobQueue.  The coroutine is suspended, but ready to run,
+        //    because it is kept resident by a shared_ptr in the
+        //    path-finding continuation.
+        //
+        // 5. If all goes well then path-finding runs on a JobQueue thread
+        //    and executes its continuation.  The continuation posts this
+        //    same coroutine (!) to the JobQueue.
+        //
+        // 6. When the JobQueue calls this coroutine, this coroutine resumes
+        //    from the line below the coro->yield() and returns the
+        //    path-finding result.
+        //
+        // With so many moving parts, what could go wrong?
+        //
+        // Just in terms of the JobQueue refusing to add jobs at shutdown
+        // there are two specific things that can go wrong.
+        //
+        // 1. The path-finding Job queued by makeLegacyPathRequest() might be
+        //    rejected (because we're shutting down).
+        //
+        //    Fortunately this problem can be addressed by looking at the
+        //    return value of makeLegacyPathRequest().  If
+        //    makeLegacyPathRequest() cannot get a thread to run the path-find
+        //    on, then it returns an empty request.
+        //
+        // 2. The path-finding job might run, but the Coro::post() might be
+        //    rejected by the JobQueue (because we're shutting down).
+        //
+        //    We handle this case by resuming (not posting) the Coro.
+        //    By resuming the Coro, we allow the Coro to run to completion
+        //    on the current thread instead of requiring that it run on a
+        //    new thread from the JobQueue.
+        //
+        // Both of these failure modes are hard to recreate in a unit test
+        // because they are so dependent on inter-thread timing.  However
+        // the failure modes can be observed by synchronously (inside the
+        // rippled source code) shutting down the application.  The code to
+        // do so looks like this:
+        //
+        //   context.app.signalStop();
+        //   while (! context.app.getJobQueue().jobCounter().joined()) { }
+        //
+        // The first line starts the process of shutting down the app.
+        // The second line waits until no more jobs can be added to the
+        // JobQueue before letting the thread continue.
+        //
+        // May 2017
         jvResult = context.app.getPathRequests().makeLegacyPathRequest(
             request,
-            [&]() {
+            [&context]() {
+                // Copying the shared_ptr keeps the coroutine alive up
+                // through the return.  Otherwise the storage under the
+                // captured reference could evaporate when we return from
+                // coroCopy->resume().  This is not strictly necessary, but
+                // will make maintenance easier.
+                std::shared_ptr<JobQueue::Coro> coroCopy{context.coro};
+                if (!coroCopy->post())
                 {
-                    std::lock_guard lk(mtx);
-                    pathDone = true;
+                    // The post() failed, so we won't get a thread to let
+                    // the Coro finish.  We'll call Coro::resume() so the
+                    // Coro can finish on our thread.  Otherwise the
+                    // application will hang on shutdown.
+                    coroCopy->resume();
                 }
-                cv.notify_one();
             },
             context.consumer,
             lpLedger,
             context.params);
         if (request)
         {
-            std::unique_lock lk(mtx);
-            cv.wait(lk, [&] { return pathDone; });
+            context.coro->yield();
             jvResult = request->doStatus(context.params);
         }