From 79467e3ec7c2d756c4d824f642ed3856a4e72883 Mon Sep 17 00:00:00 2001
From: Cory Fields <cory-nospam-@coryfields.com>
Date: Tue, 10 Mar 2026 20:13:49 +0000
Subject: [PATCH] threading: never require logging from sync.h

sync.h is low-level and should not require any other subsystems.

Move the lone remaining logging call to the .cpp. Any cost incurred by an
additional function call should be trivial compared to the logging itself.
---
 src/sync.cpp | 14 ++++++++++++++
 src/sync.h   | 22 +++++++++++++++-------
 2 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/sync.cpp b/src/sync.cpp
index e59f86b94fc..0e5c623d212 100644
--- a/src/sync.cpp
+++ b/src/sync.cpp
@@ -4,6 +4,7 @@
 
 #include <sync.h>
 
+#include <logging/timer.h>
 #include <tinyformat.h>
 #include <util/log.h>
 #include <util/strencodings.h>
@@ -19,6 +20,19 @@
 #include <utility>
 #include <vector>
 
+#ifdef DEBUG_LOCKCONTENTION
+
+template <typename LockType>
+void ContendedLock(std::string_view name, std::string_view file, int nLine, LockType& lock)
+{
+    LOG_TIME_MICROS_WITH_CATEGORY(strprintf("lock contention %s, %s:%d", name, file, nLine), BCLog::LOCK);
+    lock.lock();
+}
+template void ContendedLock(std::string_view name, std::string_view file, int nLine, std::unique_lock<std::mutex>& lock);
+template void ContendedLock(std::string_view name, std::string_view file, int nLine, std::unique_lock<std::recursive_mutex>& lock);
+
+#endif
+
 #ifdef DEBUG_LOCKORDER
 //
 // Early deadlock detection.
diff --git a/src/sync.h b/src/sync.h
index 548b51d9d16..00fdaae942b 100644
--- a/src/sync.h
+++ b/src/sync.h
@@ -6,10 +6,6 @@
 #ifndef BITCOIN_SYNC_H
 #define BITCOIN_SYNC_H
 
-#ifdef DEBUG_LOCKCONTENTION
-#include <logging/timer.h>
-#endif
-
 #include <threadsafety.h> // IWYU pragma: export
 #include <util/macros.h>
 
@@ -77,6 +73,16 @@ inline void DeleteLock(void* cs) {}
 inline bool LockStackEmpty() { return true; }
 #endif
 
+/*
+ * Called when a mutex fails to lock immediately because it is held by another
+ * thread, or spuriously. Responsible for locking the lock before returning.
+ */
+#ifdef DEBUG_LOCKCONTENTION
+
+template <typename LockType>
+void ContendedLock(std::string_view name, std::string_view file, int nLine, LockType& lock);
+#endif
+
 /**
  * Template mixin that adds -Wthread-safety locking annotations and lock order
  * checking to a subset of the mutex API.
@@ -151,10 +157,12 @@ private:
     {
         EnterCritical(pszName, pszFile, nLine, Base::mutex());
 #ifdef DEBUG_LOCKCONTENTION
-        if (Base::try_lock()) return;
-        LOG_TIME_MICROS_WITH_CATEGORY(strprintf("lock contention %s, %s:%d", pszName, pszFile, nLine), BCLog::LOCK);
-#endif
+        if (!Base::try_lock()) {
+            ContendedLock(pszName, pszFile, nLine, static_cast<Base&>(*this));
+        }
+#else
         Base::lock();
+#endif
     }
 
     bool TryEnter(const char* pszName, const char* pszFile, int nLine)