corysanin/tubestation
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Bug 707313 - use special non-NULL next for weak maps not in the list. r=jimb

Browse Source
This commit is contained in:
Andrew McCreight
2012-01-06 11:30:09 -08:00
parent 2f83198d96
commit dc69c83cd8
3 changed files with 34 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
js/src/jsweakmap.h
View File

@@ -106,11 +106,14 @@ template <class Type> class DefaultMarkPolicy;
// provides default types for WeakMap's TracePolicy template parameter.
template <class Key, class Value> class DefaultTracePolicy;
// The value for the next pointer for maps not in the map list.
static WeakMapBase * const WeakMapNotInList = reinterpret_cast<WeakMapBase *>(1);
// Common base class for all WeakMap specializations. The collector uses this to call
// their markIteratively and sweep methods.
class WeakMapBase {
public:
WeakMapBase(JSObject *memOf) : memberOf(memOf), next(NULL) { }
WeakMapBase(JSObject *memOf) : memberOf(memOf), next(WeakMapNotInList) { }
virtual ~WeakMapBase() { }
void trace(JSTracer *tracer) {
@@ -120,9 +123,14 @@ class WeakMapBase {
// known-live WeakMaps to be scanned in the iterative marking phase, by
// markAllIteratively.
JS_ASSERT(!tracer->eagerlyTraceWeakMaps);
JSRuntime *rt = tracer->context->runtime;
next = rt->gcWeakMapList;
rt->gcWeakMapList = this;
// Add ourselves to the list if we are not already in the list. We can already
// be in the list if the weak map is marked more than once due delayed marking.
if (next == WeakMapNotInList) {
JSRuntime *rt = tracer->context->runtime;
next = rt->gcWeakMapList;
rt->gcWeakMapList = this;
}
} else {
// If we're not actually doing garbage collection, the keys won't be marked
// nicely as needed by the true ephemeral marking algorithm --- custom tracers
@@ -148,6 +156,9 @@ class WeakMapBase {
// Trace all delayed weak map bindings. Used by the cycle collector.
static void traceAllMappings(WeakMapTracer *tracer);
// Remove everything from the live weak map list.
static void resetWeakMapList(JSRuntime *rt);
protected:
// Instance member functions called by the above. Instantiations of WeakMap override
// these with definitions appropriate for their Key and Value types.
@@ -161,7 +172,10 @@ class WeakMapBase {
private:
// Link in a list of WeakMaps to mark iteratively and sweep in this garbage
// collection, headed by JSRuntime::gcWeakMapList.
// collection, headed by JSRuntime::gcWeakMapList. The last element of the list
// has NULL as its next. Maps not in the list have WeakMapNotInList as their
// next. We must distinguish these cases to avoid creating infinite lists
// when a weak map gets traced twice due to delayed marking.
WeakMapBase *next;
};