summaryrefslogtreecommitdiffstats
path: root/src/OSSupport
diff options
context:
space:
mode:
authorMattes D <github@xoft.cz>2017-01-17 22:38:04 +0100
committerMattes D <github@xoft.cz>2017-01-18 09:03:05 +0100
commit7cc3fb098df221f083da1d81d2327a0a5f22edf5 (patch)
treede9232cbf239800ea1e7a71cf52086509a9472ea /src/OSSupport
parentDebuggers: Added a deadlock simulation command. (diff)
downloadcuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.tar
cuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.tar.gz
cuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.tar.bz2
cuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.tar.lz
cuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.tar.xz
cuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.tar.zst
cuberite-7cc3fb098df221f083da1d81d2327a0a5f22edf5.zip
Diffstat (limited to '')
-rw-r--r--src/OSSupport/CriticalSection.cpp24
-rw-r--r--src/OSSupport/CriticalSection.h39
2 files changed, 34 insertions, 29 deletions
diff --git a/src/OSSupport/CriticalSection.cpp b/src/OSSupport/CriticalSection.cpp
index 2e533676d..27284acb0 100644
--- a/src/OSSupport/CriticalSection.cpp
+++ b/src/OSSupport/CriticalSection.cpp
@@ -9,12 +9,10 @@
////////////////////////////////////////////////////////////////////////////////
// cCriticalSection:
-#ifdef _DEBUG
-cCriticalSection::cCriticalSection()
+cCriticalSection::cCriticalSection():
+ m_RecursionCount(0)
{
- m_IsLocked = 0;
}
-#endif // _DEBUG
@@ -24,10 +22,8 @@ void cCriticalSection::Lock()
{
m_Mutex.lock();
- #ifdef _DEBUG
- m_IsLocked += 1;
- m_OwningThreadID = std::this_thread::get_id();
- #endif // _DEBUG
+ m_RecursionCount += 1;
+ m_OwningThreadID = std::this_thread::get_id();
}
@@ -36,10 +32,8 @@ void cCriticalSection::Lock()
void cCriticalSection::Unlock()
{
- #ifdef _DEBUG
- ASSERT(m_IsLocked > 0);
- m_IsLocked -= 1;
- #endif // _DEBUG
+ ASSERT(IsLockedByCurrentThread());
+ m_RecursionCount -= 1;
m_Mutex.unlock();
}
@@ -48,10 +42,9 @@ void cCriticalSection::Unlock()
-#ifdef _DEBUG
bool cCriticalSection::IsLocked(void)
{
- return (m_IsLocked > 0);
+ return (m_RecursionCount > 0);
}
@@ -60,9 +53,8 @@ bool cCriticalSection::IsLocked(void)
bool cCriticalSection::IsLockedByCurrentThread(void)
{
- return ((m_IsLocked > 0) && (m_OwningThreadID == std::this_thread::get_id()));
+ return ((m_RecursionCount > 0) && (m_OwningThreadID == std::this_thread::get_id()));
}
-#endif // _DEBUG
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;