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Bug 668855, part 5: scan weak maps. r=gal

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This commit is contained in:
Andrew McCreight 2011-11-24 07:35:57 -05:00
parent bb93bea281
commit a526a1e44e
1 changed files with 35 additions and 0 deletions
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35
xpcom/base/nsCycleCollector.cpp
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@ -1092,6 +1092,7 @@ struct nsCycleCollector
void SelectPurple(GCGraphBuilder &builder);
void MarkRoots(GCGraphBuilder &builder);
void ScanRoots();
void ScanWeakMaps();
// returns whether anything was collected
bool CollectWhite(nsICycleCollectorListener *aListener);
@ -1989,6 +1990,38 @@ struct scanVisitor
PRUint32 &mWhiteNodeCount;
};
// Iterate over the WeakMaps. If we mark anything while iterating
// over the WeakMaps, we must iterate over all of the WeakMaps again.
void
nsCycleCollector::ScanWeakMaps()
{
bool anyChanged;
do {
anyChanged = false;
for (PRUint32 i = 0; i < mGraph.mWeakMaps.Length(); i++) {
WeakMapping *wm = &mGraph.mWeakMaps[i];
// If mMap or mKey are null, the original object was marked black.
uint32 mColor = wm->mMap ? wm->mMap->mColor : black;
uint32 kColor = wm->mKey ? wm->mKey->mColor : black;
PtrInfo *v = wm->mVal;
// All non-null weak mapping maps, keys and values are
// roots (in the sense of WalkFromRoots) in the cycle
// collector graph, and thus should have been colored
// either black or white in ScanRoots().
NS_ASSERTION(mColor != grey, "Uncolored weak map");
NS_ASSERTION(kColor != grey, "Uncolored weak map key");
NS_ASSERTION(v->mColor != grey, "Uncolored weak map value");
if (mColor == black && kColor == black && v->mColor != black) {
GraphWalker<ScanBlackVisitor>(ScanBlackVisitor(mWhiteNodeCount)).Walk(v);
anyChanged = true;
}
}
} while (anyChanged);
}
void
nsCycleCollector::ScanRoots()
{
@ -1999,6 +2032,8 @@ nsCycleCollector::ScanRoots()
// NodePool::Enumerator.
GraphWalker<scanVisitor>(scanVisitor(mWhiteNodeCount)).WalkFromRoots(mGraph);
ScanWeakMaps();
#ifdef DEBUG_CC
// Sanity check: scan should have colored all grey nodes black or
// white. So we ensure we have no grey nodes at this point.