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Simplify CMutexLock 

o Remove unused Leave and GetLock functions
o Make Enter and TryEnter private.
o Simplify Enter and TryEnter.
  boost::unique_lock doesn't really know whether the
  mutex it wraps is locked or not when the defer_lock
  option is used.
  The boost::recursive_mutex does not expose this
  information, so unique_lock only infers this
  knowledge.  When taking the lock is defered, it
  (randomly) assumes that the lock is not taken.
  boost::unique_lock has the following definition:

        unique_lock(Mutex& m_,defer_lock_t):
            m(&m_),is_locked(false)
        {}

        bool owns_lock() const
        {
            return is_locked;
        }
  Thus it is a mistake to check owns_lock() in Enter
  and TryEnter - they will always return false.
This commit is contained in:
Alexander Kjeldaas 2012-11-11 03:11:13 -03:00
parent 6ca2ea2fa2
commit bfc9620799
1 changed files with 11 additions and 31 deletions
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42
src/sync.h
View File

@ -37,46 +37,31 @@ class CMutexLock
{
private:
boost::unique_lock<Mutex> lock;
public:
void Enter(const char* pszName, const char* pszFile, int nLine)
{
if (!lock.owns_lock())
{
EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
#ifdef DEBUG_LOCKCONTENTION
if (!lock.try_lock())
{
PrintLockContention(pszName, pszFile, nLine);
#endif
lock.lock();
#ifdef DEBUG_LOCKCONTENTION
}
#endif
}
}
void Leave()
{
if (lock.owns_lock())
if (!lock.try_lock())
{
lock.unlock();
LeaveCritical();
PrintLockContention(pszName, pszFile, nLine);
#endif
lock.lock();
#ifdef DEBUG_LOCKCONTENTION
}
#endif
}
bool TryEnter(const char* pszName, const char* pszFile, int nLine)
{
EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()), true);
lock.try_lock();
if (!lock.owns_lock())
{
EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()), true);
lock.try_lock();
if (!lock.owns_lock())
LeaveCritical();
}
LeaveCritical();
return lock.owns_lock();
}
public:
CMutexLock(Mutex& mutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) : lock(mutexIn, boost::defer_lock)
{
if (fTry)
@ -95,11 +80,6 @@ public:
{
return lock.owns_lock();
}
boost::unique_lock<Mutex> &GetLock()
{
return lock;
}
};
typedef CMutexLock<CCriticalSection> CCriticalBlock;