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[Loki-lib-cvs] SF.net SVN: loki-lib:[1176] trunk/src/LevelMutex.cpp
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From: <ric...@us...> - 2011-11-07 23:55:37
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Revision: 1176
http://loki-lib.svn.sourceforge.net/loki-lib/?rev=1176&view=rev
Author: rich_sposato
Date: 2011-11-07 23:55:30 +0000 (Mon, 07 Nov 2011)
Log Message:
-----------
Added Memento class to prove strong exception safety. Removed useless lines.
Modified Paths:
--------------
trunk/src/LevelMutex.cpp
Modified: trunk/src/LevelMutex.cpp
===================================================================
--- trunk/src/LevelMutex.cpp 2011-11-07 23:54:58 UTC (rev 1175)
+++ trunk/src/LevelMutex.cpp 2011-11-07 23:55:30 UTC (rev 1176)
@@ -232,6 +232,38 @@
// ----------------------------------------------------------------------------
+LevelMutexInfo::Memento::Memento( const volatile LevelMutexInfo & mutex ) :
+ m_level( mutex.m_level ),
+ m_count( mutex.m_count ),
+ m_previous( mutex.m_previous ),
+ m_locked( mutex.IsLockedByCurrentThreadImpl() )
+{
+ assert( this != nullptr );
+}
+
+// ----------------------------------------------------------------------------
+
+bool LevelMutexInfo::Memento::operator == ( const volatile LevelMutexInfo & mutex ) const
+{
+ assert( this != nullptr );
+
+ if ( m_locked && mutex.IsLockedByCurrentThreadImpl() )
+ {
+ // If the current thread still has a lock on the mutex, then make
+ // sure no values have changed.
+ if ( m_level != mutex.m_level )
+ return false;
+ if ( m_count != mutex.m_count )
+ return false;
+ if ( m_previous != mutex.m_previous )
+ return false;
+ }
+
+ return true;
+}
+
+// ----------------------------------------------------------------------------
+
LevelMutexInfo::MutexUndoer::MutexUndoer( MutexContainer & mutexes ) :
m_mutexes( mutexes ),
m_here( mutexes.end() )
@@ -572,6 +604,14 @@
// ----------------------------------------------------------------------------
+bool LevelMutexInfo::IsValid( void ) const
+{
+ const volatile LevelMutexInfo * pThis = const_cast< const volatile LevelMutexInfo * >( this );
+ return pThis->IsValid();
+}
+
+// ----------------------------------------------------------------------------
+
void LevelMutexInfo::IncrementCount( void ) volatile
{
assert( IsValid() );
@@ -592,8 +632,20 @@
bool LevelMutexInfo::IsLockedByCurrentThread( void ) const volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoChangeOrThrow checker( this, &IsValid() ); (void)checker; )
+ // This function could call CheckFor::NoThrowOrChange - except that this function
+ // gets called by various functions that are called to clean up after an exception
+ // is thrown
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoChange checker( this, &LevelMutexInfo::IsValid );
+ (void)checker;
+ )
+ return IsLockedByCurrentThreadImpl();
+}
+// ----------------------------------------------------------------------------
+
+bool LevelMutexInfo::IsLockedByCurrentThreadImpl( void ) const volatile
+{
if ( !IsLocked() )
return false;
const volatile LevelMutexInfo * mutex = s_currentMutex;
@@ -608,9 +660,30 @@
// ----------------------------------------------------------------------------
+bool LevelMutexInfo::IsNotLockedByCurrentThread( void ) const volatile
+{
+ if ( !IsLocked() )
+ return true;
+
+ const volatile LevelMutexInfo * mutex = s_currentMutex;
+ while ( nullptr != mutex )
+ {
+ if ( this == mutex )
+ return false;
+ mutex = mutex->m_previous;
+ }
+
+ return true;
+}
+
+// ----------------------------------------------------------------------------
+
bool LevelMutexInfo::IsRecentLock( void ) const volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoChangeOrThrow checker( this, &IsValid() ); (void)checker; )
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoThrowOrChange checker( this, &LevelMutexInfo::IsValid );
+ (void)checker;
+ )
if ( 0 == m_count )
return false;
@@ -631,7 +704,10 @@
bool LevelMutexInfo::IsRecentLock( std::size_t count ) const volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoChangeOrThrow checker( this, &IsValid() ); (void)checker; )
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoThrowOrChange checker( this, &LevelMutexInfo::IsValid );
+ (void)checker;
+ )
if ( 0 == count )
return false;
@@ -651,7 +727,10 @@
bool LevelMutexInfo::IsLockedByAnotherThread( void ) const volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoChangeOrThrow checker( this, &IsValid() ); (void)checker; )
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoThrowOrChange checker( this, &LevelMutexInfo::IsValid );
+ (void)checker;
+ )
if ( !IsLocked() )
return false;
@@ -664,14 +743,31 @@
// ----------------------------------------------------------------------------
-void LevelMutexInfo::PostLock( void ) volatile
+bool LevelMutexInfo::PostLockValidator( void ) const volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoThrow checker( this, &IsValid() ); (void)checker; )
assert( 0 == m_count );
assert( nullptr == m_previous );
assert( this != s_currentMutex );
assert( !IsLockedByCurrentThread() );
+ return true;
+}
+
+// ----------------------------------------------------------------------------
+
+void LevelMutexInfo::PostLock( void ) volatile
+{
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoThrow checker( this, &LevelMutexInfo::IsValid,
+ &LevelMutexInfo::PostLockValidator, &LevelMutexInfo::IsLockedByCurrentThreadImpl );
+ (void)checker;
+ )
+
+ /** Of the three data members PostLock must modify, it should change the count
+ before changing the other two. The IsLocked function uses the count to see if
+ the mutex is locked, so changing this first stops other threads from trying to
+ lock the object before this thread can modify the other two data members.
+ */
m_count = 1;
m_previous = s_currentMutex;
s_currentMutex = this;
@@ -679,14 +775,33 @@
// ----------------------------------------------------------------------------
-void LevelMutexInfo::PreUnlock( void ) volatile
+bool LevelMutexInfo::PreUnlockValidator( void ) const volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoThrow checker( this, &IsValid() ); (void)checker; )
assert( 1 == m_count );
assert( nullptr != s_currentMutex );
assert( this == s_currentMutex );
assert( IsLockedByCurrentThread() );
+ return true;
+}
+
+// ----------------------------------------------------------------------------
+
+void LevelMutexInfo::PreUnlock( void ) volatile
+{
+ LOKI_MUTEX_DEBUG_CODE(
+ // This must use CheckFor::Invariants instead of CheckFor::NoThrow because the
+ // function gets called when MultiLock has to clean up after an exception.
+ CheckFor::Invariants checker( this, &LevelMutexInfo::IsValid,
+ &LevelMutexInfo::PreUnlockValidator, &LevelMutexInfo::IsNotLockedByCurrentThread );
+ (void)checker;
+ )
+
+ /** Of the three data members PostLock must modify, it should change the count
+ after changing the other two. The IsLocked function uses the count to see if
+ the mutex is locked, so changing this last stops other threads from trying to
+ lock the object before this thread can modify the other two data members.
+ */
s_currentMutex = m_previous;
m_previous = nullptr;
m_count = 0;
@@ -696,7 +811,10 @@
MutexErrors::Type LevelMutexInfo::PreLockCheck( bool forTryLock ) volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoThrow checker( this, &IsValid() ); (void)checker; )
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoThrow checker( this, &LevelMutexInfo::IsValid );
+ (void)checker;
+ )
const unsigned int currentLevel = GetCurrentThreadsLevel();
if ( currentLevel < LevelMutexInfo::GetLevel() )
@@ -730,7 +848,10 @@
MutexErrors::Type LevelMutexInfo::PreUnlockCheck( void ) volatile
{
- LOKI_MUTEX_DEBUG_CODE( CheckFor::NoThrow checker( this, &IsValid() ); (void)checker; )
+ LOKI_MUTEX_DEBUG_CODE(
+ CheckFor::NoThrow checker( this, &LevelMutexInfo::IsValid );
+ (void)checker;
+ )
if ( 0 == m_count )
return MutexErrors::WasntLocked;
@@ -803,9 +924,6 @@
switch ( result )
{
case 0:
-//#if defined( DEBUG_LOKI_LEVEL_MUTEX )
-// cout << __FUNCTION__ << '\t' << __LINE__ << endl;
-//#endif
return;
case EBUSY:
throw MutexException( "pthread mutex already initialized!",
@@ -842,9 +960,6 @@
#if defined( _MSC_VER )
::DeleteCriticalSection( &m_mutex );
#else
-//#if defined( DEBUG_LOKI_LEVEL_MUTEX )
-// cout << __FUNCTION__ << '\t' << __LINE__ << endl;
-//#endif
::pthread_mutex_destroy( &m_mutex );
#endif
}
@@ -868,9 +983,6 @@
switch ( result )
{
case 0:
-//#if defined( DEBUG_LOKI_LEVEL_MUTEX )
-// cout << __FUNCTION__ << '\t' << __LINE__ << endl;
-//#endif
break;
default:
case EINVAL:
@@ -911,9 +1023,6 @@
switch ( result )
{
case 0:
-//#if defined( DEBUG_LOKI_LEVEL_MUTEX )
-// cout << __FUNCTION__ << '\t' << __LINE__ << endl;
-//#endif
return MutexErrors::Success;
default:
case EBUSY:
@@ -943,9 +1052,6 @@
if ( EPERM == result )
throw MutexException( "current thread did not lock this pthread mutex!",
GetLevel(), MutexErrors::NotLockedByThread );
-//#if defined( DEBUG_LOKI_LEVEL_MUTEX )
-// cout << __FUNCTION__ << '\t' << __LINE__ << endl;
-//#endif
#endif
return MutexErrors::Success;
}
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