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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef nsWrapperCacheInline_h___
#define nsWrapperCacheInline_h___
#include "nsWrapperCache.h"
#include "js/RootingAPI.h"
#include "js/TracingAPI.h"
inline JSObject* nsWrapperCache::GetWrapperPreserveColor() const {
JSObject* obj = GetWrapperMaybeDead();
if (obj && js::gc::EdgeNeedsSweepUnbarriered(&obj)) {
// The object has been found to be dead and is in the process of being
// finalized, so don't let the caller see it.
// Don't clear the cache though: this happens when a new wrapper is created
// for this native or when the wrapper is finalized.
return nullptr;
MOZ_ASSERT(obj == mWrapper);
return obj;
inline JSObject* nsWrapperCache::GetWrapper() const {
JSObject* obj = GetWrapperPreserveColor();
if (obj) {
return obj;
inline bool nsWrapperCache::HasKnownLiveWrapper() const {
// If we have a wrapper and it's not gray in the GC-marking sense, that means
// that we can't be cycle-collected. That's because the wrapper is being kept
// alive by the JS engine (and not just due to being traced from some
// cycle-collectable thing), and the wrapper holds us alive, so we know we're
// not collectable.
JSObject* o = GetWrapperPreserveColor();
return o && !JS::ObjectIsMarkedGray(o);
static void SearchGray(JS::GCCellPtr aGCThing, const char* aName,
void* aClosure) {
bool* hasGrayObjects = static_cast<bool*>(aClosure);
if (!*hasGrayObjects && aGCThing && JS::GCThingIsMarkedGray(aGCThing)) {
*hasGrayObjects = true;
inline bool nsWrapperCache::HasNothingToTrace(nsISupports* aThis) {
nsXPCOMCycleCollectionParticipant* participant = nullptr;
CallQueryInterface(aThis, &participant);
bool hasGrayObjects = false;
participant->Trace(aThis, TraceCallbackFunc(SearchGray), &hasGrayObjects);
return !hasGrayObjects;
inline bool nsWrapperCache::HasKnownLiveWrapperAndDoesNotNeedTracing(
nsISupports* aThis) {
return HasKnownLiveWrapper() && HasNothingToTrace(aThis);
inline void nsWrapperCache::MarkWrapperLive() {
// Just call GetWrapper and ignore the return value. It will do the
// gray-unmarking for us.
template <typename T>
inline void nsWrapperCache::UpdateWrapperForNewGlobal(T* aScriptObjectHolder,
JSObject* aNewWrapper) {
// If the new wrapper is in a different zone we must ensure the
// DropJSObjects/HoldJSObjects are called to move the holder to the new zone.
bool preserving = PreservingWrapper();
bool zoneChanged =
preserving && (JS::GetObjectZone(GetWrapperPreserveColor()) !=
if (zoneChanged) {
} else if (preserving) {
if (zoneChanged) {
} else if (preserving) {
#endif /* nsWrapperCache_h___ */