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refactor(telemetry): split SpanGuard into unscoped SpanGuard + scoped ScopedSpanGuard

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Separate the two responsibilities the old SpanGuard fused: span ownership
(thread-free) and scope activation (thread-bound TLS push).

- SpanGuard now owns ONLY the span. Its Impl drops the optional<Scope>,
  the owner thread-id, the Detached tag and the scope-less ctor; ~Impl is
  just `if (span) span->End()`. The guard never binds a thread-local
  context stack, so it may be moved to and destroyed on any thread.
- ScopedSpanGuard is a new pimpl type that wraps a SpanGuard plus an
  optional<Scope>. Member order (guard first, scope second) pops the
  scope before the span ends. It is non-copyable and non-movable;
  factories return unnamed temporaries so guaranteed copy elision covers
  `auto s = ScopedSpanGuard::freshRoot(...)`.
- `operator SpanGuard() &&` replaces detached()/detachInPlace(): it pops
  the scope eagerly on the origin thread and yields a thread-free
  SpanGuard for handoff to a job or another thread. detached(),
  detachInPlace() (both overloads) and the Detached apparatus are deleted.
- Move-assignment is re-enabled on SpanGuard (no Scope to re-bind), in
  both the real class and the no-op stub.
- rootSpan() renamed to freshRoot() in both classes (behavior unchanged:
  still forces kIsRootSpanKey).
- hashSpan behavior is intentionally unchanged (only builds the now
  unscoped Impl); the true-root IdGenerator fix is a separate later task.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Pratik Mankawde
2026-07-21 18:03:20 +01:00
parent f9b2d725a0
commit 508c91d36c
2 changed files with 639 additions and 220 deletions
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545
include/xrpl/telemetry/SpanGuard.h
View File

@@ -1,25 +1,38 @@
#pragma once
/**
* RAII guard for OpenTelemetry trace spans.
* RAII guards for OpenTelemetry trace spans.
*
* Wraps an OTel Span and Scope behind the pimpl idiom so that no
* opentelemetry headers are exposed in this public header. When
* XRPL_ENABLE_TELEMETRY is not defined, SpanGuard is an empty class
* with all-inline no-op methods — zero overhead, zero dependencies.
* This header declares two complementary span guards, split by
* responsibility:
*
* Dependency diagram:
* - SpanGuard — owns a span only. Thread-free: it never touches the
* OTel thread-local context stack, so it may be moved
* to and destroyed on any thread. Movable AND
* move-assignable.
* - ScopedSpanGuard — owns a SpanGuard plus an active OTel Scope that
* pushes the span onto the constructing thread's
* context stack. Thread-bound: it must be created and
* destroyed on the same thread. Non-copyable and
* non-movable.
*
* Both wrap all OpenTelemetry types behind the pimpl idiom so no
* opentelemetry headers are exposed here. When XRPL_ENABLE_TELEMETRY
* is not defined, both are empty classes with all-inline no-op methods
* — zero overhead, zero dependencies.
*
* SpanGuard dependency diagram:
*
* +--------------------------------------------+
* | SpanGuard |
* | (unscoped, thread-free) |
* +--------------------------------------------+
* | - impl_ : unique_ptr<Impl> (pimpl) |
* +--------------------------------------------+
* | + span(cat, prefix, name) [static] |
* | + rootSpan(cat, prefix, name) [static] |
* | + freshRoot(cat, prefix, name) [static] |
* | + childSpan(name) : SpanGuard |
* | + linkedSpan(name) : SpanGuard |
* | + detached() : SpanGuard |
* | + captureContext() : SpanContext |
* | + setAttribute(key, value) |
* | + setOk() / setError(desc) |
@@ -29,14 +42,10 @@
* | + operator bool() |
* +--------------------------------------------+
* | hides (pimpl)
* +-------+-------------+
* | |
* +--------+ +---------------------------+
* | Span | | optional<Scope> |
* | (OTel) | | (OTel, non-movable) |
* | | | present : scoped guard |
* | | | nullopt : detached guard |
* +--------+ +---------------------------+
* +--------+
* | Span |
* | (OTel) |
* +--------+
*
* Static factory methods access the global Telemetry instance
* internally (via Telemetry::getInstance()), check whether tracing
@@ -60,7 +69,7 @@
* TraceCategory::Rpc, rpc_span::prefix::command, commandName);
* span.setAttribute(rpc_span::attr::command, commandName);
* span.setAttribute(rpc_span::attr::rpcStatus, rpc_span::val::success);
* // span ended automatically on scope exit
* // span ended automatically when the guard is destroyed
* @endcode
*
* 2. Error recording:
@@ -110,7 +119,7 @@
* }
* @endcode
*
* 6. Fresh trace root at an inbound entry point (primary rootSpan use):
* 6. Fresh trace root at an inbound entry point (primary freshRoot use):
* @code
* #include <xrpld/overlay/detail/PeerSpanNames.h>
* using namespace xrpl::telemetry;
@@ -119,56 +128,50 @@
* // already have unrelated spans active — start a clean root so
* // those do not become parents of this trace. Names come from a
* // *SpanNames.h header, never raw literals.
* auto span = SpanGuard::rootSpan(
* auto span = SpanGuard::freshRoot(
* TraceCategory::Peer, seg::peer, peer_span::op::validationReceive);
* span.setAttribute(peer_span::attr::ledgerHash, hashStr);
* @endcode
*
* 7. Hand a span to a job on another thread (edge case, detached):
* 7. Hand a span to a job on another thread (thread-free — just move):
* @code
* #include <xrpld/app/ledger/detail/LedgerSpanNames.h>
* using namespace xrpl::telemetry;
*
* // Build the guard on THIS thread, then strip its thread-local
* // Scope so it can be safely moved into a job and ended there.
* // SpanGuard owns no thread-local Scope, so it is safe to move
* // into a job and end on the worker thread. No detach step is
* // needed — just move the guard in.
* auto span = SpanGuard::span(
* TraceCategory::Ledger, seg::ledger, ledger_span::op::build);
* jobQueue.addJob(
* [g = std::move(span).detached()]() mutable {
* [g = std::move(span)]() mutable {
* doWork();
* // g's span ends when the job's lambda is destroyed,
* // on the worker thread — no origin-stack corruption.
* // on the worker thread.
* });
* @endcode
*
* @note Thread safety: A SCOPED guard (from span(), rootSpan(),
* childSpan(), linkedSpan()) must only be used on the thread where it
* was constructed — its internal Scope binds to that thread's
* thread-local context stack, and destroying it elsewhere would pop
* the wrong stack. A guard returned by detached() holds no Scope, so
* it may be moved to and destroyed on another thread; detached()
* itself must be called on the origin (constructing) thread. Use
* captureContext() to propagate the trace context to other threads.
* Violating this rule is enforced (not just documented): a scoped
* guard destroyed on a foreign thread, or detached() called from one,
* trips an XRPL_ASSERT in debug/test/fuzzing builds instead of
* silently corrupting the other thread's context stack.
* @note Thread safety: SpanGuard is thread-free. It holds only the
* span (no Scope), so it never binds to a thread-local context stack
* and may be moved to and destroyed on any thread. To make a span the
* ambient parent for child spans on a thread, wrap it in a
* ScopedSpanGuard. Use captureContext() to propagate the trace
* context across threads explicitly.
*
* @note Move semantics: Move construction transfers ownership of
* the pimpl pointer — no double-Scope issues. Move assignment is
* deleted to prevent re-scoping mid-flight.
* @note Move semantics: Move construction and move assignment both
* transfer ownership of the pimpl pointer. There is no Scope to
* re-bind, so move assignment is safe and enabled. Copy is deleted.
*
* @note Known limitations:
* - Attributes cannot be removed per the OTel spec; use
* setAttribute with an empty value as a convention.
* - SpanGuard::span() (raw Span access) is intentionally not
* exposed — all interaction goes through the public methods.
* - The raw OTel Span is intentionally not exposed — all interaction
* goes through the public methods.
*/
#include <cstdint>
#include <exception>
#include <memory>
#include <optional>
#include <string_view>
namespace xrpl::telemetry {
@@ -225,9 +228,16 @@ public:
#ifdef XRPL_ENABLE_TELEMETRY
/**
* RAII wrapper that activates a span on construction and ends it on
* destruction. All OTel types are hidden behind the Impl pointer.
* Non-copyable, move-constructible.
* RAII owner of an OTel span (unscoped, thread-free).
*
* Holds only the span behind the Impl pointer — it never pushes the
* span onto the thread-local context stack, so it carries no
* thread-affinity and may be moved to and destroyed on any thread.
* The span is ended when the guard is destroyed (unless discard()
* ended it earlier). Non-copyable; movable and move-assignable.
*
* To activate a span as the ambient parent for child spans on a
* thread, wrap the guard in a ScopedSpanGuard.
*/
class SpanGuard
{
@@ -236,6 +246,10 @@ class SpanGuard
explicit SpanGuard(std::unique_ptr<Impl> impl);
// ScopedSpanGuard wraps a SpanGuard and needs the raw span to build
// its Scope; it reads impl_ directly so no OTel type leaks here.
friend class ScopedSpanGuard;
public:
/**
* Construct a null (no-op) guard. All methods are safe to call.
@@ -245,7 +259,7 @@ public:
SpanGuard(SpanGuard&& other) noexcept;
SpanGuard&
operator=(SpanGuard&&) = delete;
operator=(SpanGuard&&) noexcept;
SpanGuard(SpanGuard const&) = delete;
SpanGuard&
operator=(SpanGuard const&) = delete;
@@ -277,16 +291,17 @@ public:
* @param prefix Span name prefix (e.g. "peer").
* @param name Span name suffix (e.g. "validation.receive").
* @return An active root-span guard, or a null guard if disabled.
* @note Must be called on the thread that will own the span, like
* span(); the returned guard is scoped to that thread.
*/
[[nodiscard]] static SpanGuard
rootSpan(TraceCategory cat, std::string_view prefix, std::string_view name);
freshRoot(TraceCategory cat, std::string_view prefix, std::string_view name);
// --- Child / linked span creation ----------------------------------
/**
* Create a child span parented to this guard's active context.
* Create a child span parented to the current thread's active
* context. This is meaningful when this guard's span is active on
* the thread (e.g. wrapped in a ScopedSpanGuard); otherwise the
* child inherits whatever context is currently on the stack.
* @param name Span name for the child.
* @return A new guard, or null if this guard is inactive.
*/
@@ -321,30 +336,6 @@ public:
[[nodiscard]] static SpanGuard
linkedSpan(std::string_view name, SpanContext const& linkCtx);
/**
* Detach this guard's span from the current thread's context stack.
*
* A scoped guard holds an OTel Scope bound to the constructing
* thread's context stack. Moving such a guard to another thread
* (e.g. into a job queue) and destroying it there would pop the
* wrong stack, leaving the origin thread's stack corrupted so
* later spans inherit a stale parent. detached() pops the Scope
* now, on the origin thread, and returns a new guard that holds
* the same span with no thread-local binding.
*
* Consumes this guard (rvalue-qualified): after the call this
* guard is null and the returned guard owns the span.
*
* @return A scope-less guard safe to move to and destroy on
* another thread, or a null guard if this guard was null.
* @note Must be called on the origin (constructing) thread; this is
* checked by an XRPL_ASSERT in debug/test/fuzzing builds. The
* returned guard may be freely moved across threads; only
* its final destruction ends the span.
*/
[[nodiscard]] SpanGuard
detached() &&;
// --- Context capture -----------------------------------------------
/**
@@ -432,42 +423,260 @@ public:
operator bool() const;
};
// --- Detach-in-place helpers -----------------------------------------------
/**
* Detach an active `std::optional<SpanGuard>` member in place.
* RAII guard that activates a span on the current thread (scoped).
*
* Equivalent to `guard.emplace(std::move(*guard).detached())`, which is the
* required idiom for detaching a live guard stored in an `optional` (move
* assignment is deleted because the underlying Scope cannot be re-scoped in
* place). No-op if `guard` is empty or already null.
* Wraps a SpanGuard (which owns the span) plus an OTel Scope that
* pushes the span onto this thread's thread-local context stack for
* the guard's lifetime, so child spans created on the thread inherit
* it as parent. On destruction the Scope pops BEFORE the span ends
* (member order: guard first, scope second). Non-copyable and
* non-movable — factories return unnamed temporaries, so guaranteed
* copy elision (C++17) covers `auto s = ScopedSpanGuard::freshRoot(...)`.
*
* @param guard The optional guard to detach. Must be called on the thread
* that constructed the active guard inside it (same rule as
* `SpanGuard::detached()`).
* @note Must run BEFORE any `captureContext()` snapshot is taken if the
* caller also needs the pre-detach context — capture first, then call
* this helper (same ordering rule `detached()` itself has).
* When the span must outlive the current thread (e.g. handed to a job
* queue), convert to a plain SpanGuard with `operator SpanGuard() &&`:
* that pops the Scope eagerly on the origin thread and yields a
* thread-free guard.
*
* ScopedSpanGuard dependency diagram:
*
* +--------------------------------------------+
* | ScopedSpanGuard |
* | (scoped, thread-bound) |
* +--------------------------------------------+
* | - impl_ : unique_ptr<ScopedImpl> (pimpl) |
* +--------------------------------------------+
* | + (cat, prefix, name) [ctor] |
* | + freshRoot(cat, prefix, name) [static] |
* | + childSpan(name) : ScopedSpanGuard |
* | + linkedSpan(name) : ScopedSpanGuard |
* | + operator SpanGuard() && (handoff) |
* | + setAttribute / setOk / setError / ... |
* | + captureContext() / discard() |
* | + operator bool() |
* +--------------------------------------------+
* | hides (pimpl)
* +------+--------------------+
* | |
* +----------+ +-----------------------------+
* | SpanGuard| | optional<Scope> |
* | (span) | | (OTel, thread-bound; |
* | | | present : span active) |
* +----------+ +-----------------------------+
*
* Usage examples:
*
* 1. Same-thread scoped tracing (child inherits parent automatically):
* @code
* using namespace xrpl::telemetry;
*
* ScopedSpanGuard span(
* TraceCategory::Rpc, rpc_span::prefix::command, commandName);
* span.setAttribute(rpc_span::attr::command, commandName);
* // childSpan parents to `span` because it is active on this thread
* auto child = span.childSpan(rpc_span::op::dispatch);
* @endcode
*
* 2. Capture on this thread, hand off to another (edge case):
* @code
* using namespace xrpl::telemetry;
*
* auto scoped = ScopedSpanGuard::freshRoot(
* TraceCategory::Ledger, seg::ledger, ledger_span::op::build);
* // Pop the scope now, on this thread, and move a thread-free
* // SpanGuard into the job.
* SpanGuard span = std::move(scoped);
* jobQueue.addJob([g = std::move(span)]() mutable { doWork(); });
* @endcode
*
* @note Thread safety: A ScopedSpanGuard must be constructed AND
* destroyed on the same thread — its Scope binds to that thread's
* context stack. `operator SpanGuard() &&` and the destructor must
* both run on the owning thread; both check this with an XRPL_ASSERT
* in debug/test/fuzzing builds. `operator SpanGuard() &&` pops the
* scope eagerly, so the resulting SpanGuard is thread-free.
*
* @note Known limitations:
* - Non-movable: cannot be stored in a container that relocates, and
* cannot be returned then move-assigned into an existing variable.
* Store the thread-free SpanGuard (via `operator SpanGuard() &&`)
* instead when a movable handle is needed.
* - Same attribute-removal limitation as SpanGuard.
*/
void
detachInPlace(std::optional<SpanGuard>& guard);
class ScopedSpanGuard
{
struct ScopedImpl;
std::unique_ptr<ScopedImpl> impl_;
/**
* Detach an active `std::shared_ptr<SpanGuard>`, returning the detached
* guard as a new `shared_ptr`.
*
* Equivalent to
* `guard = std::make_shared<SpanGuard>(std::move(*guard).detached())`.
* No-op (returns the input unchanged) if `guard` is null or points at a
* null guard.
*
* @param guard The guard to detach, taken by value (the caller's pointer
* is consumed; assign the return value back).
* @return A `shared_ptr` to the detached guard (new allocation), or the
* input pointer unchanged if it was null/inactive.
*/
[[nodiscard]] std::shared_ptr<SpanGuard>
detachInPlace(std::shared_ptr<SpanGuard> guard);
explicit ScopedSpanGuard(SpanGuard&& guard);
public:
/**
* Create a scoped span guarded by a TraceCategory flag and activate
* it on this thread. Equivalent to SpanGuard::span() wrapped in an
* active Scope. The span name is built as "prefix.name".
* @param cat Trace subsystem category.
* @param prefix Span name prefix (e.g. "rpc.command").
* @param name Span name suffix (e.g. "submit").
*/
ScopedSpanGuard(TraceCategory cat, std::string_view prefix, std::string_view name);
~ScopedSpanGuard();
ScopedSpanGuard(ScopedSpanGuard&&) = delete;
ScopedSpanGuard&
operator=(ScopedSpanGuard&&) = delete;
ScopedSpanGuard(ScopedSpanGuard const&) = delete;
ScopedSpanGuard&
operator=(ScopedSpanGuard const&) = delete;
// --- Static factory methods ----------------------------------------
/**
* Create a scoped span that always starts a fresh trace root and
* activate it on this thread. See SpanGuard::freshRoot().
* @param cat Trace subsystem category.
* @param prefix Span name prefix.
* @param name Span name suffix.
* @return An active scoped root-span guard, or a null one if disabled.
*/
[[nodiscard]] static ScopedSpanGuard
freshRoot(TraceCategory cat, std::string_view prefix, std::string_view name);
// --- Child / linked span creation ----------------------------------
/**
* Create a scoped child span parented to this guard's active span
* and activate it on this thread.
* @param name Span name for the child.
* @return A new scoped guard, or a null one if this guard is inactive.
*/
[[nodiscard]] ScopedSpanGuard
childSpan(std::string_view name) const;
/**
* Create a scoped child span parented to an explicit captured
* context and activate it on this thread.
* @param name Span name for the child.
* @param parentCtx Context captured via captureContext().
* @return A new scoped guard, or a null one if parentCtx is invalid.
*/
[[nodiscard]] static ScopedSpanGuard
childSpan(std::string_view name, SpanContext const& parentCtx);
/**
* Create a scoped span linked (follows-from) to this guard's span
* and activate it on this thread.
* @param name Span name for the linked span.
* @return A new scoped guard, or a null one if this guard is inactive.
*/
[[nodiscard]] ScopedSpanGuard
linkedSpan(std::string_view name) const;
/**
* Create a scoped span linked to an explicit captured context and
* activate it on this thread.
* @param name Span name for the linked span.
* @param linkCtx Context to link from.
* @return A new scoped guard, or a null one if linkCtx is invalid.
*/
[[nodiscard]] static ScopedSpanGuard
linkedSpan(std::string_view name, SpanContext const& linkCtx);
// --- Handoff bridge -------------------------------------------------
/**
* Pop the active Scope on the origin thread and yield the span as a
* thread-free SpanGuard. Use to move a span into a job or onto
* another thread. Must be called on the constructing thread.
* @return The unscoped SpanGuard that now owns the span.
*/
operator SpanGuard() &&;
// --- Context capture -----------------------------------------------
/**
* Snapshot the current thread's OTel context for cross-thread use.
* @return An opaque SpanContext, or an invalid one if null guard.
*/
[[nodiscard]] SpanContext
captureContext() const;
// --- Forwarding methods (delegate to the owned SpanGuard) ----------
/**
* Set a string attribute. No-op on a null guard.
*/
void
setAttribute(std::string_view key, std::string_view value);
/**
* Set a string attribute (C-string overload). No-op on a null guard.
*/
void
setAttribute(std::string_view key, char const* value);
/**
* Set an integer attribute. No-op on a null guard.
*/
void
setAttribute(std::string_view key, std::int64_t value);
/**
* Set a floating-point attribute. No-op on a null guard.
*/
void
setAttribute(std::string_view key, double value);
/**
* Set a boolean attribute. No-op on a null guard.
*/
void
setAttribute(std::string_view key, bool value);
/**
* Mark the span status as OK. No-op on a null guard.
*/
void
setOk();
/**
* Mark the span status as error. No-op on a null guard.
* @param description Optional human-readable error description.
*/
void
setError(std::string_view description = "");
/**
* Add a named event to the span's timeline. No-op on a null guard.
* @param name Event name.
*/
void
addEvent(std::string_view name);
/**
* Record an exception as a span event and mark status as error.
* No-op on a null guard.
* @param e The exception to record.
*/
void
recordException(std::exception const& e);
/**
* Mark this span for discard and end it immediately. discard() pops the
* thread-local scope right away (on the owning thread) and discards the
* span. After discard() the guard is inert and its destructor is a no-op.
*/
void
discard();
/**
* @return true if this guard holds an active span.
*/
explicit
operator bool() const;
};
// ---------------------------------------------------------------------------
// No-op stub (all inline, zero overhead, no OTel dependency)
@@ -481,7 +690,7 @@ public:
~SpanGuard() = default;
SpanGuard(SpanGuard&&) noexcept = default;
SpanGuard&
operator=(SpanGuard&&) = delete;
operator=(SpanGuard&&) noexcept = default;
SpanGuard(SpanGuard const&) = delete;
SpanGuard&
operator=(SpanGuard const&) = delete;
@@ -493,7 +702,7 @@ public:
}
[[nodiscard]] static SpanGuard
rootSpan(TraceCategory, std::string_view, std::string_view)
freshRoot(TraceCategory, std::string_view, std::string_view)
{
return {};
}
@@ -520,12 +729,6 @@ public:
return {};
}
[[nodiscard]] SpanGuard
detached() &&
{
return {};
}
[[nodiscard]] SpanContext
captureContext() const
{
@@ -582,18 +785,114 @@ public:
}
};
// --- Detach-in-place helpers (no-op stubs) ---------------------------------
inline void
detachInPlace(std::optional<SpanGuard>&)
class ScopedSpanGuard
{
}
// Private default ctor lets the inline factories/child methods build
// a no-op instance without exposing a public default constructor
// (mirrors the real class, which has no public default ctor).
ScopedSpanGuard() = default;
[[nodiscard]] inline std::shared_ptr<SpanGuard>
detachInPlace(std::shared_ptr<SpanGuard> guard)
{
return guard;
}
public:
ScopedSpanGuard(TraceCategory, std::string_view, std::string_view)
{
}
~ScopedSpanGuard() = default;
ScopedSpanGuard(ScopedSpanGuard&&) = delete;
ScopedSpanGuard&
operator=(ScopedSpanGuard&&) = delete;
ScopedSpanGuard(ScopedSpanGuard const&) = delete;
ScopedSpanGuard&
operator=(ScopedSpanGuard const&) = delete;
[[nodiscard]] static ScopedSpanGuard
freshRoot(TraceCategory, std::string_view, std::string_view)
{
return {};
}
// NOLINTBEGIN(readability-convert-member-functions-to-static)
[[nodiscard]] ScopedSpanGuard
childSpan(std::string_view) const
{
return {};
}
[[nodiscard]] static ScopedSpanGuard
childSpan(std::string_view, SpanContext const&)
{
return {};
}
[[nodiscard]] ScopedSpanGuard
linkedSpan(std::string_view) const
{
return {};
}
[[nodiscard]] static ScopedSpanGuard
linkedSpan(std::string_view, SpanContext const&)
{
return {};
}
[[nodiscard]] SpanContext
captureContext() const
{
return {};
}
// NOLINTEND(readability-convert-member-functions-to-static)
operator SpanGuard() &&
{
return {};
}
void
setAttribute(std::string_view, std::string_view)
{
}
void
setAttribute(std::string_view, char const*)
{
}
void
setAttribute(std::string_view, std::int64_t)
{
}
void
setAttribute(std::string_view, double)
{
}
void
setAttribute(std::string_view, bool)
{
}
void
setOk()
{
}
void
setError(std::string_view = "")
{
}
void
addEvent(std::string_view)
{
}
void
recordException(std::exception const&)
{
}
void
discard()
{
}
explicit
operator bool() const
{
return false;
}
};
#endif // XRPL_ENABLE_TELEMETRY

314
src/libxrpl/telemetry/SpanGuard.cpp
View File

@@ -1,23 +1,26 @@
/**
* Pimpl implementation for SpanGuard and SpanContext.
* Pimpl implementation for SpanGuard, ScopedSpanGuard and SpanContext.
*
* All OpenTelemetry SDK types are confined to this translation unit.
* The public SpanGuard.h header contains only standard-library types
* and forward-declares the Impl struct.
* and forward-declares the Impl / ScopedImpl structs.
*
* Two guards with split responsibilities live here:
* - SpanGuard::Impl holds ONLY the OTel Span (shared_ptr). It never
* touches the thread-local context stack, so a SpanGuard is
* thread-free and may be moved to and destroyed on any thread.
* - ScopedSpanGuard::ScopedImpl holds a SpanGuard plus an optional
* Scope. The Scope pushes the span onto the constructing thread's
* context stack; member order (guard first, scope second) ensures
* the Scope pops BEFORE the span ends on destruction. It is
* thread-bound: construct and destroy on the same thread.
*
* Static factory methods access the global Telemetry instance via
* Telemetry::getInstance(), check whether the requested TraceCategory
* is enabled, and return either an active guard with a real Span+Scope
* or a null guard whose methods are all no-ops.
* is enabled, and return either an active guard with a real Span or a
* null guard whose methods are all no-ops.
*
* The Impl struct holds the OTel Span (shared_ptr) and an optional
* Scope. Scope is non-movable, but since Impl lives behind a
* unique_ptr, SpanGuard's move constructor simply transfers the
* pointer — no double-Scope issues. A scoped guard holds the Scope;
* detached() produces an Impl with no Scope (nullopt) so the guard
* carries no thread-local binding and is safe to move across threads.
*
* @see SpanGuard (SpanGuard.h), Telemetry (Telemetry.h),
* @see SpanGuard, ScopedSpanGuard (SpanGuard.h), Telemetry (Telemetry.h),
* FilteringSpanProcessor (Telemetry.cpp)
*/
@@ -79,65 +82,22 @@ SpanContext::isValid() const
struct SpanGuard::Impl
{
/**
* The OTel span being guarded. Set to nullptr after discard() or
* once detached() moves it into a new guard, so ~Impl skips End().
* The OTel span being guarded. Set to nullptr after discard() so
* ~Impl skips End().
*/
opentelemetry::nostd::shared_ptr<otel_trace::Span> span;
/**
* Scope that activates span on the current thread's context stack.
* nullopt for a detached guard, which holds the span with no
* thread-local binding and is therefore safe to move across threads.
*/
std::optional<otel_trace::Scope> scope;
/**
* Thread that constructed this Impl. Meaningful only when `scope`
* holds a value: a Scope is bound to the thread-local context stack
* of the thread that pushed it, so popping it (via ~Scope, when
* ~Impl runs) on a different thread corrupts that thread's stack.
* Checked in ~Impl() and detached() to turn a silent cross-thread
* corruption into an assertion failure in debug/test/fuzzing builds.
*/
std::thread::id owner{std::this_thread::get_id()};
/**
* Construct a scoped guard: the span is pushed onto this thread's
* active-context stack for the lifetime of the guard.
* Construct an unscoped guard: the span is owned but NOT pushed
* onto any thread's context stack. The guard is thread-free.
* @param s The span to guard.
*/
explicit Impl(opentelemetry::nostd::shared_ptr<otel_trace::Span> s) : span(std::move(s))
{
scope.emplace(span);
}
/**
* Tag type selecting the scope-less (detached) constructor.
*/
struct Detached
{
};
/**
* Construct a detached guard: the span is held with NO thread-local
* Scope, so the guard carries no context-stack binding and is safe
* to move to and destroy on another thread.
* @param s The span to guard.
*/
Impl(opentelemetry::nostd::shared_ptr<otel_trace::Span> s, Detached) : span(std::move(s))
{
}
~Impl()
{
// A live Scope (scope engaged) must be popped on the thread that
// pushed it; ending on any other thread corrupts that thread's
// context stack. A detached guard (scope == nullopt) carries no
// binding and may be destroyed anywhere, so the check is skipped.
XRPL_ASSERT(
!scope.has_value() || owner == std::this_thread::get_id(),
"xrpl::telemetry::SpanGuard::Impl::~Impl : scoped guard destroyed on "
"constructing thread");
if (span)
span->End();
}
@@ -155,6 +115,8 @@ struct SpanGuard::Impl
SpanGuard::SpanGuard() = default;
SpanGuard::~SpanGuard() = default;
SpanGuard::SpanGuard(SpanGuard&&) noexcept = default;
SpanGuard&
SpanGuard::operator=(SpanGuard&&) noexcept = default;
SpanGuard::SpanGuard(std::unique_ptr<Impl> impl) : impl_(std::move(impl))
{
@@ -237,7 +199,7 @@ SpanGuard::span(TraceCategory cat, std::string_view prefix, std::string_view nam
}
SpanGuard
SpanGuard::rootSpan(TraceCategory cat, std::string_view prefix, std::string_view name)
SpanGuard::freshRoot(TraceCategory cat, std::string_view prefix, std::string_view name)
{
auto* tel = Telemetry::getInstance();
if ((tel == nullptr) || !tel->isEnabled() || !isCategoryEnabled(*tel, cat))
@@ -327,43 +289,6 @@ SpanGuard::linkedSpan(std::string_view name, SpanContext const& linkCtx)
opts)));
}
SpanGuard
SpanGuard::detached() &&
{
if (!impl_)
return {};
// Popping the Scope (below, via impl_.reset()) must happen on the thread
// that pushed it; calling detached() elsewhere would pop the wrong stack.
XRPL_ASSERT(
!impl_->scope.has_value() || impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::SpanGuard::detached : called on constructing thread");
// Take the span out; the old Impl.span is now null so ~Impl won't End().
auto s = std::move(impl_->span);
// Resetting the old Impl destroys its Scope HERE, on the origin thread,
// popping this thread's context stack correctly. The returned guard holds
// the span with no Scope, so it is safe to move to another thread.
impl_.reset();
return SpanGuard(std::make_unique<Impl>(std::move(s), Impl::Detached{}));
}
// ===== Detach-in-place helpers =============================================
void
detachInPlace(std::optional<SpanGuard>& guard)
{
if (!guard || !*guard)
return;
guard.emplace(std::move(*guard).detached());
}
std::shared_ptr<SpanGuard>
detachInPlace(std::shared_ptr<SpanGuard> guard)
{
if (!guard || !*guard)
return guard;
return std::make_shared<SpanGuard>(std::move(*guard).detached());
}
// ===== Context capture =====================================================
SpanContext
@@ -476,6 +401,201 @@ SpanGuard::discard()
}
}
// ===== ScopedSpanGuard::ScopedImpl =========================================
struct ScopedSpanGuard::ScopedImpl
{
/**
* The unscoped guard that owns the span. Declared FIRST so it is
* destroyed AFTER `scope`: the Scope must pop before the span ends.
*/
SpanGuard guard;
/**
* Active OTel Scope binding the span to this thread's context stack.
* Present while the guard is active; reset() (via operator SpanGuard)
* pops it eagerly on the origin thread. Declared AFTER `guard` so
* destruction order pops the scope before the span ends.
*/
std::optional<otel_trace::Scope> scope;
/**
* Thread that constructed this ScopedImpl. The Scope is bound to
* this thread's context stack, so popping it (via ~Scope or reset())
* on a different thread corrupts that thread's stack. Checked in the
* destructor and operator SpanGuard() to turn a silent cross-thread
* corruption into an assertion failure in debug/test/fuzzing builds.
*/
std::thread::id owner{std::this_thread::get_id()};
/**
* Wrap a SpanGuard and activate its span on this thread. If the
* guard is active, push its span onto the thread-local context
* stack; a null guard leaves `scope` empty.
* @param g The span-owning guard to activate.
*/
explicit ScopedImpl(SpanGuard g) : guard(std::move(g))
{
if (guard)
scope.emplace(guard.impl_->span);
}
};
// ===== ScopedSpanGuard core lifecycle ======================================
ScopedSpanGuard::ScopedSpanGuard(SpanGuard&& guard)
: impl_(std::make_unique<ScopedImpl>(std::move(guard)))
{
}
ScopedSpanGuard::~ScopedSpanGuard()
{
// A live Scope must be popped on the thread that pushed it; destroying
// the guard on any other thread corrupts that thread's context stack.
// A null guard holds no Scope, so the check is skipped.
XRPL_ASSERT(
!impl_ || !impl_->scope.has_value() || impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::ScopedSpanGuard::~ScopedSpanGuard : destroyed on "
"constructing thread");
}
// ===== ScopedSpanGuard factory methods =====================================
ScopedSpanGuard::ScopedSpanGuard(TraceCategory cat, std::string_view prefix, std::string_view name)
: ScopedSpanGuard(SpanGuard::span(cat, prefix, name))
{
}
ScopedSpanGuard
ScopedSpanGuard::freshRoot(TraceCategory cat, std::string_view prefix, std::string_view name)
{
return ScopedSpanGuard(SpanGuard::freshRoot(cat, prefix, name));
}
ScopedSpanGuard
ScopedSpanGuard::childSpan(std::string_view name) const
{
return ScopedSpanGuard(impl_->guard.childSpan(name));
}
ScopedSpanGuard
ScopedSpanGuard::childSpan(std::string_view name, SpanContext const& parentCtx)
{
return ScopedSpanGuard(SpanGuard::childSpan(name, parentCtx));
}
ScopedSpanGuard
ScopedSpanGuard::linkedSpan(std::string_view name) const
{
return ScopedSpanGuard(impl_->guard.linkedSpan(name));
}
ScopedSpanGuard
ScopedSpanGuard::linkedSpan(std::string_view name, SpanContext const& linkCtx)
{
return ScopedSpanGuard(SpanGuard::linkedSpan(name, linkCtx));
}
// ===== ScopedSpanGuard handoff bridge ======================================
ScopedSpanGuard::
operator SpanGuard() &&
{
// The scope must be popped on the thread that pushed it; handing off
// elsewhere would pop the wrong stack.
XRPL_ASSERT(
impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::ScopedSpanGuard::operator SpanGuard : handoff on "
"constructing thread");
impl_->scope.reset(); // eager pop, on the origin thread
return std::move(impl_->guard);
}
// ===== ScopedSpanGuard context capture =====================================
SpanContext
ScopedSpanGuard::captureContext() const
{
return impl_->guard.captureContext();
}
// ===== ScopedSpanGuard forwarding methods ==================================
void
ScopedSpanGuard::setAttribute(std::string_view key, std::string_view value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, char const* value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, std::int64_t value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, double value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, bool value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setOk()
{
impl_->guard.setOk();
}
void
ScopedSpanGuard::setError(std::string_view description)
{
impl_->guard.setError(description);
}
void
ScopedSpanGuard::addEvent(std::string_view name)
{
impl_->guard.addEvent(name);
}
void
ScopedSpanGuard::recordException(std::exception const& e)
{
impl_->guard.recordException(e);
}
void
ScopedSpanGuard::discard()
{
// A live Scope must be popped on the thread that pushed it; discarding
// on any other thread corrupts that thread's context stack. A null guard
// holds no Scope, so the check is skipped.
XRPL_ASSERT(
!impl_ || !impl_->scope.has_value() || impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::ScopedSpanGuard::discard : discarded on constructing thread");
// Pop the scope first (on this thread) so no span stays active on the
// stack, then discard the span via the owned guard.
impl_->scope.reset();
impl_->guard.discard();
}
ScopedSpanGuard::
operator bool() const
{
return impl_ && static_cast<bool>(impl_->guard);
}
} // namespace xrpl::telemetry
#endif // XRPL_ENABLE_TELEMETRY