feat: Graceful shutdown with old web server (#2786)

- Stop accepting connections during graceful shutdown in the old web server
- Stop all the services before Clio exits
- Move cache saving into stop callback

src/data/CMakeLists.txt

@@ -5,6 +5,7 @@ target_sources(
           BackendCounters.cpp
           BackendInterface.cpp
           LedgerCache.cpp
+          LedgerCacheSaver.cpp
           LedgerHeaderCache.cpp
           cassandra/impl/Future.cpp
           cassandra/impl/Cluster.cpp

src/data/LedgerCache.cpp

@@ -265,7 +265,7 @@ LedgerCache::saveToFile(std::string const& path) const
     }
 
     impl::LedgerCacheFile file{path};
-    std::unique_lock const lock{mtx_};
+    std::shared_lock const lock{mtx_};
     impl::LedgerCacheFile::DataView const data{.latestSeq = latestSeq_, .map = map_, .deleted = deleted_};
     return file.write(data);
 }

src/data/LedgerCache.hpp

@@ -145,15 +145,8 @@ public:
     void
     waitUntilCacheContainsSeq(uint32_t seq) override;
 
-    /**
-     * @brief Save the cache to file
-     * @note This operation takes about 7 seconds and it keeps mtx_ exclusively locked
-     *
-     * @param path The file path to save the cache to
-     * @return An error as a string if any
-     */
     std::expected<void, std::string>
-    saveToFile(std::string const& path) const;
+    saveToFile(std::string const& path) const override;
 
     std::expected<void, std::string>
     loadFromFile(std::string const& path, uint32_t minLatestSequence) override;

src/data/LedgerCacheInterface.hpp

@@ -171,6 +171,16 @@ public:
     virtual void
     waitUntilCacheContainsSeq(uint32_t seq) = 0;
 
+    /**
+     * @brief Save the cache to file
+     * @note This operation takes about 7 seconds and it keeps a shared lock of mtx_
+     *
+     * @param path The file path to save the cache to
+     * @return An error as a string if any
+     */
+    [[nodiscard]] virtual std::expected<void, std::string>
+    saveToFile(std::string const& path) const = 0;
+
     /**
      * @brief Load the cache from file
      * @note This operation takes about 7 seconds and it keeps mtx_ exclusively locked

src/data/LedgerCacheSaver.cpp

@@ -0,0 +1,70 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "data/LedgerCacheSaver.hpp"
+
+#include "data/LedgerCacheInterface.hpp"
+#include "util/Assert.hpp"
+#include "util/Profiler.hpp"
+#include "util/log/Logger.hpp"
+
+#include <string>
+#include <thread>
+
+namespace data {
+
+LedgerCacheSaver::LedgerCacheSaver(util::config::ClioConfigDefinition const& config, LedgerCacheInterface const& cache)
+    : cacheFilePath_(config.maybeValue<std::string>("cache.file.path")), cache_(cache)
+{
+}
+
+LedgerCacheSaver::~LedgerCacheSaver()
+{
+    waitToFinish();
+}
+
+void
+LedgerCacheSaver::save()
+{
+    ASSERT(not savingThread_.has_value(), "Multiple save() calls are not allowed");
+    savingThread_ = std::thread([this]() {
+        if (not cacheFilePath_.has_value()) {
+            return;
+        }
+
+        LOG(util::LogService::info()) << "Saving ledger cache to " << *cacheFilePath_;
+        if (auto const [success, durationMs] = util::timed([&]() { return cache_.get().saveToFile(*cacheFilePath_); });
+            success.has_value()) {
+            LOG(util::LogService::info()) << "Successfully saved ledger cache in " << durationMs << " ms";
+        } else {
+            LOG(util::LogService::error()) << "Error saving LedgerCache to file";
+        }
+    });
+}
+
+void
+LedgerCacheSaver::waitToFinish()
+{
+    if (savingThread_.has_value() and savingThread_->joinable()) {
+        savingThread_->join();
+    }
+    savingThread_.reset();
+}
+
+}  // namespace data

src/data/LedgerCacheSaver.hpp

@@ -0,0 +1,93 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include "data/LedgerCacheInterface.hpp"
+#include "util/config/ConfigDefinition.hpp"
+
+#include <concepts>
+#include <functional>
+#include <optional>
+#include <string>
+#include <thread>
+
+namespace data {
+
+/**
+ * @brief A concept for a class that can save ledger cache asynchronously.
+ *
+ * This concept defines the interface requirements for any type that manages
+ * asynchronous saving of ledger cache to persistent storage.
+ */
+template <typename T>
+concept SomeLedgerCacheSaver = requires(T a) {
+    { a.save() } -> std::same_as<void>;
+    { a.waitToFinish() } -> std::same_as<void>;
+};
+
+/**
+ * @brief Manages asynchronous saving of ledger cache to a file.
+ *
+ * This class provides functionality to save the ledger cache to a file in a separate thread,
+ * allowing the main application to continue without blocking. The file path is configured
+ * through the application's configuration system.
+ */
+class LedgerCacheSaver {
+    std::optional<std::string> cacheFilePath_;
+    std::reference_wrapper<LedgerCacheInterface const> cache_;
+    std::optional<std::thread> savingThread_;
+
+public:
+    /**
+     * @brief Constructs a LedgerCacheSaver instance.
+     *
+     * @param config The configuration object containing the cache file path setting
+     * @param cache Reference to the ledger cache interface to be saved
+     */
+    LedgerCacheSaver(util::config::ClioConfigDefinition const& config, LedgerCacheInterface const& cache);
+
+    /**
+     * @brief Destructor that ensures the saving thread is properly joined.
+     *
+     * Waits for any ongoing save operation to complete before destruction.
+     */
+    ~LedgerCacheSaver();
+
+    /**
+     * @brief Initiates an asynchronous save operation of the ledger cache.
+     *
+     * Spawns a new thread that saves the ledger cache to the configured file path.
+     * If no file path is configured, the operation is skipped. Logs the progress
+     * and result of the save operation.
+     */
+    void
+    save();
+
+    /**
+     * @brief Waits for the saving thread to complete.
+     *
+     * Blocks until the saving operation finishes if a thread is currently active.
+     * Safe to call multiple times or when no save operation is in progress.
+     */
+    void
+    waitToFinish();
+};
+
+}  // namespace data