From 7cc3fb098df221f083da1d81d2327a0a5f22edf5 Mon Sep 17 00:00:00 2001 From: Mattes D Date: Tue, 17 Jan 2017 22:38:04 +0100 Subject: DeadlockDetect now lists some tracked CS's stats. --- src/OSSupport/CriticalSection.h | 39 ++++++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 13 deletions(-) (limited to 'src/OSSupport/CriticalSection.h') diff --git a/src/OSSupport/CriticalSection.h b/src/OSSupport/CriticalSection.h index 6ea18051a..917957aeb 100644 --- a/src/OSSupport/CriticalSection.h +++ b/src/OSSupport/CriticalSection.h @@ -9,27 +9,40 @@ class cCriticalSection { + friend class cDeadlockDetect; // Allow the DeadlockDetect to read the internals, so that it may output some statistics + public: void Lock(void); void Unlock(void); - // IsLocked / IsLockedByCurrentThread are only used in ASSERT statements, but because of the changes with ASSERT they must always be defined - // The fake versions (in Release) will not effect the program in any way - #ifdef _DEBUG - cCriticalSection(void); - bool IsLocked(void); - bool IsLockedByCurrentThread(void); - #else - bool IsLocked(void) { return false; } - bool IsLockedByCurrentThread(void) { return false; } - #endif // _DEBUG + cCriticalSection(void); + + /** Returns true if the CS is currently locked. + Note that since it relies on the m_RecursionCount value, it is inherently thread-unsafe, prone to false positives. + Also, due to multithreading, the state can change between this when function is evaluated and the returned value is used. + To be used in ASSERT(IsLocked()) only. */ + bool IsLocked(void); + + /** Returns true if the CS is currently locked by the thread calling this function. + Note that since it relies on the m_RecursionCount value, it is inherently thread-unsafe, prone to false positives. + Also, due to multithreading, the state can change between this when function is evaluated and the returned value is used. + To be used in ASSERT(IsLockedByCurrentThread()) only. */ + bool IsLockedByCurrentThread(void); private: - #ifdef _DEBUG - int m_IsLocked; // Number of times this CS is locked + /** Number of times that this CS is currently locked (levels of recursion). Zero if not locked. + Note that this value should be considered true only when the CS is locked; without the lock, it is UndefinedBehavior to even read it, + but making it std::atomic would impose too much of a runtime penalty. + It is only ever read without the lock in the DeadlockDetect, where the server is terminating anyway. */ + int m_RecursionCount; + + /** ID of the thread that is currently holding the CS. + Note that this value should be considered true only when the CS is locked; without the lock, it is UndefinedBehavior to even read it, + but making it std::atomic would impose too much of a runtime penalty. + When unlocked, the value stored here has no meaning, it may be an ID of a previous holder, or it could be any garbage. + It is only ever read without the lock in the DeadlockDetect, where the server is terminating anyway. */ std::thread::id m_OwningThreadID; - #endif // _DEBUG std::recursive_mutex m_Mutex; } ALIGN_8; -- cgit v1.2.3