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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 http://mozilla.org/MPL/2.0/. */
+
+// We're dividing JS objects into 3 categories:
+//
+// 1. "real" roots, held by the JS engine itself or rooted through the root
+// and lock JS APIs. Roots from this category are considered black in the
+// cycle collector, any cycle they participate in is uncollectable.
+//
+// 2. certain roots held by C++ objects that are guaranteed to be alive.
+// Roots from this category are considered black in the cycle collector,
+// and any cycle they participate in is uncollectable. These roots are
+// traced from TraceNativeBlackRoots.
+//
+// 3. all other roots held by C++ objects that participate in cycle collection,
+// held by us (see TraceNativeGrayRoots). Roots from this category are
+// considered grey in the cycle collector; whether or not they are collected
+// depends on the objects that hold them.
+//
+// Note that if a root is in multiple categories the fact that it is in
+// category 1 or 2 that takes precedence, so it will be considered black.
+//
+// During garbage collection we switch to an additional mark color (gray) when
+// tracing inside TraceNativeGrayRoots. This allows us to walk those roots later
+// on and add all objects reachable only from them to the cycle collector.
+//
+// Phases:
+//
+// 1. marking of the roots in category 1 by having the JS GC do its marking
+// 2. marking of the roots in category 2 by having the JS GC call us back
+// (via JS_SetExtraGCRootsTracer) and running TraceNativeBlackRoots
+// 3. marking of the roots in category 3 by
+// TraceNativeGrayRootsInCollectingZones using an additional color (gray).
+// 4. end of GC, GC can sweep its heap
+//
+// At some later point, when the cycle collector runs:
+//
+// 5. walk gray objects and add them to the cycle collector, cycle collect
+//
+// JS objects that are part of cycles the cycle collector breaks will be
+// collected by the next JS GC.
+//
+// If WantAllTraces() is false the cycle collector will not traverse roots
+// from category 1 or any JS objects held by them. Any JS objects they hold
+// will already be marked by the JS GC and will thus be colored black
+// themselves. Any C++ objects they hold will have a missing (untraversed)
+// edge from the JS object to the C++ object and so it will be marked black
+// too. This decreases the number of objects that the cycle collector has to
+// deal with.
+// To improve debugging, if WantAllTraces() is true all JS objects are
+// traversed.
+
+#include "mozilla/CycleCollectedJSRuntime.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "js/Debug.h"
+#include "js/RealmOptions.h"
+#include "js/friend/DumpFunctions.h" // js::DumpHeap
+#include "js/GCAPI.h"
+#include "js/HeapAPI.h"
+#include "js/Object.h" // JS::GetClass, JS::GetCompartment, JS::GetPrivate
+#include "js/PropertyAndElement.h" // JS_DefineProperty
+#include "js/Warnings.h" // JS::SetWarningReporter
+#include "js/ShadowRealmCallbacks.h"
+#include "js/SliceBudget.h"
+#include "jsfriendapi.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/DebuggerOnGCRunnable.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/PerfStats.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/ProfilerMarkers.h"
+#include "mozilla/Sprintf.h"
+#include "mozilla/StaticPrefs_javascript.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/Unused.h"
+#include "mozilla/dom/AutoEntryScript.h"
+#include "mozilla/dom/DOMJSClass.h"
+#include "mozilla/dom/JSExecutionManager.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/PromiseBinding.h"
+#include "mozilla/dom/PromiseDebugging.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/ShadowRealmGlobalScope.h"
+#include "mozilla/dom/RegisterShadowRealmBindings.h"
+#include "nsContentUtils.h"
+#include "nsCycleCollectionNoteRootCallback.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsCycleCollector.h"
+#include "nsDOMJSUtils.h"
+#include "nsExceptionHandler.h"
+#include "nsJSUtils.h"
+#include "nsStringBuffer.h"
+#include "nsWrapperCache.h"
+#include "prenv.h"
+
+#if defined(XP_MACOSX)
+# include "nsMacUtilsImpl.h"
+#endif
+
+#include "nsThread.h"
+#include "nsThreadUtils.h"
+#include "xpcpublic.h"
+
+#ifdef NIGHTLY_BUILD
+// For performance reasons, we make the JS Dev Error Interceptor a Nightly-only
+// feature.
+# define MOZ_JS_DEV_ERROR_INTERCEPTOR = 1
+#endif // NIGHTLY_BUILD
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+namespace mozilla {
+
+struct DeferredFinalizeFunctionHolder {
+ DeferredFinalizeFunction run;
+ void* data;
+};
+
+class IncrementalFinalizeRunnable : public DiscardableRunnable {
+ typedef AutoTArray<DeferredFinalizeFunctionHolder, 16> DeferredFinalizeArray;
+ typedef CycleCollectedJSRuntime::DeferredFinalizerTable
+ DeferredFinalizerTable;
+
+ CycleCollectedJSRuntime* mRuntime;
+ DeferredFinalizeArray mDeferredFinalizeFunctions;
+ uint32_t mFinalizeFunctionToRun;
+ bool mReleasing;
+
+ static const PRTime SliceMillis = 5; /* ms */
+
+ public:
+ IncrementalFinalizeRunnable(CycleCollectedJSRuntime* aRt,
+ DeferredFinalizerTable& aFinalizerTable);
+ virtual ~IncrementalFinalizeRunnable();
+
+ void ReleaseNow(bool aLimited);
+
+ NS_DECL_NSIRUNNABLE
+};
+
+} // namespace mozilla
+
+struct NoteWeakMapChildrenTracer : public JS::CallbackTracer {
+ NoteWeakMapChildrenTracer(JSRuntime* aRt,
+ nsCycleCollectionNoteRootCallback& aCb)
+ : JS::CallbackTracer(aRt, JS::TracerKind::Callback),
+ mCb(aCb),
+ mTracedAny(false),
+ mMap(nullptr),
+ mKey(nullptr),
+ mKeyDelegate(nullptr) {}
+ void onChild(JS::GCCellPtr aThing, const char* name) override;
+ nsCycleCollectionNoteRootCallback& mCb;
+ bool mTracedAny;
+ JSObject* mMap;
+ JS::GCCellPtr mKey;
+ JSObject* mKeyDelegate;
+};
+
+void NoteWeakMapChildrenTracer::onChild(JS::GCCellPtr aThing,
+ const char* name) {
+ if (aThing.is<JSString>()) {
+ return;
+ }
+
+ if (!JS::GCThingIsMarkedGrayInCC(aThing) && !mCb.WantAllTraces()) {
+ return;
+ }
+
+ if (JS::IsCCTraceKind(aThing.kind())) {
+ mCb.NoteWeakMapping(mMap, mKey, mKeyDelegate, aThing);
+ mTracedAny = true;
+ } else {
+ JS::TraceChildren(this, aThing);
+ }
+}
+
+struct NoteWeakMapsTracer : public js::WeakMapTracer {
+ NoteWeakMapsTracer(JSRuntime* aRt, nsCycleCollectionNoteRootCallback& aCccb)
+ : js::WeakMapTracer(aRt), mCb(aCccb), mChildTracer(aRt, aCccb) {}
+ void trace(JSObject* aMap, JS::GCCellPtr aKey, JS::GCCellPtr aValue) override;
+ nsCycleCollectionNoteRootCallback& mCb;
+ NoteWeakMapChildrenTracer mChildTracer;
+};
+
+void NoteWeakMapsTracer::trace(JSObject* aMap, JS::GCCellPtr aKey,
+ JS::GCCellPtr aValue) {
+ // If nothing that could be held alive by this entry is marked gray, return.
+ if ((!aKey || !JS::GCThingIsMarkedGrayInCC(aKey)) &&
+ MOZ_LIKELY(!mCb.WantAllTraces())) {
+ if (!aValue || !JS::GCThingIsMarkedGrayInCC(aValue) ||
+ aValue.is<JSString>()) {
+ return;
+ }
+ }
+
+ // The cycle collector can only properly reason about weak maps if it can
+ // reason about the liveness of their keys, which in turn requires that
+ // the key can be represented in the cycle collector graph. All existing
+ // uses of weak maps use either objects or scripts as keys, which are okay.
+ MOZ_ASSERT(JS::IsCCTraceKind(aKey.kind()));
+
+ // As an emergency fallback for non-debug builds, if the key is not
+ // representable in the cycle collector graph, we treat it as marked. This
+ // can cause leaks, but is preferable to ignoring the binding, which could
+ // cause the cycle collector to free live objects.
+ if (!JS::IsCCTraceKind(aKey.kind())) {
+ aKey = nullptr;
+ }
+
+ JSObject* kdelegate = nullptr;
+ if (aKey.is<JSObject>()) {
+ kdelegate = js::UncheckedUnwrapWithoutExpose(&aKey.as<JSObject>());
+ }
+
+ if (JS::IsCCTraceKind(aValue.kind())) {
+ mCb.NoteWeakMapping(aMap, aKey, kdelegate, aValue);
+ } else {
+ mChildTracer.mTracedAny = false;
+ mChildTracer.mMap = aMap;
+ mChildTracer.mKey = aKey;
+ mChildTracer.mKeyDelegate = kdelegate;
+
+ if (!aValue.is<JSString>()) {
+ JS::TraceChildren(&mChildTracer, aValue);
+ }
+
+ // The delegate could hold alive the key, so report something to the CC
+ // if we haven't already.
+ if (!mChildTracer.mTracedAny && aKey && JS::GCThingIsMarkedGrayInCC(aKey) &&
+ kdelegate) {
+ mCb.NoteWeakMapping(aMap, aKey, kdelegate, nullptr);
+ }
+ }
+}
+
+// Report whether the key or value of a weak mapping entry are gray but need to
+// be marked black.
+static void ShouldWeakMappingEntryBeBlack(JSObject* aMap, JS::GCCellPtr aKey,
+ JS::GCCellPtr aValue,
+ bool* aKeyShouldBeBlack,
+ bool* aValueShouldBeBlack) {
+ *aKeyShouldBeBlack = false;
+ *aValueShouldBeBlack = false;
+
+ // If nothing that could be held alive by this entry is marked gray, return.
+ bool keyMightNeedMarking = aKey && JS::GCThingIsMarkedGrayInCC(aKey);
+ bool valueMightNeedMarking = aValue && JS::GCThingIsMarkedGrayInCC(aValue) &&
+ aValue.kind() != JS::TraceKind::String;
+ if (!keyMightNeedMarking && !valueMightNeedMarking) {
+ return;
+ }
+
+ if (!JS::IsCCTraceKind(aKey.kind())) {
+ aKey = nullptr;
+ }
+
+ if (keyMightNeedMarking && aKey.is<JSObject>()) {
+ JSObject* kdelegate =
+ js::UncheckedUnwrapWithoutExpose(&aKey.as<JSObject>());
+ if (kdelegate && !JS::ObjectIsMarkedGray(kdelegate) &&
+ (!aMap || !JS::ObjectIsMarkedGray(aMap))) {
+ *aKeyShouldBeBlack = true;
+ }
+ }
+
+ if (aValue && JS::GCThingIsMarkedGrayInCC(aValue) &&
+ (!aKey || !JS::GCThingIsMarkedGrayInCC(aKey)) &&
+ (!aMap || !JS::ObjectIsMarkedGray(aMap)) &&
+ aValue.kind() != JS::TraceKind::Shape) {
+ *aValueShouldBeBlack = true;
+ }
+}
+
+struct FixWeakMappingGrayBitsTracer : public js::WeakMapTracer {
+ explicit FixWeakMappingGrayBitsTracer(JSRuntime* aRt)
+ : js::WeakMapTracer(aRt) {}
+
+ void FixAll() {
+ do {
+ mAnyMarked = false;
+ js::TraceWeakMaps(this);
+ } while (mAnyMarked);
+ }
+
+ void trace(JSObject* aMap, JS::GCCellPtr aKey,
+ JS::GCCellPtr aValue) override {
+ bool keyShouldBeBlack;
+ bool valueShouldBeBlack;
+ ShouldWeakMappingEntryBeBlack(aMap, aKey, aValue, &keyShouldBeBlack,
+ &valueShouldBeBlack);
+ if (keyShouldBeBlack && JS::UnmarkGrayGCThingRecursively(aKey)) {
+ mAnyMarked = true;
+ }
+
+ if (valueShouldBeBlack && JS::UnmarkGrayGCThingRecursively(aValue)) {
+ mAnyMarked = true;
+ }
+ }
+
+ MOZ_INIT_OUTSIDE_CTOR bool mAnyMarked;
+};
+
+#ifdef DEBUG
+// Check whether weak maps are marked correctly according to the logic above.
+struct CheckWeakMappingGrayBitsTracer : public js::WeakMapTracer {
+ explicit CheckWeakMappingGrayBitsTracer(JSRuntime* aRt)
+ : js::WeakMapTracer(aRt), mFailed(false) {}
+
+ static bool Check(JSRuntime* aRt) {
+ CheckWeakMappingGrayBitsTracer tracer(aRt);
+ js::TraceWeakMaps(&tracer);
+ return !tracer.mFailed;
+ }
+
+ void trace(JSObject* aMap, JS::GCCellPtr aKey,
+ JS::GCCellPtr aValue) override {
+ bool keyShouldBeBlack;
+ bool valueShouldBeBlack;
+ ShouldWeakMappingEntryBeBlack(aMap, aKey, aValue, &keyShouldBeBlack,
+ &valueShouldBeBlack);
+
+ if (keyShouldBeBlack) {
+ fprintf(stderr, "Weak mapping key %p of map %p should be black\n",
+ aKey.asCell(), aMap);
+ mFailed = true;
+ }
+
+ if (valueShouldBeBlack) {
+ fprintf(stderr, "Weak mapping value %p of map %p should be black\n",
+ aValue.asCell(), aMap);
+ mFailed = true;
+ }
+ }
+
+ bool mFailed;
+};
+#endif // DEBUG
+
+static void CheckParticipatesInCycleCollection(JS::GCCellPtr aThing,
+ const char* aName,
+ void* aClosure) {
+ bool* cycleCollectionEnabled = static_cast<bool*>(aClosure);
+
+ if (*cycleCollectionEnabled) {
+ return;
+ }
+
+ if (JS::IsCCTraceKind(aThing.kind()) && JS::GCThingIsMarkedGrayInCC(aThing)) {
+ *cycleCollectionEnabled = true;
+ }
+}
+
+NS_IMETHODIMP
+JSGCThingParticipant::TraverseNative(void* aPtr,
+ nsCycleCollectionTraversalCallback& aCb) {
+ auto runtime = reinterpret_cast<CycleCollectedJSRuntime*>(
+ reinterpret_cast<char*>(this) -
+ offsetof(CycleCollectedJSRuntime, mGCThingCycleCollectorGlobal));
+
+ JS::GCCellPtr cellPtr(aPtr, JS::GCThingTraceKind(aPtr));
+ runtime->TraverseGCThing(CycleCollectedJSRuntime::TRAVERSE_FULL, cellPtr,
+ aCb);
+ return NS_OK;
+}
+
+// NB: This is only used to initialize the participant in
+// CycleCollectedJSRuntime. It should never be used directly.
+static JSGCThingParticipant sGCThingCycleCollectorGlobal;
+
+NS_IMETHODIMP
+JSZoneParticipant::TraverseNative(void* aPtr,
+ nsCycleCollectionTraversalCallback& aCb) {
+ auto runtime = reinterpret_cast<CycleCollectedJSRuntime*>(
+ reinterpret_cast<char*>(this) -
+ offsetof(CycleCollectedJSRuntime, mJSZoneCycleCollectorGlobal));
+
+ MOZ_ASSERT(!aCb.WantAllTraces());
+ JS::Zone* zone = static_cast<JS::Zone*>(aPtr);
+
+ runtime->TraverseZone(zone, aCb);
+ return NS_OK;
+}
+
+struct TraversalTracer : public JS::CallbackTracer {
+ TraversalTracer(JSRuntime* aRt, nsCycleCollectionTraversalCallback& aCb)
+ : JS::CallbackTracer(aRt, JS::TracerKind::Callback,
+ JS::TraceOptions(JS::WeakMapTraceAction::Skip,
+ JS::WeakEdgeTraceAction::Trace)),
+ mCb(aCb) {}
+ void onChild(JS::GCCellPtr aThing, const char* name) override;
+ nsCycleCollectionTraversalCallback& mCb;
+};
+
+void TraversalTracer::onChild(JS::GCCellPtr aThing, const char* name) {
+ // Checking strings and symbols for being gray is rather slow, and we don't
+ // need either of them for the cycle collector.
+ if (aThing.is<JSString>() || aThing.is<JS::Symbol>()) {
+ return;
+ }
+
+ // Don't traverse non-gray objects, unless we want all traces.
+ if (!JS::GCThingIsMarkedGrayInCC(aThing) && !mCb.WantAllTraces()) {
+ return;
+ }
+
+ /*
+ * This function needs to be careful to avoid stack overflow. Normally, when
+ * IsCCTraceKind is true, the recursion terminates immediately as we just add
+ * |thing| to the CC graph. So overflow is only possible when there are long
+ * or cyclic chains of non-IsCCTraceKind GC things. Places where this can
+ * occur use special APIs to handle such chains iteratively.
+ */
+ if (JS::IsCCTraceKind(aThing.kind())) {
+ if (MOZ_UNLIKELY(mCb.WantDebugInfo())) {
+ char buffer[200];
+ context().getEdgeName(name, buffer, sizeof(buffer));
+ mCb.NoteNextEdgeName(buffer);
+ }
+ mCb.NoteJSChild(aThing);
+ return;
+ }
+
+ // Allow re-use of this tracer inside trace callback.
+ JS::AutoClearTracingContext actc(this);
+
+ if (aThing.is<js::Shape>()) {
+ // The maximum depth of traversal when tracing a Shape is unbounded, due to
+ // the parent pointers on the shape.
+ JS_TraceShapeCycleCollectorChildren(this, aThing);
+ } else {
+ JS::TraceChildren(this, aThing);
+ }
+}
+
+/*
+ * The cycle collection participant for a Zone is intended to produce the same
+ * results as if all of the gray GCthings in a zone were merged into a single
+ * node, except for self-edges. This avoids the overhead of representing all of
+ * the GCthings in the zone in the cycle collector graph, which should be much
+ * faster if many of the GCthings in the zone are gray.
+ *
+ * Zone merging should not always be used, because it is a conservative
+ * approximation of the true cycle collector graph that can incorrectly identify
+ * some garbage objects as being live. For instance, consider two cycles that
+ * pass through a zone, where one is garbage and the other is live. If we merge
+ * the entire zone, the cycle collector will think that both are alive.
+ *
+ * We don't have to worry about losing track of a garbage cycle, because any
+ * such garbage cycle incorrectly identified as live must contain at least one
+ * C++ to JS edge, and XPConnect will always add the C++ object to the CC graph.
+ * (This is in contrast to pure C++ garbage cycles, which must always be
+ * properly identified, because we clear the purple buffer during every CC,
+ * which may contain the last reference to a garbage cycle.)
+ */
+
+// NB: This is only used to initialize the participant in
+// CycleCollectedJSRuntime. It should never be used directly.
+static const JSZoneParticipant sJSZoneCycleCollectorGlobal;
+
+static void JSObjectsTenuredCb(JSContext* aContext, void* aData) {
+ static_cast<CycleCollectedJSRuntime*>(aData)->JSObjectsTenured();
+}
+
+static void MozCrashWarningReporter(JSContext*, JSErrorReport*) {
+ MOZ_CRASH("Why is someone touching JSAPI without an AutoJSAPI?");
+}
+
+JSHolderMap::Entry::Entry() : Entry(nullptr, nullptr, nullptr) {}
+
+JSHolderMap::Entry::Entry(void* aHolder, nsScriptObjectTracer* aTracer,
+ JS::Zone* aZone)
+ : mHolder(aHolder),
+ mTracer(aTracer)
+#ifdef DEBUG
+ ,
+ mZone(aZone)
+#endif
+{
+}
+
+void JSHolderMap::EntryVectorIter::Settle() {
+ if (Done()) {
+ return;
+ }
+
+ Entry* entry = &mIter.Get();
+
+ // If the entry has been cleared, remove it and shrink the vector.
+ if (!entry->mHolder && !mHolderMap.RemoveEntry(mVector, entry)) {
+ // We removed the last entry, so reset the iterator to an empty one.
+ mIter = EntryVector().Iter();
+ MOZ_ASSERT(Done());
+ }
+}
+
+JSHolderMap::Iter::Iter(JSHolderMap& aMap, WhichHolders aWhich)
+ : mHolderMap(aMap), mIter(aMap, aMap.mAnyZoneJSHolders) {
+ MOZ_RELEASE_ASSERT(!mHolderMap.mHasIterator);
+ mHolderMap.mHasIterator = true;
+
+ // Populate vector of zones to iterate after the any-zone holders.
+ for (auto i = aMap.mPerZoneJSHolders.iter(); !i.done(); i.next()) {
+ JS::Zone* zone = i.get().key();
+ if (aWhich == AllHolders || JS::NeedGrayRootsForZone(i.get().key())) {
+ MOZ_ALWAYS_TRUE(mZones.append(zone));
+ }
+ }
+
+ Settle();
+}
+
+void JSHolderMap::Iter::Settle() {
+ while (mIter.Done()) {
+ if (mZone && mIter.Vector().IsEmpty()) {
+ mHolderMap.mPerZoneJSHolders.remove(mZone);
+ }
+
+ mZone = nullptr;
+ if (mZones.empty()) {
+ break;
+ }
+
+ mZone = mZones.popCopy();
+ EntryVector& vector = *mHolderMap.mPerZoneJSHolders.lookup(mZone)->value();
+ new (&mIter) EntryVectorIter(mHolderMap, vector);
+ }
+}
+
+void JSHolderMap::Iter::UpdateForRemovals() {
+ mIter.Settle();
+ Settle();
+}
+
+JSHolderMap::JSHolderMap() : mJSHolderMap(256) {}
+
+bool JSHolderMap::RemoveEntry(EntryVector& aJSHolders, Entry* aEntry) {
+ MOZ_ASSERT(aEntry);
+ MOZ_ASSERT(!aEntry->mHolder);
+
+ // Remove all dead entries from the end of the vector.
+ while (!aJSHolders.GetLast().mHolder && &aJSHolders.GetLast() != aEntry) {
+ aJSHolders.PopLast();
+ }
+
+ // Swap the element we want to remove with the last one and update the hash
+ // table.
+ Entry* lastEntry = &aJSHolders.GetLast();
+ if (aEntry != lastEntry) {
+ MOZ_ASSERT(lastEntry->mHolder);
+ *aEntry = *lastEntry;
+ MOZ_ASSERT(mJSHolderMap.has(aEntry->mHolder));
+ MOZ_ALWAYS_TRUE(mJSHolderMap.put(aEntry->mHolder, aEntry));
+ }
+
+ aJSHolders.PopLast();
+
+ // Return whether aEntry is still in the vector.
+ return aEntry != lastEntry;
+}
+
+bool JSHolderMap::Has(void* aHolder) const { return mJSHolderMap.has(aHolder); }
+
+nsScriptObjectTracer* JSHolderMap::Get(void* aHolder) const {
+ auto ptr = mJSHolderMap.lookup(aHolder);
+ if (!ptr) {
+ return nullptr;
+ }
+
+ Entry* entry = ptr->value();
+ MOZ_ASSERT(entry->mHolder == aHolder);
+ return entry->mTracer;
+}
+
+nsScriptObjectTracer* JSHolderMap::Extract(void* aHolder) {
+ MOZ_ASSERT(aHolder);
+
+ auto ptr = mJSHolderMap.lookup(aHolder);
+ if (!ptr) {
+ return nullptr;
+ }
+
+ Entry* entry = ptr->value();
+ MOZ_ASSERT(entry->mHolder == aHolder);
+ nsScriptObjectTracer* tracer = entry->mTracer;
+
+ // Clear the entry's contents. It will be removed the next time iteration
+ // visits this entry.
+ *entry = Entry();
+
+ mJSHolderMap.remove(ptr);
+
+ return tracer;
+}
+
+void JSHolderMap::Put(void* aHolder, nsScriptObjectTracer* aTracer,
+ JS::Zone* aZone) {
+ MOZ_ASSERT(aHolder);
+ MOZ_ASSERT(aTracer);
+
+ // Don't associate multi-zone holders with a zone, even if one is supplied.
+ if (!aTracer->IsSingleZoneJSHolder()) {
+ aZone = nullptr;
+ }
+
+ auto ptr = mJSHolderMap.lookupForAdd(aHolder);
+ if (ptr) {
+ Entry* entry = ptr->value();
+#ifdef DEBUG
+ MOZ_ASSERT(entry->mHolder == aHolder);
+ MOZ_ASSERT(entry->mTracer == aTracer,
+ "Don't call HoldJSObjects in superclass ctors");
+ if (aZone) {
+ if (entry->mZone) {
+ MOZ_ASSERT(entry->mZone == aZone);
+ } else {
+ entry->mZone = aZone;
+ }
+ }
+#endif
+ entry->mTracer = aTracer;
+ return;
+ }
+
+ EntryVector* vector = &mAnyZoneJSHolders;
+ if (aZone) {
+ auto ptr = mPerZoneJSHolders.lookupForAdd(aZone);
+ if (!ptr) {
+ MOZ_ALWAYS_TRUE(
+ mPerZoneJSHolders.add(ptr, aZone, MakeUnique<EntryVector>()));
+ }
+ vector = ptr->value().get();
+ }
+
+ vector->InfallibleAppend(Entry{aHolder, aTracer, aZone});
+ MOZ_ALWAYS_TRUE(mJSHolderMap.add(ptr, aHolder, &vector->GetLast()));
+}
+
+size_t JSHolderMap::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+ size_t n = 0;
+
+ // We're deliberately not measuring anything hanging off the entries in
+ // mJSHolders.
+ n += mJSHolderMap.shallowSizeOfExcludingThis(aMallocSizeOf);
+ n += mAnyZoneJSHolders.SizeOfExcludingThis(aMallocSizeOf);
+ n += mPerZoneJSHolders.shallowSizeOfExcludingThis(aMallocSizeOf);
+ for (auto i = mPerZoneJSHolders.iter(); !i.done(); i.next()) {
+ n += i.get().value()->SizeOfExcludingThis(aMallocSizeOf);
+ }
+
+ return n;
+}
+
+static bool InitializeShadowRealm(JSContext* aCx,
+ JS::Handle<JSObject*> aGlobal) {
+ MOZ_ASSERT(StaticPrefs::javascript_options_experimental_shadow_realms());
+
+ JSAutoRealm ar(aCx, aGlobal);
+ return dom::RegisterShadowRealmBindings(aCx, aGlobal);
+}
+
+CycleCollectedJSRuntime::CycleCollectedJSRuntime(JSContext* aCx)
+ : mContext(nullptr),
+ mGCThingCycleCollectorGlobal(sGCThingCycleCollectorGlobal),
+ mJSZoneCycleCollectorGlobal(sJSZoneCycleCollectorGlobal),
+ mJSRuntime(JS_GetRuntime(aCx)),
+ mHasPendingIdleGCTask(false),
+ mPrevGCSliceCallback(nullptr),
+ mOutOfMemoryState(OOMState::OK),
+ mLargeAllocationFailureState(OOMState::OK)
+#ifdef DEBUG
+ ,
+ mShutdownCalled(false)
+#endif
+{
+ MOZ_COUNT_CTOR(CycleCollectedJSRuntime);
+ MOZ_ASSERT(aCx);
+ MOZ_ASSERT(mJSRuntime);
+
+#if defined(XP_MACOSX)
+ if (!XRE_IsParentProcess()) {
+ nsMacUtilsImpl::EnableTCSMIfAvailable();
+ }
+#endif
+
+ if (!JS_AddExtraGCRootsTracer(aCx, TraceBlackJS, this)) {
+ MOZ_CRASH("JS_AddExtraGCRootsTracer failed");
+ }
+ JS_SetGrayGCRootsTracer(aCx, TraceGrayJS, this);
+ JS_SetGCCallback(aCx, GCCallback, this);
+ mPrevGCSliceCallback = JS::SetGCSliceCallback(aCx, GCSliceCallback);
+
+ if (NS_IsMainThread()) {
+ // We would like to support all threads here, but the way timeline consumers
+ // are set up currently, you can either add a marker for one specific
+ // docshell, or for every consumer globally. We would like to add a marker
+ // for every consumer observing anything on this thread, but that is not
+ // currently possible. For now, add global markers only when we are on the
+ // main thread, since the UI for this tracing data only displays data
+ // relevant to the main-thread.
+ JS::AddGCNurseryCollectionCallback(aCx, GCNurseryCollectionCallback,
+ nullptr);
+ }
+
+ JS_SetObjectsTenuredCallback(aCx, JSObjectsTenuredCb, this);
+ JS::SetOutOfMemoryCallback(aCx, OutOfMemoryCallback, this);
+ JS::SetWaitCallback(mJSRuntime, BeforeWaitCallback, AfterWaitCallback,
+ sizeof(dom::AutoYieldJSThreadExecution));
+ JS::SetWarningReporter(aCx, MozCrashWarningReporter);
+ JS::SetShadowRealmInitializeGlobalCallback(aCx, InitializeShadowRealm);
+ JS::SetShadowRealmGlobalCreationCallback(aCx, dom::NewShadowRealmGlobal);
+
+ js::AutoEnterOOMUnsafeRegion::setAnnotateOOMAllocationSizeCallback(
+ CrashReporter::AnnotateOOMAllocationSize);
+
+ static js::DOMCallbacks DOMcallbacks = {InstanceClassHasProtoAtDepth};
+ SetDOMCallbacks(aCx, &DOMcallbacks);
+ js::SetScriptEnvironmentPreparer(aCx, &mEnvironmentPreparer);
+
+ JS::dbg::SetDebuggerMallocSizeOf(aCx, moz_malloc_size_of);
+
+#ifdef MOZ_JS_DEV_ERROR_INTERCEPTOR
+ JS_SetErrorInterceptorCallback(mJSRuntime, &mErrorInterceptor);
+#endif // MOZ_JS_DEV_ERROR_INTERCEPTOR
+
+ JS_SetDestroyZoneCallback(aCx, OnZoneDestroyed);
+}
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+class JSLeakTracer : public JS::CallbackTracer {
+ public:
+ explicit JSLeakTracer(JSRuntime* aRuntime)
+ : JS::CallbackTracer(aRuntime, JS::TracerKind::Callback,
+ JS::WeakMapTraceAction::TraceKeysAndValues) {}
+
+ private:
+ void onChild(JS::GCCellPtr thing, const char* name) override {
+ const char* kindName = JS::GCTraceKindToAscii(thing.kind());
+ size_t size = JS::GCTraceKindSize(thing.kind());
+ MOZ_LOG_CTOR(thing.asCell(), kindName, size);
+ }
+};
+#endif
+
+void CycleCollectedJSRuntime::Shutdown(JSContext* aCx) {
+#ifdef MOZ_JS_DEV_ERROR_INTERCEPTOR
+ mErrorInterceptor.Shutdown(mJSRuntime);
+#endif // MOZ_JS_DEV_ERROR_INTERCEPTOR
+
+ // There should not be any roots left to trace at this point. Ensure any that
+ // remain are flagged as leaks.
+#ifdef NS_BUILD_REFCNT_LOGGING
+ JSLeakTracer tracer(Runtime());
+ TraceNativeBlackRoots(&tracer);
+ TraceAllNativeGrayRoots(&tracer);
+#endif
+
+#ifdef DEBUG
+ mShutdownCalled = true;
+#endif
+
+ JS_SetDestroyZoneCallback(aCx, nullptr);
+
+ if (NS_IsMainThread()) {
+ JS::RemoveGCNurseryCollectionCallback(aCx, GCNurseryCollectionCallback,
+ nullptr);
+ }
+}
+
+CycleCollectedJSRuntime::~CycleCollectedJSRuntime() {
+ MOZ_COUNT_DTOR(CycleCollectedJSRuntime);
+ MOZ_ASSERT(!mDeferredFinalizerTable.Count());
+ MOZ_ASSERT(!mFinalizeRunnable);
+ MOZ_ASSERT(mShutdownCalled);
+}
+
+void CycleCollectedJSRuntime::SetContext(CycleCollectedJSContext* aContext) {
+ MOZ_ASSERT(!mContext || !aContext, "Don't replace the context!");
+ mContext = aContext;
+}
+
+size_t CycleCollectedJSRuntime::SizeOfExcludingThis(
+ MallocSizeOf aMallocSizeOf) const {
+ return mJSHolders.SizeOfExcludingThis(aMallocSizeOf);
+}
+
+void CycleCollectedJSRuntime::UnmarkSkippableJSHolders() {
+ for (JSHolderMap::Iter entry(mJSHolders); !entry.Done(); entry.Next()) {
+ entry->mTracer->CanSkip(entry->mHolder, true);
+ }
+}
+
+void CycleCollectedJSRuntime::DescribeGCThing(
+ bool aIsMarked, JS::GCCellPtr aThing,
+ nsCycleCollectionTraversalCallback& aCb) const {
+ if (!aCb.WantDebugInfo()) {
+ aCb.DescribeGCedNode(aIsMarked, "JS Object");
+ return;
+ }
+
+ char name[72];
+ uint64_t compartmentAddress = 0;
+ if (aThing.is<JSObject>()) {
+ JSObject* obj = &aThing.as<JSObject>();
+ compartmentAddress = (uint64_t)JS::GetCompartment(obj);
+ const JSClass* clasp = JS::GetClass(obj);
+
+ // Give the subclass a chance to do something
+ if (DescribeCustomObjects(obj, clasp, name)) {
+ // Nothing else to do!
+ } else if (js::IsFunctionObject(obj)) {
+ JSFunction* fun = JS_GetObjectFunction(obj);
+ JSString* str = JS_GetMaybePartialFunctionDisplayId(fun);
+ if (str) {
+ JSLinearString* linear = JS_ASSERT_STRING_IS_LINEAR(str);
+ nsAutoString chars;
+ AssignJSLinearString(chars, linear);
+ NS_ConvertUTF16toUTF8 fname(chars);
+ SprintfLiteral(name, "JS Object (Function - %s)", fname.get());
+ } else {
+ SprintfLiteral(name, "JS Object (Function)");
+ }
+ } else {
+ SprintfLiteral(name, "JS Object (%s)", clasp->name);
+ }
+ } else {
+ SprintfLiteral(name, "%s", JS::GCTraceKindToAscii(aThing.kind()));
+ }
+
+ // Disable printing global for objects while we figure out ObjShrink fallout.
+ aCb.DescribeGCedNode(aIsMarked, name, compartmentAddress);
+}
+
+void CycleCollectedJSRuntime::NoteGCThingJSChildren(
+ JS::GCCellPtr aThing, nsCycleCollectionTraversalCallback& aCb) const {
+ TraversalTracer trc(mJSRuntime, aCb);
+ JS::TraceChildren(&trc, aThing);
+}
+
+void CycleCollectedJSRuntime::NoteGCThingXPCOMChildren(
+ const JSClass* aClasp, JSObject* aObj,
+ nsCycleCollectionTraversalCallback& aCb) const {
+ MOZ_ASSERT(aClasp);
+ MOZ_ASSERT(aClasp == JS::GetClass(aObj));
+
+ JS::Rooted<JSObject*> obj(RootingCx(), aObj);
+
+ if (NoteCustomGCThingXPCOMChildren(aClasp, obj, aCb)) {
+ // Nothing else to do!
+ return;
+ }
+
+ // XXX This test does seem fragile, we should probably allowlist classes
+ // that do hold a strong reference, but that might not be possible.
+ if (aClasp->slot0IsISupports()) {
+ NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "JS::GetObjectISupports(obj)");
+ aCb.NoteXPCOMChild(JS::GetObjectISupports<nsISupports>(obj));
+ return;
+ }
+
+ const DOMJSClass* domClass = GetDOMClass(aClasp);
+ if (domClass) {
+ NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "UnwrapDOMObject(obj)");
+ // It's possible that our object is an unforgeable holder object, in
+ // which case it doesn't actually have a C++ DOM object associated with
+ // it. Use UnwrapPossiblyNotInitializedDOMObject, which produces null in
+ // that case, since NoteXPCOMChild/NoteNativeChild are null-safe.
+ if (domClass->mDOMObjectIsISupports) {
+ aCb.NoteXPCOMChild(
+ UnwrapPossiblyNotInitializedDOMObject<nsISupports>(obj));
+ } else if (domClass->mParticipant) {
+ aCb.NoteNativeChild(UnwrapPossiblyNotInitializedDOMObject<void>(obj),
+ domClass->mParticipant);
+ }
+ return;
+ }
+
+ if (IsRemoteObjectProxy(obj)) {
+ auto handler =
+ static_cast<const RemoteObjectProxyBase*>(js::GetProxyHandler(obj));
+ return handler->NoteChildren(obj, aCb);
+ }
+
+ JS::Value value = js::MaybeGetScriptPrivate(obj);
+ if (!value.isUndefined()) {
+ aCb.NoteXPCOMChild(static_cast<nsISupports*>(value.toPrivate()));
+ }
+}
+
+void CycleCollectedJSRuntime::TraverseGCThing(
+ TraverseSelect aTs, JS::GCCellPtr aThing,
+ nsCycleCollectionTraversalCallback& aCb) {
+ bool isMarkedGray = JS::GCThingIsMarkedGrayInCC(aThing);
+
+ if (aTs == TRAVERSE_FULL) {
+ DescribeGCThing(!isMarkedGray, aThing, aCb);
+ }
+
+ // If this object is alive, then all of its children are alive. For JS
+ // objects, the black-gray invariant ensures the children are also marked
+ // black. For C++ objects, the ref count from this object will keep them
+ // alive. Thus we don't need to trace our children, unless we are debugging
+ // using WantAllTraces.
+ if (!isMarkedGray && !aCb.WantAllTraces()) {
+ return;
+ }
+
+ if (aTs == TRAVERSE_FULL) {
+ NoteGCThingJSChildren(aThing, aCb);
+ }
+
+ if (aThing.is<JSObject>()) {
+ JSObject* obj = &aThing.as<JSObject>();
+ NoteGCThingXPCOMChildren(JS::GetClass(obj), obj, aCb);
+ }
+}
+
+struct TraverseObjectShimClosure {
+ nsCycleCollectionTraversalCallback& cb;
+ CycleCollectedJSRuntime* self;
+};
+
+void CycleCollectedJSRuntime::TraverseZone(
+ JS::Zone* aZone, nsCycleCollectionTraversalCallback& aCb) {
+ /*
+ * We treat the zone as being gray. We handle non-gray GCthings in the
+ * zone by not reporting their children to the CC. The black-gray invariant
+ * ensures that any JS children will also be non-gray, and thus don't need to
+ * be added to the graph. For C++ children, not representing the edge from the
+ * non-gray JS GCthings to the C++ object will keep the child alive.
+ *
+ * We don't allow zone merging in a WantAllTraces CC, because then these
+ * assumptions don't hold.
+ */
+ aCb.DescribeGCedNode(false, "JS Zone");
+
+ /*
+ * Every JS child of everything in the zone is either in the zone
+ * or is a cross-compartment wrapper. In the former case, we don't need to
+ * represent these edges in the CC graph because JS objects are not ref
+ * counted. In the latter case, the JS engine keeps a map of these wrappers,
+ * which we iterate over. Edges between compartments in the same zone will add
+ * unnecessary loop edges to the graph (bug 842137).
+ */
+ TraversalTracer trc(mJSRuntime, aCb);
+ js::TraceGrayWrapperTargets(&trc, aZone);
+
+ /*
+ * To find C++ children of things in the zone, we scan every JS Object in
+ * the zone. Only JS Objects can have C++ children.
+ */
+ TraverseObjectShimClosure closure = {aCb, this};
+ js::IterateGrayObjects(aZone, TraverseObjectShim, &closure);
+}
+
+/* static */
+void CycleCollectedJSRuntime::TraverseObjectShim(
+ void* aData, JS::GCCellPtr aThing, const JS::AutoRequireNoGC& nogc) {
+ TraverseObjectShimClosure* closure =
+ static_cast<TraverseObjectShimClosure*>(aData);
+
+ MOZ_ASSERT(aThing.is<JSObject>());
+ closure->self->TraverseGCThing(CycleCollectedJSRuntime::TRAVERSE_CPP, aThing,
+ closure->cb);
+}
+
+void CycleCollectedJSRuntime::TraverseNativeRoots(
+ nsCycleCollectionNoteRootCallback& aCb) {
+ // NB: This is here just to preserve the existing XPConnect order. I doubt it
+ // would hurt to do this after the JS holders.
+ TraverseAdditionalNativeRoots(aCb);
+
+ for (JSHolderMap::Iter entry(mJSHolders); !entry.Done(); entry.Next()) {
+ void* holder = entry->mHolder;
+ nsScriptObjectTracer* tracer = entry->mTracer;
+
+ bool noteRoot = false;
+ if (MOZ_UNLIKELY(aCb.WantAllTraces())) {
+ noteRoot = true;
+ } else {
+ tracer->Trace(holder,
+ TraceCallbackFunc(CheckParticipatesInCycleCollection),
+ &noteRoot);
+ }
+
+ if (noteRoot) {
+ aCb.NoteNativeRoot(holder, tracer);
+ }
+ }
+}
+
+/* static */
+void CycleCollectedJSRuntime::TraceBlackJS(JSTracer* aTracer, void* aData) {
+ CycleCollectedJSRuntime* self = static_cast<CycleCollectedJSRuntime*>(aData);
+
+ self->TraceNativeBlackRoots(aTracer);
+}
+
+/* static */
+bool CycleCollectedJSRuntime::TraceGrayJS(JSTracer* aTracer,
+ js::SliceBudget& budget,
+ void* aData) {
+ CycleCollectedJSRuntime* self = static_cast<CycleCollectedJSRuntime*>(aData);
+
+ // Mark these roots as gray so the CC can walk them later.
+
+ JSHolderMap::WhichHolders which = JSHolderMap::AllHolders;
+
+ // Only trace holders in collecting zones when marking, except if we are
+ // collecting the atoms zone since any holder may point into that zone.
+ if (aTracer->isMarkingTracer() &&
+ !JS::AtomsZoneIsCollecting(self->Runtime())) {
+ which = JSHolderMap::HoldersRequiredForGrayMarking;
+ }
+
+ return self->TraceNativeGrayRoots(aTracer, which, budget);
+}
+
+/* static */
+void CycleCollectedJSRuntime::GCCallback(JSContext* aContext,
+ JSGCStatus aStatus,
+ JS::GCReason aReason, void* aData) {
+ CycleCollectedJSRuntime* self = static_cast<CycleCollectedJSRuntime*>(aData);
+
+ MOZ_ASSERT(CycleCollectedJSContext::Get()->Context() == aContext);
+ MOZ_ASSERT(CycleCollectedJSContext::Get()->Runtime() == self);
+
+ self->OnGC(aContext, aStatus, aReason);
+}
+
+struct GCMajorMarker : public BaseMarkerType<GCMajorMarker> {
+ static constexpr const char* Name = "GCMajor";
+ static constexpr const char* Description =
+ "Summary data for an entire major GC, encompassing a set of "
+ "incremental slices. The main thread is not blocked for the "
+ "entire major GC interval, only for the individual slices.";
+
+ using MS = MarkerSchema;
+ static constexpr MS::PayloadField PayloadFields[] = {
+ {"timings", MS::InputType::String, "GC timings"}};
+
+ static constexpr MS::Location Locations[] = {MS::Location::MarkerChart,
+ MS::Location::MarkerTable,
+ MS::Location::TimelineMemory};
+ static constexpr MS::ETWMarkerGroup Group = MS::ETWMarkerGroup::Memory;
+
+ static void StreamJSONMarkerData(
+ mozilla::baseprofiler::SpliceableJSONWriter& aWriter,
+ const mozilla::ProfilerString8View& aTimingJSON) {
+ if (aTimingJSON.Length() != 0) {
+ aWriter.SplicedJSONProperty("timings", aTimingJSON);
+ } else {
+ aWriter.NullProperty("timings");
+ }
+ }
+};
+
+/* static */
+void CycleCollectedJSRuntime::GCSliceCallback(JSContext* aContext,
+ JS::GCProgress aProgress,
+ const JS::GCDescription& aDesc) {
+ CycleCollectedJSRuntime* self = CycleCollectedJSRuntime::Get();
+ MOZ_ASSERT(CycleCollectedJSContext::Get()->Context() == aContext);
+
+ if (profiler_thread_is_being_profiled_for_markers()) {
+ if (aProgress == JS::GC_CYCLE_END) {
+ profiler_add_marker("GCMajor", baseprofiler::category::GCCC,
+ MarkerTiming::Interval(aDesc.startTime(aContext),
+ aDesc.endTime(aContext)),
+ GCMajorMarker{},
+ ProfilerString8View::WrapNullTerminatedString(
+ aDesc.formatJSONProfiler(aContext).get()));
+ } else if (aProgress == JS::GC_SLICE_END) {
+ struct GCSliceMarker {
+ static constexpr mozilla::Span<const char> MarkerTypeName() {
+ return mozilla::MakeStringSpan("GCSlice");
+ }
+ static void StreamJSONMarkerData(
+ mozilla::baseprofiler::SpliceableJSONWriter& aWriter,
+ const mozilla::ProfilerString8View& aTimingJSON) {
+ if (aTimingJSON.Length() != 0) {
+ aWriter.SplicedJSONProperty("timings", aTimingJSON);
+ } else {
+ aWriter.NullProperty("timings");
+ }
+ }
+ static mozilla::MarkerSchema MarkerTypeDisplay() {
+ using MS = mozilla::MarkerSchema;
+ MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable,
+ MS::Location::TimelineMemory};
+ schema.AddStaticLabelValue(
+ "Description",
+ "One slice of an incremental garbage collection (GC). The main "
+ "thread is blocked during this time.");
+ // No display instructions here, there is special handling in the
+ // front-end.
+ return schema;
+ }
+ };
+
+ profiler_add_marker("GCSlice", baseprofiler::category::GCCC,
+ MarkerTiming::Interval(aDesc.lastSliceStart(aContext),
+ aDesc.lastSliceEnd(aContext)),
+ GCSliceMarker{},
+ ProfilerString8View::WrapNullTerminatedString(
+ aDesc.sliceToJSONProfiler(aContext).get()));
+ }
+ }
+
+ if (aProgress == JS::GC_CYCLE_END &&
+ JS::dbg::FireOnGarbageCollectionHookRequired(aContext)) {
+ JS::GCReason reason = aDesc.reason_;
+ Unused << NS_WARN_IF(
+ NS_FAILED(DebuggerOnGCRunnable::Enqueue(aContext, aDesc)) &&
+ reason != JS::GCReason::SHUTDOWN_CC &&
+ reason != JS::GCReason::DESTROY_RUNTIME &&
+ reason != JS::GCReason::XPCONNECT_SHUTDOWN);
+ }
+
+ if (self->mPrevGCSliceCallback) {
+ self->mPrevGCSliceCallback(aContext, aProgress, aDesc);
+ }
+}
+
+/* static */
+void CycleCollectedJSRuntime::GCNurseryCollectionCallback(
+ JSContext* aContext, JS::GCNurseryProgress aProgress, JS::GCReason aReason,
+ void* data) {
+ CycleCollectedJSRuntime* self = CycleCollectedJSRuntime::Get();
+ MOZ_ASSERT(CycleCollectedJSContext::Get()->Context() == aContext);
+ MOZ_ASSERT(NS_IsMainThread());
+
+ TimeStamp now = TimeStamp::Now();
+ if (aProgress == JS::GCNurseryProgress::GC_NURSERY_COLLECTION_START) {
+ self->mLatestNurseryCollectionStart = now;
+ } else if (aProgress == JS::GCNurseryProgress::GC_NURSERY_COLLECTION_END) {
+ PerfStats::RecordMeasurement(PerfStats::Metric::MinorGC,
+ now - self->mLatestNurseryCollectionStart);
+ }
+
+ if (aProgress == JS::GCNurseryProgress::GC_NURSERY_COLLECTION_END &&
+ profiler_thread_is_being_profiled_for_markers()) {
+ struct GCMinorMarker {
+ static constexpr mozilla::Span<const char> MarkerTypeName() {
+ return mozilla::MakeStringSpan("GCMinor");
+ }
+ static void StreamJSONMarkerData(
+ mozilla::baseprofiler::SpliceableJSONWriter& aWriter,
+ const mozilla::ProfilerString8View& aTimingJSON) {
+ if (aTimingJSON.Length() != 0) {
+ aWriter.SplicedJSONProperty("nursery", aTimingJSON);
+ } else {
+ aWriter.NullProperty("nursery");
+ }
+ }
+ static mozilla::MarkerSchema MarkerTypeDisplay() {
+ using MS = mozilla::MarkerSchema;
+ MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable,
+ MS::Location::TimelineMemory};
+ schema.AddStaticLabelValue(
+ "Description",
+ "A minor GC (aka nursery collection) to clear out the buffer used "
+ "for recent allocations and move surviving data to the tenured "
+ "(long-lived) heap.");
+ // No display instructions here, there is special handling in the
+ // front-end.
+ return schema;
+ }
+ };
+
+ profiler_add_marker(
+ "GCMinor", baseprofiler::category::GCCC,
+ MarkerTiming::Interval(self->mLatestNurseryCollectionStart, now),
+ GCMinorMarker{},
+ ProfilerString8View::WrapNullTerminatedString(
+ JS::MinorGcToJSON(aContext).get()));
+ }
+}
+
+/* static */
+void CycleCollectedJSRuntime::OutOfMemoryCallback(JSContext* aContext,
+ void* aData) {
+ CycleCollectedJSRuntime* self = static_cast<CycleCollectedJSRuntime*>(aData);
+
+ MOZ_ASSERT(CycleCollectedJSContext::Get()->Context() == aContext);
+ MOZ_ASSERT(CycleCollectedJSContext::Get()->Runtime() == self);
+
+ self->OnOutOfMemory();
+}
+
+/* static */
+void* CycleCollectedJSRuntime::BeforeWaitCallback(uint8_t* aMemory) {
+ MOZ_ASSERT(aMemory);
+
+ // aMemory is stack allocated memory to contain our RAII object. This allows
+ // for us to avoid allocations on the heap during this callback.
+ return new (aMemory) dom::AutoYieldJSThreadExecution;
+}
+
+/* static */
+void CycleCollectedJSRuntime::AfterWaitCallback(void* aCookie) {
+ MOZ_ASSERT(aCookie);
+ static_cast<dom::AutoYieldJSThreadExecution*>(aCookie)
+ ->~AutoYieldJSThreadExecution();
+}
+
+struct JsGcTracer : public TraceCallbacks {
+ virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+ virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+ virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+ virtual void Trace(nsWrapperCache* aPtr, const char* aName,
+ void* aClosure) const override {
+ aPtr->TraceWrapper(static_cast<JSTracer*>(aClosure), aName);
+ }
+ virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+ virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+ virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+ virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+ }
+};
+
+void mozilla::TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer) {
+ nsXPCOMCycleCollectionParticipant* participant = nullptr;
+ CallQueryInterface(aHolder, &participant);
+ participant->Trace(aHolder, JsGcTracer(), aTracer);
+}
+
+#if defined(NIGHTLY_BUILD) || defined(MOZ_DEV_EDITION) || defined(DEBUG)
+# define CHECK_SINGLE_ZONE_JS_HOLDERS
+#endif
+
+#ifdef CHECK_SINGLE_ZONE_JS_HOLDERS
+
+// A tracer that checks that a JS holder only holds JS GC things in a single
+// JS::Zone.
+struct CheckZoneTracer : public TraceCallbacks {
+ const char* mClassName;
+ mutable JS::Zone* mZone;
+
+ explicit CheckZoneTracer(const char* aClassName, JS::Zone* aZone = nullptr)
+ : mClassName(aClassName), mZone(aZone) {}
+
+ void checkZone(JS::Zone* aZone, const char* aName) const {
+ if (JS::IsAtomsZone(aZone)) {
+ // Any holder may contain pointers into the atoms zone.
+ return;
+ }
+
+ if (!mZone) {
+ mZone = aZone;
+ return;
+ }
+
+ if (aZone == mZone) {
+ return;
+ }
+
+ // Most JS holders only contain pointers to GC things in a single zone. We
+ // group holders by referent zone where possible, allowing us to improve GC
+ // performance by only tracing holders for zones that are being collected.
+ //
+ // Additionally, pointers from any holder into the atoms zone are allowed
+ // since all holders are traced when we collect the atoms zone.
+ //
+ // If you added a holder that has pointers into multiple zones do not
+ // use NS_IMPL_CYCLE_COLLECTION_SINGLE_ZONE_SCRIPT_HOLDER_CLASS.
+ MOZ_CRASH_UNSAFE_PRINTF(
+ "JS holder %s contains pointers to GC things in more than one zone ("
+ "found in %s)\n",
+ mClassName, aName);
+ }
+
+ virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JS::Value value = aPtr->unbarrieredGet();
+ if (value.isGCThing()) {
+ checkZone(JS::GetGCThingZone(value.toGCCellPtr()), aName);
+ }
+ }
+ virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+ void* aClosure) const override {
+ jsid id = aPtr->unbarrieredGet();
+ if (id.isGCThing()) {
+ MOZ_ASSERT(JS::IsAtomsZone(JS::GetTenuredGCThingZone(id.toGCCellPtr())));
+ }
+ }
+ virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JSObject* obj = aPtr->unbarrieredGet();
+ if (obj) {
+ checkZone(js::GetObjectZoneFromAnyThread(obj), aName);
+ }
+ }
+ virtual void Trace(nsWrapperCache* aPtr, const char* aName,
+ void* aClosure) const override {
+ JSObject* obj = aPtr->GetWrapperPreserveColor();
+ if (obj) {
+ checkZone(js::GetObjectZoneFromAnyThread(obj), aName);
+ }
+ }
+ virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JSObject* obj = aPtr->unbarrieredGetPtr();
+ if (obj) {
+ checkZone(js::GetObjectZoneFromAnyThread(obj), aName);
+ }
+ }
+ virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JSString* str = aPtr->unbarrieredGet();
+ if (str) {
+ checkZone(JS::GetStringZone(str), aName);
+ }
+ }
+ virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JSScript* script = aPtr->unbarrieredGet();
+ if (script) {
+ checkZone(JS::GetTenuredGCThingZone(JS::GCCellPtr(script)), aName);
+ }
+ }
+ virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+ void* aClosure) const override {
+ JSFunction* fun = aPtr->unbarrieredGet();
+ if (fun) {
+ checkZone(js::GetObjectZoneFromAnyThread(JS_GetFunctionObject(fun)),
+ aName);
+ }
+ }
+};
+
+static inline void CheckHolderIsSingleZone(
+ void* aHolder, nsCycleCollectionParticipant* aParticipant,
+ JS::Zone* aZone) {
+ CheckZoneTracer tracer(aParticipant->ClassName(), aZone);
+ aParticipant->Trace(aHolder, tracer, nullptr);
+}
+
+#endif
+
+static inline bool ShouldCheckSingleZoneHolders() {
+#if defined(DEBUG)
+ return true;
+#elif defined(NIGHTLY_BUILD) || defined(MOZ_DEV_EDITION)
+ // Don't check every time to avoid performance impact.
+ return rand() % 256 == 0;
+#else
+ return false;
+#endif
+}
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+void CycleCollectedJSRuntime::TraceAllNativeGrayRoots(JSTracer* aTracer) {
+ MOZ_RELEASE_ASSERT(mHolderIter.isNothing());
+ js::SliceBudget budget = js::SliceBudget::unlimited();
+ MOZ_ALWAYS_TRUE(
+ TraceNativeGrayRoots(aTracer, JSHolderMap::AllHolders, budget));
+}
+#endif
+
+bool CycleCollectedJSRuntime::TraceNativeGrayRoots(
+ JSTracer* aTracer, JSHolderMap::WhichHolders aWhich,
+ js::SliceBudget& aBudget) {
+ if (!mHolderIter) {
+ // NB: This is here just to preserve the existing XPConnect order. I doubt
+ // it would hurt to do this after the JS holders.
+ TraceAdditionalNativeGrayRoots(aTracer);
+
+ mHolderIter.emplace(mJSHolders, aWhich);
+ aBudget.forceCheck();
+ } else {
+ // Holders may have been removed between slices, so we may need to update
+ // the iterator.
+ mHolderIter->UpdateForRemovals();
+ }
+
+ bool finished = TraceJSHolders(aTracer, *mHolderIter, aBudget);
+ if (finished) {
+ mHolderIter.reset();
+ }
+
+ return finished;
+}
+
+bool CycleCollectedJSRuntime::TraceJSHolders(JSTracer* aTracer,
+ JSHolderMap::Iter& aIter,
+ js::SliceBudget& aBudget) {
+ bool checkSingleZoneHolders = ShouldCheckSingleZoneHolders();
+
+ while (!aIter.Done() && !aBudget.isOverBudget()) {
+ void* holder = aIter->mHolder;
+ nsScriptObjectTracer* tracer = aIter->mTracer;
+
+#ifdef CHECK_SINGLE_ZONE_JS_HOLDERS
+ if (checkSingleZoneHolders && tracer->IsSingleZoneJSHolder()) {
+ CheckHolderIsSingleZone(holder, tracer, aIter.Zone());
+ }
+#else
+ Unused << checkSingleZoneHolders;
+#endif
+
+ tracer->Trace(holder, JsGcTracer(), aTracer);
+
+ aIter.Next();
+ aBudget.step();
+ }
+
+ return aIter.Done();
+}
+
+void CycleCollectedJSRuntime::AddJSHolder(void* aHolder,
+ nsScriptObjectTracer* aTracer,
+ JS::Zone* aZone) {
+ mJSHolders.Put(aHolder, aTracer, aZone);
+}
+
+struct ClearJSHolder : public TraceCallbacks {
+ virtual void Trace(JS::Heap<JS::Value>* aPtr, const char*,
+ void*) const override {
+ aPtr->setUndefined();
+ }
+
+ virtual void Trace(JS::Heap<jsid>* aPtr, const char*, void*) const override {
+ *aPtr = JS::PropertyKey::Void();
+ }
+
+ virtual void Trace(JS::Heap<JSObject*>* aPtr, const char*,
+ void*) const override {
+ *aPtr = nullptr;
+ }
+
+ virtual void Trace(nsWrapperCache* aPtr, const char* aName,
+ void* aClosure) const override {
+ aPtr->ClearWrapper();
+ }
+
+ virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char*,
+ void*) const override {
+ *aPtr = nullptr;
+ }
+
+ virtual void Trace(JS::Heap<JSString*>* aPtr, const char*,
+ void*) const override {
+ *aPtr = nullptr;
+ }
+
+ virtual void Trace(JS::Heap<JSScript*>* aPtr, const char*,
+ void*) const override {
+ *aPtr = nullptr;
+ }
+
+ virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char*,
+ void*) const override {
+ *aPtr = nullptr;
+ }
+};
+
+void CycleCollectedJSRuntime::RemoveJSHolder(void* aHolder) {
+ nsScriptObjectTracer* tracer = mJSHolders.Extract(aHolder);
+ if (tracer) {
+ // Bug 1531951: The analysis can't see through the virtual call but we know
+ // that the ClearJSHolder tracer will never GC.
+ JS::AutoSuppressGCAnalysis nogc;
+ tracer->Trace(aHolder, ClearJSHolder(), nullptr);
+ }
+}
+
+#ifdef DEBUG
+static void AssertNoGcThing(JS::GCCellPtr aGCThing, const char* aName,
+ void* aClosure) {
+ MOZ_ASSERT(!aGCThing);
+}
+
+void CycleCollectedJSRuntime::AssertNoObjectsToTrace(void* aPossibleJSHolder) {
+ nsScriptObjectTracer* tracer = mJSHolders.Get(aPossibleJSHolder);
+ if (tracer) {
+ tracer->Trace(aPossibleJSHolder, TraceCallbackFunc(AssertNoGcThing),
+ nullptr);
+ }
+}
+#endif
+
+nsCycleCollectionParticipant* CycleCollectedJSRuntime::GCThingParticipant() {
+ return &mGCThingCycleCollectorGlobal;
+}
+
+nsCycleCollectionParticipant* CycleCollectedJSRuntime::ZoneParticipant() {
+ return &mJSZoneCycleCollectorGlobal;
+}
+
+nsresult CycleCollectedJSRuntime::TraverseRoots(
+ nsCycleCollectionNoteRootCallback& aCb) {
+ TraverseNativeRoots(aCb);
+
+ NoteWeakMapsTracer trc(mJSRuntime, aCb);
+ js::TraceWeakMaps(&trc);
+
+ return NS_OK;
+}
+
+bool CycleCollectedJSRuntime::UsefulToMergeZones() const { return false; }
+
+void CycleCollectedJSRuntime::FixWeakMappingGrayBits() const {
+ MOZ_ASSERT(!JS::IsIncrementalGCInProgress(mJSRuntime),
+ "Don't call FixWeakMappingGrayBits during a GC.");
+ FixWeakMappingGrayBitsTracer fixer(mJSRuntime);
+ fixer.FixAll();
+}
+
+void CycleCollectedJSRuntime::CheckGrayBits() const {
+ MOZ_ASSERT(!JS::IsIncrementalGCInProgress(mJSRuntime),
+ "Don't call CheckGrayBits during a GC.");
+
+#ifndef ANDROID
+ // Bug 1346874 - The gray state check is expensive. Android tests are already
+ // slow enough that this check can easily push them over the threshold to a
+ // timeout.
+
+ MOZ_ASSERT(js::CheckGrayMarkingState(mJSRuntime));
+ MOZ_ASSERT(CheckWeakMappingGrayBitsTracer::Check(mJSRuntime));
+#endif
+}
+
+bool CycleCollectedJSRuntime::AreGCGrayBitsValid() const {
+ return js::AreGCGrayBitsValid(mJSRuntime);
+}
+
+void CycleCollectedJSRuntime::GarbageCollect(JS::GCOptions aOptions,
+ JS::GCReason aReason) const {
+ JSContext* cx = CycleCollectedJSContext::Get()->Context();
+ JS::PrepareForFullGC(cx);
+ JS::NonIncrementalGC(cx, aOptions, aReason);
+}
+
+void CycleCollectedJSRuntime::JSObjectsTenured() {
+ JSContext* cx = CycleCollectedJSContext::Get()->Context();
+ for (auto iter = mNurseryObjects.Iter(); !iter.Done(); iter.Next()) {
+ nsWrapperCache* cache = iter.Get();
+ JSObject* wrapper = cache->GetWrapperMaybeDead();
+ MOZ_DIAGNOSTIC_ASSERT(wrapper);
+ if (!JS::ObjectIsTenured(wrapper)) {
+ MOZ_ASSERT(!cache->PreservingWrapper());
+ js::gc::FinalizeDeadNurseryObject(cx, wrapper);
+ }
+ }
+
+ mNurseryObjects.Clear();
+}
+
+void CycleCollectedJSRuntime::NurseryWrapperAdded(nsWrapperCache* aCache) {
+ MOZ_ASSERT(aCache);
+ MOZ_ASSERT(aCache->GetWrapperMaybeDead());
+ MOZ_ASSERT(!JS::ObjectIsTenured(aCache->GetWrapperMaybeDead()));
+ mNurseryObjects.InfallibleAppend(aCache);
+}
+
+void CycleCollectedJSRuntime::DeferredFinalize(
+ DeferredFinalizeAppendFunction aAppendFunc, DeferredFinalizeFunction aFunc,
+ void* aThing) {
+ // Tell the analysis that the function pointers will not GC.
+ JS::AutoSuppressGCAnalysis suppress;
+ mDeferredFinalizerTable.WithEntryHandle(aFunc, [&](auto&& entry) {
+ if (entry) {
+ aAppendFunc(entry.Data(), aThing);
+ } else {
+ entry.Insert(aAppendFunc(nullptr, aThing));
+ }
+ });
+}
+
+void CycleCollectedJSRuntime::DeferredFinalize(nsISupports* aSupports) {
+ typedef DeferredFinalizerImpl<nsISupports> Impl;
+ DeferredFinalize(Impl::AppendDeferredFinalizePointer, Impl::DeferredFinalize,
+ aSupports);
+}
+
+void CycleCollectedJSRuntime::DumpJSHeap(FILE* aFile) {
+ JSContext* cx = CycleCollectedJSContext::Get()->Context();
+
+ mozilla::MallocSizeOf mallocSizeOf =
+ PR_GetEnv("MOZ_GC_LOG_SIZE") ? moz_malloc_size_of : nullptr;
+ js::DumpHeap(cx, aFile, js::CollectNurseryBeforeDump, mallocSizeOf);
+}
+
+IncrementalFinalizeRunnable::IncrementalFinalizeRunnable(
+ CycleCollectedJSRuntime* aRt, DeferredFinalizerTable& aFinalizers)
+ : DiscardableRunnable("IncrementalFinalizeRunnable"),
+ mRuntime(aRt),
+ mFinalizeFunctionToRun(0),
+ mReleasing(false) {
+ for (auto iter = aFinalizers.Iter(); !iter.Done(); iter.Next()) {
+ DeferredFinalizeFunction& function = iter.Key();
+ void*& data = iter.Data();
+
+ DeferredFinalizeFunctionHolder* holder =
+ mDeferredFinalizeFunctions.AppendElement();
+ holder->run = function;
+ holder->data = data;
+
+ iter.Remove();
+ }
+ MOZ_ASSERT(mDeferredFinalizeFunctions.Length());
+}
+
+IncrementalFinalizeRunnable::~IncrementalFinalizeRunnable() {
+ MOZ_ASSERT(!mDeferredFinalizeFunctions.Length());
+ MOZ_ASSERT(!mRuntime);
+}
+
+void IncrementalFinalizeRunnable::ReleaseNow(bool aLimited) {
+ if (mReleasing) {
+ NS_WARNING("Re-entering ReleaseNow");
+ return;
+ }
+ {
+ AUTO_PROFILER_LABEL("IncrementalFinalizeRunnable::ReleaseNow",
+ GCCC_Finalize);
+
+ mozilla::AutoRestore<bool> ar(mReleasing);
+ mReleasing = true;
+ MOZ_ASSERT(mDeferredFinalizeFunctions.Length() != 0,
+ "We should have at least ReleaseSliceNow to run");
+ MOZ_ASSERT(mFinalizeFunctionToRun < mDeferredFinalizeFunctions.Length(),
+ "No more finalizers to run?");
+
+ TimeDuration sliceTime = TimeDuration::FromMilliseconds(SliceMillis);
+ TimeStamp started = aLimited ? TimeStamp::Now() : TimeStamp();
+ bool timeout = false;
+ do {
+ const DeferredFinalizeFunctionHolder& function =
+ mDeferredFinalizeFunctions[mFinalizeFunctionToRun];
+ if (aLimited) {
+ bool done = false;
+ while (!timeout && !done) {
+ /*
+ * We don't want to read the clock too often, so we try to
+ * release slices of 100 items.
+ */
+ done = function.run(100, function.data);
+ timeout = TimeStamp::Now() - started >= sliceTime;
+ }
+ if (done) {
+ ++mFinalizeFunctionToRun;
+ }
+ if (timeout) {
+ break;
+ }
+ } else {
+ while (!function.run(UINT32_MAX, function.data))
+ ;
+ ++mFinalizeFunctionToRun;
+ }
+ } while (mFinalizeFunctionToRun < mDeferredFinalizeFunctions.Length());
+ }
+
+ if (mFinalizeFunctionToRun == mDeferredFinalizeFunctions.Length()) {
+ MOZ_ASSERT(mRuntime->mFinalizeRunnable == this);
+ mDeferredFinalizeFunctions.Clear();
+ CycleCollectedJSRuntime* runtime = mRuntime;
+ mRuntime = nullptr;
+ // NB: This may delete this!
+ runtime->mFinalizeRunnable = nullptr;
+ }
+}
+
+NS_IMETHODIMP
+IncrementalFinalizeRunnable::Run() {
+ if (!mDeferredFinalizeFunctions.Length()) {
+ /* These items were already processed synchronously in JSGC_END. */
+ MOZ_ASSERT(!mRuntime);
+ return NS_OK;
+ }
+
+ MOZ_ASSERT(mRuntime->mFinalizeRunnable == this);
+ TimeStamp start = TimeStamp::Now();
+ ReleaseNow(true);
+
+ if (mDeferredFinalizeFunctions.Length()) {
+ nsresult rv = NS_DispatchToCurrentThread(this);
+ if (NS_FAILED(rv)) {
+ ReleaseNow(false);
+ }
+ } else {
+ MOZ_ASSERT(!mRuntime);
+ }
+
+ uint32_t duration = (uint32_t)((TimeStamp::Now() - start).ToMilliseconds());
+ Telemetry::Accumulate(Telemetry::DEFERRED_FINALIZE_ASYNC, duration);
+
+ return NS_OK;
+}
+
+void CycleCollectedJSRuntime::FinalizeDeferredThings(
+ DeferredFinalizeType aType) {
+ // If mFinalizeRunnable isn't null, we didn't finalize everything from the
+ // previous GC.
+ if (mFinalizeRunnable) {
+ if (aType == FinalizeLater) {
+ // We need to defer all finalization until we return to the event loop,
+ // so leave things alone. Any new objects to be finalized from the current
+ // GC will be handled by the existing mFinalizeRunnable.
+ return;
+ }
+ MOZ_ASSERT(aType == FinalizeIncrementally || aType == FinalizeNow);
+ // If we're finalizing incrementally, we don't want finalizers to build up,
+ // so try to finish them off now.
+ // If we're finalizing synchronously, also go ahead and clear them out,
+ // so we make sure as much as possible is freed.
+ mFinalizeRunnable->ReleaseNow(false);
+ if (mFinalizeRunnable) {
+ // If we re-entered ReleaseNow, we couldn't delete mFinalizeRunnable and
+ // we need to just continue processing it.
+ return;
+ }
+ }
+
+ // If there's nothing to finalize, don't create a new runnable.
+ if (mDeferredFinalizerTable.Count() == 0) {
+ return;
+ }
+
+ mFinalizeRunnable =
+ new IncrementalFinalizeRunnable(this, mDeferredFinalizerTable);
+
+ // Everything should be gone now.
+ MOZ_ASSERT(mDeferredFinalizerTable.Count() == 0);
+
+ if (aType == FinalizeNow) {
+ mFinalizeRunnable->ReleaseNow(false);
+ MOZ_ASSERT(!mFinalizeRunnable);
+ } else {
+ MOZ_ASSERT(aType == FinalizeIncrementally || aType == FinalizeLater);
+ NS_DispatchToCurrentThreadQueue(do_AddRef(mFinalizeRunnable), 2500,
+ EventQueuePriority::Idle);
+ }
+}
+
+const char* CycleCollectedJSRuntime::OOMStateToString(
+ const OOMState aOomState) const {
+ switch (aOomState) {
+ case OOMState::OK:
+ return "OK";
+ case OOMState::Reporting:
+ return "Reporting";
+ case OOMState::Reported:
+ return "Reported";
+ case OOMState::Recovered:
+ return "Recovered";
+ default:
+ MOZ_ASSERT_UNREACHABLE("OOMState holds an invalid value");
+ return "Unknown";
+ }
+}
+
+bool CycleCollectedJSRuntime::OOMReported() {
+ return mOutOfMemoryState == OOMState::Reported;
+}
+
+void CycleCollectedJSRuntime::AnnotateAndSetOutOfMemory(OOMState* aStatePtr,
+ OOMState aNewState) {
+ *aStatePtr = aNewState;
+ CrashReporter::Annotation annotation =
+ (aStatePtr == &mOutOfMemoryState)
+ ? CrashReporter::Annotation::JSOutOfMemory
+ : CrashReporter::Annotation::JSLargeAllocationFailure;
+
+ CrashReporter::AnnotateCrashReport(
+ annotation, nsDependentCString(OOMStateToString(aNewState)));
+}
+
+void CycleCollectedJSRuntime::OnGC(JSContext* aContext, JSGCStatus aStatus,
+ JS::GCReason aReason) {
+ switch (aStatus) {
+ case JSGC_BEGIN:
+ MOZ_RELEASE_ASSERT(mHolderIter.isNothing());
+ nsCycleCollector_prepareForGarbageCollection();
+ PrepareWaitingZonesForGC();
+ break;
+ case JSGC_END: {
+ MOZ_RELEASE_ASSERT(mHolderIter.isNothing());
+ if (mOutOfMemoryState == OOMState::Reported) {
+ AnnotateAndSetOutOfMemory(&mOutOfMemoryState, OOMState::Recovered);
+ }
+ if (mLargeAllocationFailureState == OOMState::Reported) {
+ AnnotateAndSetOutOfMemory(&mLargeAllocationFailureState,
+ OOMState::Recovered);
+ }
+
+ DeferredFinalizeType finalizeType;
+ if (JS_IsExceptionPending(aContext)) {
+ // There is a pending exception. The finalizers are not set up to run
+ // in that state, so don't run the finalizer until we've returned to the
+ // event loop.
+ finalizeType = FinalizeLater;
+ } else if (JS::InternalGCReason(aReason)) {
+ if (aReason == JS::GCReason::DESTROY_RUNTIME) {
+ // We're shutting down, so we need to destroy things immediately.
+ finalizeType = FinalizeNow;
+ } else {
+ // We may be in the middle of running some code that the JIT has
+ // assumed can't have certain kinds of side effects. Finalizers can do
+ // all sorts of things, such as run JS, so we want to run them later,
+ // after we've returned to the event loop.
+ finalizeType = FinalizeLater;
+ }
+ } else if (JS::WasIncrementalGC(mJSRuntime)) {
+ // The GC was incremental, so we probably care about pauses. Try to
+ // break up finalization, but it is okay if we do some now.
+ finalizeType = FinalizeIncrementally;
+ } else {
+ // If we're running a synchronous GC, we probably want to free things as
+ // quickly as possible. This can happen during testing or if memory is
+ // low.
+ finalizeType = FinalizeNow;
+ }
+ FinalizeDeferredThings(finalizeType);
+
+ break;
+ }
+ default:
+ MOZ_CRASH();
+ }
+
+ CustomGCCallback(aStatus);
+}
+
+void CycleCollectedJSRuntime::OnOutOfMemory() {
+ AnnotateAndSetOutOfMemory(&mOutOfMemoryState, OOMState::Reporting);
+ CustomOutOfMemoryCallback();
+ AnnotateAndSetOutOfMemory(&mOutOfMemoryState, OOMState::Reported);
+}
+
+void CycleCollectedJSRuntime::SetLargeAllocationFailure(OOMState aNewState) {
+ AnnotateAndSetOutOfMemory(&mLargeAllocationFailureState, aNewState);
+}
+
+void CycleCollectedJSRuntime::PrepareWaitingZonesForGC() {
+ JSContext* cx = CycleCollectedJSContext::Get()->Context();
+ if (mZonesWaitingForGC.Count() == 0) {
+ JS::PrepareForFullGC(cx);
+ } else {
+ for (const auto& key : mZonesWaitingForGC) {
+ JS::PrepareZoneForGC(cx, key);
+ }
+ mZonesWaitingForGC.Clear();
+ }
+}
+
+/* static */
+void CycleCollectedJSRuntime::OnZoneDestroyed(JS::GCContext* aGcx,
+ JS::Zone* aZone) {
+ // Remove the zone from the set of zones waiting for GC, if present. This can
+ // happen if a zone is added to the set during an incremental GC in which it
+ // is later destroyed.
+ CycleCollectedJSRuntime* runtime = Get();
+ runtime->mZonesWaitingForGC.Remove(aZone);
+}
+
+void CycleCollectedJSRuntime::EnvironmentPreparer::invoke(
+ JS::HandleObject global, js::ScriptEnvironmentPreparer::Closure& closure) {
+ MOZ_ASSERT(JS_IsGlobalObject(global));
+ nsIGlobalObject* nativeGlobal = xpc::NativeGlobal(global);
+
+ // Not much we can do if we simply don't have a usable global here...
+ NS_ENSURE_TRUE_VOID(nativeGlobal && nativeGlobal->HasJSGlobal());
+
+ AutoEntryScript aes(nativeGlobal, "JS-engine-initiated execution");
+
+ MOZ_ASSERT(!JS_IsExceptionPending(aes.cx()));
+
+ DebugOnly<bool> ok = closure(aes.cx());
+
+ MOZ_ASSERT_IF(ok, !JS_IsExceptionPending(aes.cx()));
+
+ // The AutoEntryScript will check for JS_IsExceptionPending on the
+ // JSContext and report it as needed as it comes off the stack.
+}
+
+/* static */
+CycleCollectedJSRuntime* CycleCollectedJSRuntime::Get() {
+ auto context = CycleCollectedJSContext::Get();
+ if (context) {
+ return context->Runtime();
+ }
+ return nullptr;
+}
+
+#ifdef MOZ_JS_DEV_ERROR_INTERCEPTOR
+
+namespace js {
+extern void DumpValue(const JS::Value& val);
+}
+
+void CycleCollectedJSRuntime::ErrorInterceptor::Shutdown(JSRuntime* rt) {
+ JS_SetErrorInterceptorCallback(rt, nullptr);
+ mThrownError.reset();
+}
+
+/* virtual */
+void CycleCollectedJSRuntime::ErrorInterceptor::interceptError(
+ JSContext* cx, JS::HandleValue exn) {
+ if (mThrownError) {
+ // We already have an error, we don't need anything more.
+ return;
+ }
+
+ if (!nsContentUtils::ThreadsafeIsSystemCaller(cx)) {
+ // We are only interested in chrome code.
+ return;
+ }
+
+ const auto type = JS_GetErrorType(exn);
+ if (!type) {
+ // This is not one of the primitive error types.
+ return;
+ }
+
+ switch (*type) {
+ case JSExnType::JSEXN_REFERENCEERR:
+ case JSExnType::JSEXN_SYNTAXERR:
+ break;
+ default:
+ // Not one of the errors we are interested in.
+ // Note that we are not interested in instances of `TypeError`
+ // for the time being, as DOM (ab)uses this constructor to represent
+ // all sorts of errors that are not even remotely related to type
+ // errors (e.g. some network errors).
+ // If we ever have a mechanism to differentiate between DOM-thrown
+ // and SpiderMonkey-thrown instances of `TypeError`, we should
+ // consider watching for `TypeError` here.
+ return;
+ }
+
+ // Now copy the details of the exception locally.
+ // While copying the details of an exception could be expensive, in most runs,
+ // this will be done at most once during the execution of the process, so the
+ // total cost should be reasonable.
+
+ ErrorDetails details;
+ details.mType = *type;
+ // If `exn` isn't an exception object, `ExtractErrorValues` could end up
+ // calling `toString()`, which could in turn end up throwing an error. While
+ // this should work, we want to avoid that complex use case. Fortunately, we
+ // have already checked above that `exn` is an exception object, so nothing
+ // such should happen.
+ nsContentUtils::ExtractErrorValues(cx, exn, details.mFilename, &details.mLine,
+ &details.mColumn, details.mMessage);
+
+ JS::UniqueChars buf =
+ JS::FormatStackDump(cx, /* showArgs = */ false, /* showLocals = */ false,
+ /* showThisProps = */ false);
+ CopyUTF8toUTF16(mozilla::MakeStringSpan(buf.get()), details.mStack);
+
+ mThrownError.emplace(std::move(details));
+}
+
+void CycleCollectedJSRuntime::ClearRecentDevError() {
+ mErrorInterceptor.mThrownError.reset();
+}
+
+bool CycleCollectedJSRuntime::GetRecentDevError(
+ JSContext* cx, JS::MutableHandle<JS::Value> error) {
+ if (!mErrorInterceptor.mThrownError) {
+ return true;
+ }
+
+ // Create a copy of the exception.
+ JS::RootedObject obj(cx, JS_NewPlainObject(cx));
+ if (!obj) {
+ return false;
+ }
+
+ JS::RootedValue message(cx);
+ JS::RootedValue filename(cx);
+ JS::RootedValue stack(cx);
+ if (!ToJSValue(cx, mErrorInterceptor.mThrownError->mMessage, &message) ||
+ !ToJSValue(cx, mErrorInterceptor.mThrownError->mFilename, &filename) ||
+ !ToJSValue(cx, mErrorInterceptor.mThrownError->mStack, &stack)) {
+ return false;
+ }
+
+ // Build the object.
+ const auto FLAGS = JSPROP_READONLY | JSPROP_ENUMERATE | JSPROP_PERMANENT;
+ if (!JS_DefineProperty(cx, obj, "message", message, FLAGS) ||
+ !JS_DefineProperty(cx, obj, "fileName", filename, FLAGS) ||
+ !JS_DefineProperty(cx, obj, "lineNumber",
+ mErrorInterceptor.mThrownError->mLine, FLAGS) ||
+ !JS_DefineProperty(cx, obj, "stack", stack, FLAGS)) {
+ return false;
+ }
+
+ // Pass the result.
+ error.setObject(*obj);
+ return true;
+}
+#endif // MOZ_JS_DEV_ERROR_INTERCEPTOR
+
+#undef MOZ_JS_DEV_ERROR_INTERCEPTOR