log: make m_limiter a shared_ptr

This allows us to safely and explicitly manage the dual dependency
on the limiter: one for the Logger, and one for the CScheduler.

Github-Pull: #33011
Rebased-From: 3d630c2544

src/init.cpp

@@ -1384,7 +1384,7 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
         }
     }, std::chrono::minutes{5});
 
-    LogInstance().SetRateLimiting(std::make_unique<BCLog::LogRateLimiter>(
+    LogInstance().SetRateLimiting(BCLog::LogRateLimiter::Create(
         [&scheduler](auto func, auto window) { scheduler.scheduleEvery(std::move(func), window); },
         BCLog::RATELIMIT_MAX_BYTES,
         BCLog::RATELIMIT_WINDOW));

src/logging.cpp

@@ -371,12 +371,19 @@ static size_t MemUsage(const BCLog::Logger::BufferedLog& buflog)
            memusage::MallocUsage(sizeof(memusage::list_node<BCLog::Logger::BufferedLog>));
 }
 
-BCLog::LogRateLimiter::LogRateLimiter(
-    SchedulerFunction scheduler_func,
-    uint64_t max_bytes,
-    std::chrono::seconds reset_window) : m_max_bytes{max_bytes}, m_reset_window{reset_window}
+BCLog::LogRateLimiter::LogRateLimiter(uint64_t max_bytes, std::chrono::seconds reset_window)
+    : m_max_bytes{max_bytes}, m_reset_window{reset_window} {}
+
+std::shared_ptr<BCLog::LogRateLimiter> BCLog::LogRateLimiter::Create(
+    SchedulerFunction&& scheduler_func, uint64_t max_bytes, std::chrono::seconds reset_window)
 {
-    scheduler_func([this] { Reset(); }, reset_window);
+    auto limiter{std::shared_ptr<LogRateLimiter>(new LogRateLimiter(max_bytes, reset_window))};
+    std::weak_ptr<LogRateLimiter> weak_limiter{limiter};
+    auto reset = [weak_limiter] {
+        if (auto shared_limiter{weak_limiter.lock()}) shared_limiter->Reset();
+    };
+    scheduler_func(reset, limiter->m_reset_window);
+    return limiter;
 }
 
 BCLog::LogRateLimiter::Status BCLog::LogRateLimiter::Consume(

src/logging.h

@@ -18,6 +18,7 @@
 #include <cstring>
 #include <functional>
 #include <list>
+#include <memory>
 #include <mutex>
 #include <source_location>
 #include <string>
@@ -130,6 +131,7 @@ namespace BCLog {
         std::unordered_map<std::source_location, Stats, SourceLocationHasher, SourceLocationEqual> m_source_locations GUARDED_BY(m_mutex);
         //! Whether any log locations are suppressed. Cached view on m_source_locations for performance reasons.
         std::atomic<bool> m_suppression_active{false};
+        LogRateLimiter(uint64_t max_bytes, std::chrono::seconds reset_window);
 
     public:
         using SchedulerFunction = std::function<void(std::function<void()>, std::chrono::milliseconds)>;
@@ -141,7 +143,10 @@ namespace BCLog {
          *                          location.
          * @param reset_window      Time window after which the stats are reset.
          */
-        LogRateLimiter(SchedulerFunction scheduler_func, uint64_t max_bytes, std::chrono::seconds reset_window);
+        static std::shared_ptr<LogRateLimiter> Create(
+            SchedulerFunction&& scheduler_func,
+            uint64_t max_bytes,
+            std::chrono::seconds reset_window);
         //! Maximum number of bytes logged per location per window.
         const uint64_t m_max_bytes;
         //! Interval after which the window is reset.
@@ -186,7 +191,7 @@ namespace BCLog {
         size_t m_buffer_lines_discarded GUARDED_BY(m_cs){0};
 
         //! Manages the rate limiting of each log location.
-        std::unique_ptr<LogRateLimiter> m_limiter GUARDED_BY(m_cs);
+        std::shared_ptr<LogRateLimiter> m_limiter GUARDED_BY(m_cs);
 
         //! Category-specific log level. Overrides `m_log_level`.
         std::unordered_map<LogFlags, Level> m_category_log_levels GUARDED_BY(m_cs);
@@ -255,7 +260,7 @@ namespace BCLog {
         /** Only for testing */
         void DisconnectTestLogger() EXCLUSIVE_LOCKS_REQUIRED(!m_cs);
 
-        void SetRateLimiting(std::unique_ptr<LogRateLimiter>&& limiter) EXCLUSIVE_LOCKS_REQUIRED(!m_cs)
+        void SetRateLimiting(std::shared_ptr<LogRateLimiter> limiter) EXCLUSIVE_LOCKS_REQUIRED(!m_cs)
         {
             StdLockGuard scoped_lock(m_cs);
             m_limiter = std::move(limiter);

src/test/logging_tests.cpp

@@ -69,6 +69,7 @@ struct LogSetup : public BasicTestingSetup {
 
         LogInstance().SetLogLevel(BCLog::Level::Debug);
         LogInstance().SetCategoryLogLevel({});
+        LogInstance().SetRateLimiting(nullptr);
     }
 
     ~LogSetup()
@@ -82,6 +83,7 @@ struct LogSetup : public BasicTestingSetup {
         LogInstance().m_log_sourcelocations = prev_log_sourcelocations;
         LogInstance().SetLogLevel(prev_log_level);
         LogInstance().SetCategoryLogLevel(prev_category_levels);
+        LogInstance().SetRateLimiting(nullptr);
     }
 };
 
@@ -309,7 +311,8 @@ BOOST_AUTO_TEST_CASE(logging_log_rate_limiter)
     uint64_t max_bytes{1024};
     auto reset_window{1min};
     auto sched_func = [&scheduler](auto func, auto window) { scheduler.scheduleEvery(std::move(func), window); };
-    BCLog::LogRateLimiter limiter{sched_func, max_bytes, reset_window};
+    auto limiter_{BCLog::LogRateLimiter::Create(sched_func, max_bytes, reset_window)};
+    auto& limiter{*limiter_};
 
     using Status = BCLog::LogRateLimiter::Status;
     auto source_loc_1{std::source_location::current()};
@@ -405,8 +408,7 @@ BOOST_FIXTURE_TEST_CASE(logging_filesize_rate_limit, LogSetup)
     CScheduler scheduler{};
     scheduler.m_service_thread = std::thread([&] { scheduler.serviceQueue(); });
     auto sched_func = [&scheduler](auto func, auto window) { scheduler.scheduleEvery(std::move(func), window); };
-    auto limiter = std::make_unique<BCLog::LogRateLimiter>(sched_func, 1024 * 1024, 20s);
-    LogInstance().SetRateLimiting(std::move(limiter));
+    LogInstance().SetRateLimiting(BCLog::LogRateLimiter::Create(sched_func, 1024 * 1024, 20s));
 
     // Log 1024-character lines (1023 plus newline) to make the math simple.
     std::string log_message(1023, 'a');