// TODO: Should have a flag to tell the garbage collector to automatically determine how many iterations are needed
// It should then gather statistics such as how many objects has been created since last run, and how many objects
// are destroyed per iteration, and how many objects are detected as cyclic garbage per iteration.
// It should try to reach a stable number of objects, i.e. so that on average the number of objects added to
// the garbage collector is the same as the number of objects destroyed. And it should try to minimize the number
// of iterations of detections that must be executed per cycle while still identifying the cyclic garbage
// These variables should also be available for inspection through the gcstatistics.
int asCGarbageCollector::GarbageCollect(asDWORD flags, asUINT iterations)
{
// If the GC is already processing in another thread, then don't enter here again
if( TRYENTERCRITICALSECTION(gcCollecting) )
{
// If the GC is already processing in this thread, then don't enter here again
if( isProcessing )
{
LEAVECRITICALSECTION(gcCollecting);
return 1;
}
isProcessing = true;
bool doDetect = (flags & asGC_DETECT_GARBAGE) || !(flags & asGC_DESTROY_GARBAGE);
bool doDestroy = (flags & asGC_DESTROY_GARBAGE) || !(flags & asGC_DETECT_GARBAGE);
if( flags & asGC_FULL_CYCLE )
{
// Reset the state
if( doDetect )
{
// Move all new objects to the old list, so we guarantee that all is detected
MoveAllObjectsToOldList();
detectState = clearCounters_init;
}
if( doDestroy )
{
destroyNewState = destroyGarbage_init;
destroyOldState = destroyGarbage_init;
}
// The full cycle only works with the objects in the old list so that the
// set of objects scanned for garbage is fixed even if new objects are added
// by other threads in parallel.
unsigned int count = (unsigned int)(gcOldObjects.GetLength());
for(;;)
{
// Detect all garbage with cyclic references
if( doDetect )
while( IdentifyGarbageWithCyclicRefs() == 1 ) {}
// Now destroy all known garbage
if( doDestroy )
{
if( !doDetect )
while( DestroyNewGarbage() == 1 ) {}
while( DestroyOldGarbage() == 1 ) {}
}
// Run another iteration if any garbage was destroyed
if( count != (unsigned int)(gcOldObjects.GetLength()) )
count = (unsigned int)(gcOldObjects.GetLength());
else
break;
}
isProcessing = false;
LEAVECRITICALSECTION(gcCollecting);
return 0;
}
else
{
while( iterations-- > 0 )
{
// Destroy the garbage that we know of
if( doDestroy )
{
DestroyNewGarbage();
DestroyOldGarbage();
}
// Run another incremental step of the identification of cyclic references
if( doDetect && gcOldObjects.GetLength() > 0 )
IdentifyGarbageWithCyclicRefs();
}
}
isProcessing = false;
LEAVECRITICALSECTION(gcCollecting);
}
// Return 1 to indicate that the cycle wasn't finished
return 1;
}
int asCGarbageCollector::GarbageCollect(asDWORD flags, asUINT iterations)
{
// If the GC is already processing in another thread, then don't enter here again
if( TRYENTERCRITICALSECTION(gcCollecting) )
{
// If the GC is already processing in this thread, then don't enter here again
if( isProcessing )
{
LEAVECRITICALSECTION(gcCollecting);
return 1;
}
isProcessing = true;
bool doDetect = (flags & asGC_DETECT_GARBAGE) || !(flags & asGC_DESTROY_GARBAGE);
bool doDestroy = (flags & asGC_DESTROY_GARBAGE) || !(flags & asGC_DETECT_GARBAGE);
if( flags & asGC_FULL_CYCLE )
{
// Reset the state
if( doDetect )
{
// Move all new objects to the old list, so we guarantee that all is detected
MoveAllObjectsToOldList();
detectState = clearCounters_init;
}
if( doDestroy )
destroyOldState = destroyGarbage_init;
// The full cycle only works with the objects in the old list so that the
// set of objects scanned for garbage is fixed even if new objects are added
// by other threads in parallel.
unsigned int count = (unsigned int)(gcOldObjects.GetLength());
for(;;)
{
// Detect all garbage with cyclic references
if( doDetect )
while( IdentifyGarbageWithCyclicRefs() == 1 ) {}
// Now destroy all known garbage
if( doDestroy )
while( DestroyOldGarbage() == 1 ) {}
// Run another iteration if any garbage was destroyed
if( count != (unsigned int)(gcOldObjects.GetLength()) )
count = (unsigned int)(gcOldObjects.GetLength());
else
{
// Let the engine destroy the types that reached refCount 0
// If none were destroyed, then leave the GC
// TODO: The asCObjectType should destroy its content when refCount reaches 0
// since no-one is using them. The registered types should have their
// refcount increased by the config groups. Doing it like that will allow
// me to remove this call to ClearUnusedTypes() that the GC really
// shouldn't be calling.
if( engine->ClearUnusedTypes() == 0 )
break;
}
}
isProcessing = false;
LEAVECRITICALSECTION(gcCollecting);
return 0;
}
else
{
while( iterations-- > 0 )
{
// Destroy the garbage that we know of
if( doDestroy )
{
DestroyNewGarbage();
DestroyOldGarbage();
}
// Run another incremental step of the identification of cyclic references
if( doDetect && gcOldObjects.GetLength() > 0 )
IdentifyGarbageWithCyclicRefs();
}
}
isProcessing = false;
LEAVECRITICALSECTION(gcCollecting);
}
// Return 1 to indicate that the cycle wasn't finished
return 1;
}