void Grid::PrintChildren(int NumofNode)
{
node* ptr = ReturnNode(NumofNode);
if (ptr != NULL)
{
cout << "Node = " << ptr->NumofNode << endl;
ptr->Left == NULL ?
cout << "Left Child = Null\n":
cout << "Left Child = " << ptr->Left->NumofNode << endl;
ptr->Right == NULL ?
cout << "Right Child = Null\n" :
cout << "Right Child = " << ptr->Right->NumofNode << endl;
}
else
{
cout << "Node is not in the tree\n";
}
}
int asCGarbageCollector::IdentifyGarbageWithCyclicRefs()
{
for(;;)
{
switch( detectState )
{
case clearCounters_init:
detectState = clearCounters_loop;
break;
case clearCounters_loop:
{
// Decrease reference counter for all objects removed from the map
asSMapNode<void*, asSIntTypePair> *cursor = 0;
gcMap.MoveFirst(&cursor);
if( cursor )
{
void *obj = gcMap.GetKey(cursor);
asSIntTypePair it = gcMap.GetValue(cursor);
engine->CallObjectMethod(obj, it.type->beh.release);
ReturnNode(gcMap.Remove(cursor));
return 1;
}
detectState = buildMap_init;
}
break;
case buildMap_init:
detectIdx = 0;
detectState = buildMap_loop;
break;
case buildMap_loop:
{
// Build a map of objects that will be checked, the map will
// hold the object pointer as key, and the gcCount and the
// object's type as value. As objects are added to the map the
// gcFlag must be set in the objects, so we can be verify if
// the object is accessed during the GC cycle.
// If an object is removed from the gcObjects list during the
// iteration of this step, it is possible that an object won't
// be used during the analyzing for cyclic references. This
// isn't a problem, as the next time the GC cycle starts the
// object will be verified.
if( detectIdx < gcOldObjects.GetLength() )
{
// Add the gc count for this object
asSObjTypePair gcObj = GetOldObjectAtIdx(detectIdx);
int refCount = 0;
if( gcObj.type->beh.gcGetRefCount )
refCount = engine->CallObjectMethodRetInt(gcObj.obj, gcObj.type->beh.gcGetRefCount);
if( refCount > 1 )
{
asSIntTypePair it = {refCount-1, gcObj.type};
gcMap.Insert(GetNode(gcObj.obj, it));
// Increment the object's reference counter when putting it in the map
engine->CallObjectMethod(gcObj.obj, gcObj.type->beh.addref);
// Mark the object so that we can
// see if it has changed since read
engine->CallObjectMethod(gcObj.obj, gcObj.type->beh.gcSetFlag);
}
detectIdx++;
// Let the application work a little
return 1;
}
else
detectState = countReferences_init;
}
break;
case countReferences_init:
{
gcMap.MoveFirst(&gcMapCursor);
detectState = countReferences_loop;
}
break;
case countReferences_loop:
{
// Call EnumReferences on all objects in the map to count the number
// of references reachable from between objects in the map. If all
// references for an object in the map is reachable from other objects
// in the map, then we know that no outside references are held for
// this object, thus it is a potential dead object in a circular reference.
// If the gcFlag is cleared for an object we consider the object alive
// and referenced from outside the GC, thus we don't enumerate its references.
// Any new objects created after this step in the GC cycle won't be
// in the map, and is thus automatically considered alive.
if( gcMapCursor )
{
void *obj = gcMap.GetKey(gcMapCursor);
asCObjectType *type = gcMap.GetValue(gcMapCursor).type;
gcMap.MoveNext(&gcMapCursor, gcMapCursor);
if( engine->CallObjectMethodRetBool(obj, type->beh.gcGetFlag) )
{
engine->CallObjectMethod(obj, engine, type->beh.gcEnumReferences);
}
// Allow the application to work a little
return 1;
}
else
detectState = detectGarbage_init;
}
break;
case detectGarbage_init:
{
gcMap.MoveFirst(&gcMapCursor);
liveObjects.SetLength(0);
detectState = detectGarbage_loop1;
}
break;
case detectGarbage_loop1:
{
// All objects that are known not to be dead must be removed from the map,
// along with all objects they reference. What remains in the map after
// this pass is sure to be dead objects in circular references.
// An object is considered alive if its gcFlag is cleared, or all the
// references were not found in the map.
// Add all alive objects from the map to the liveObjects array
if( gcMapCursor )
{
asSMapNode<void*, asSIntTypePair> *cursor = gcMapCursor;
gcMap.MoveNext(&gcMapCursor, gcMapCursor);
void *obj = gcMap.GetKey(cursor);
asSIntTypePair it = gcMap.GetValue(cursor);
bool gcFlag = engine->CallObjectMethodRetBool(obj, it.type->beh.gcGetFlag);
if( !gcFlag || it.i > 0 )
{
liveObjects.PushLast(obj);
}
// Allow the application to work a little
return 1;
}
else
detectState = detectGarbage_loop2;
}
break;
case detectGarbage_loop2:
{
// In this step we are actually removing the alive objects from the map.
// As the object is removed, all the objects it references are added to the
// liveObjects list, by calling EnumReferences. Only objects still in the map
// will be added to the liveObjects list.
if( liveObjects.GetLength() )
{
void *gcObj = liveObjects.PopLast();
asCObjectType *type = 0;
// Remove the object from the map to mark it as alive
asSMapNode<void*, asSIntTypePair> *cursor = 0;
if( gcMap.MoveTo(&cursor, gcObj) )
{
type = gcMap.GetValue(cursor).type;
ReturnNode(gcMap.Remove(cursor));
// We need to decrease the reference count again as we remove the object from the map
engine->CallObjectMethod(gcObj, type->beh.release);
// Enumerate all the object's references so that they too can be marked as alive
engine->CallObjectMethod(gcObj, engine, type->beh.gcEnumReferences);
}
// Allow the application to work a little
return 1;
}
else
detectState = verifyUnmarked_init;
}
break;
case verifyUnmarked_init:
gcMap.MoveFirst(&gcMapCursor);
detectState = verifyUnmarked_loop;
break;
case verifyUnmarked_loop:
{
// In this step we must make sure that none of the objects still in the map
// has been touched by the application. If they have then we must run the
// detectGarbage loop once more.
if( gcMapCursor )
{
void *gcObj = gcMap.GetKey(gcMapCursor);
asCObjectType *type = gcMap.GetValue(gcMapCursor).type;
bool gcFlag = engine->CallObjectMethodRetBool(gcObj, type->beh.gcGetFlag);
if( !gcFlag )
{
// The unmarked object was touched, rerun the detectGarbage loop
detectState = detectGarbage_init;
}
else
gcMap.MoveNext(&gcMapCursor, gcMapCursor);
// Allow the application to work a little
return 1;
}
else
{
// No unmarked object was touched, we can now be sure
// that objects that have gcCount == 0 really is garbage
detectState = breakCircles_init;
}
}
break;
case breakCircles_init:
{
gcMap.MoveFirst(&gcMapCursor);
detectState = breakCircles_loop;
}
break;
case breakCircles_loop:
case breakCircles_haveGarbage:
{
// All objects in the map are now known to be dead objects
// kept alive through circular references. To be able to free
// these objects we need to force the breaking of the circle
// by having the objects release their references.
if( gcMapCursor )
{
numDetected++;
void *gcObj = gcMap.GetKey(gcMapCursor);
asCObjectType *type = gcMap.GetValue(gcMapCursor).type;
engine->CallObjectMethod(gcObj, engine, type->beh.gcReleaseAllReferences);
gcMap.MoveNext(&gcMapCursor, gcMapCursor);
detectState = breakCircles_haveGarbage;
// Allow the application to work a little
return 1;
}
else
{
// If no garbage was detected we can finish now
if( detectState != breakCircles_haveGarbage )
{
// Restart the GC
detectState = clearCounters_init;
return 0;
}
else
{
// Restart the GC
detectState = clearCounters_init;
return 1;
}
}
}
} // switch
}
// Shouldn't reach this point
UNREACHABLE_RETURN;
}
