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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/. */
+
+#ifndef gc_GCRuntime_h
+#define gc_GCRuntime_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/DoublyLinkedList.h"
+#include "mozilla/EnumSet.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/TimeStamp.h"
+
+#include "gc/ArenaList.h"
+#include "gc/AtomMarking.h"
+#include "gc/GCContext.h"
+#include "gc/GCMarker.h"
+#include "gc/GCParallelTask.h"
+#include "gc/IteratorUtils.h"
+#include "gc/Nursery.h"
+#include "gc/Scheduling.h"
+#include "gc/Statistics.h"
+#include "gc/StoreBuffer.h"
+#include "js/friend/PerformanceHint.h"
+#include "js/GCAnnotations.h"
+#include "js/UniquePtr.h"
+#include "vm/AtomsTable.h"
+
+namespace js {
+
+class AutoLockGC;
+class AutoLockGCBgAlloc;
+class AutoLockHelperThreadState;
+class FinalizationRegistryObject;
+class FinalizationRecordObject;
+class FinalizationQueueObject;
+class GlobalObject;
+class VerifyPreTracer;
+class WeakRefObject;
+
+namespace gc {
+
+using BlackGrayEdgeVector = Vector<TenuredCell*, 0, SystemAllocPolicy>;
+using ZoneVector = Vector<JS::Zone*, 4, SystemAllocPolicy>;
+
+class AutoCallGCCallbacks;
+class AutoGCSession;
+class AutoHeapSession;
+class AutoTraceSession;
+struct FinalizePhase;
+class MarkingValidator;
+struct MovingTracer;
+class ParallelMarkTask;
+enum class ShouldCheckThresholds;
+class SweepGroupsIter;
+
+// Interface to a sweep action.
+struct SweepAction {
+ // The arguments passed to each action.
+ struct Args {
+ GCRuntime* gc;
+ JS::GCContext* gcx;
+ SliceBudget& budget;
+ };
+
+ virtual ~SweepAction() = default;
+ virtual IncrementalProgress run(Args& state) = 0;
+ virtual void assertFinished() const = 0;
+ virtual bool shouldSkip() { return false; }
+};
+
+class ChunkPool {
+ TenuredChunk* head_;
+ size_t count_;
+
+ public:
+ ChunkPool() : head_(nullptr), count_(0) {}
+ ChunkPool(const ChunkPool& other) = delete;
+ ChunkPool(ChunkPool&& other) { *this = std::move(other); }
+
+ ~ChunkPool() {
+ MOZ_ASSERT(!head_);
+ MOZ_ASSERT(count_ == 0);
+ }
+
+ ChunkPool& operator=(const ChunkPool& other) = delete;
+ ChunkPool& operator=(ChunkPool&& other) {
+ head_ = other.head_;
+ other.head_ = nullptr;
+ count_ = other.count_;
+ other.count_ = 0;
+ return *this;
+ }
+
+ bool empty() const { return !head_; }
+ size_t count() const { return count_; }
+
+ TenuredChunk* head() {
+ MOZ_ASSERT(head_);
+ return head_;
+ }
+ TenuredChunk* pop();
+ void push(TenuredChunk* chunk);
+ TenuredChunk* remove(TenuredChunk* chunk);
+
+ void sort();
+
+ private:
+ TenuredChunk* mergeSort(TenuredChunk* list, size_t count);
+ bool isSorted() const;
+
+#ifdef DEBUG
+ public:
+ bool contains(TenuredChunk* chunk) const;
+ bool verify() const;
+ void verifyChunks() const;
+#endif
+
+ public:
+ // Pool mutation does not invalidate an Iter unless the mutation
+ // is of the TenuredChunk currently being visited by the Iter.
+ class Iter {
+ public:
+ explicit Iter(ChunkPool& pool) : current_(pool.head_) {}
+ bool done() const { return !current_; }
+ void next();
+ TenuredChunk* get() const { return current_; }
+ operator TenuredChunk*() const { return get(); }
+ TenuredChunk* operator->() const { return get(); }
+
+ private:
+ TenuredChunk* current_;
+ };
+};
+
+class BackgroundMarkTask : public GCParallelTask {
+ public:
+ explicit BackgroundMarkTask(GCRuntime* gc);
+ void setBudget(const SliceBudget& budget) { this->budget = budget; }
+ void run(AutoLockHelperThreadState& lock) override;
+
+ private:
+ SliceBudget budget;
+};
+
+class BackgroundUnmarkTask : public GCParallelTask {
+ public:
+ explicit BackgroundUnmarkTask(GCRuntime* gc);
+ void initZones();
+ void run(AutoLockHelperThreadState& lock) override;
+
+ ZoneVector zones;
+};
+
+class BackgroundSweepTask : public GCParallelTask {
+ public:
+ explicit BackgroundSweepTask(GCRuntime* gc);
+ void run(AutoLockHelperThreadState& lock) override;
+};
+
+class BackgroundFreeTask : public GCParallelTask {
+ public:
+ explicit BackgroundFreeTask(GCRuntime* gc);
+ void run(AutoLockHelperThreadState& lock) override;
+};
+
+// Performs extra allocation off thread so that when memory is required on the
+// main thread it will already be available and waiting.
+class BackgroundAllocTask : public GCParallelTask {
+ // Guarded by the GC lock.
+ GCLockData<ChunkPool&> chunkPool_;
+
+ const bool enabled_;
+
+ public:
+ BackgroundAllocTask(GCRuntime* gc, ChunkPool& pool);
+ bool enabled() const { return enabled_; }
+
+ void run(AutoLockHelperThreadState& lock) override;
+};
+
+// Search the provided chunks for free arenas and decommit them.
+class BackgroundDecommitTask : public GCParallelTask {
+ public:
+ explicit BackgroundDecommitTask(GCRuntime* gc);
+ void run(AutoLockHelperThreadState& lock) override;
+};
+
+template <typename F>
+struct Callback {
+ F op;
+ void* data;
+
+ Callback() : op(nullptr), data(nullptr) {}
+ Callback(F op, void* data) : op(op), data(data) {}
+};
+
+template <typename F>
+using CallbackVector = Vector<Callback<F>, 4, SystemAllocPolicy>;
+
+typedef HashMap<Value*, const char*, DefaultHasher<Value*>, SystemAllocPolicy>
+ RootedValueMap;
+
+using AllocKinds = mozilla::EnumSet<AllocKind, uint64_t>;
+
+// A singly linked list of zones.
+class ZoneList {
+ static Zone* const End;
+
+ Zone* head;
+ Zone* tail;
+
+ public:
+ ZoneList();
+ ~ZoneList();
+
+ bool isEmpty() const;
+ Zone* front() const;
+
+ void prepend(Zone* zone);
+ void append(Zone* zone);
+ void prependList(ZoneList&& other);
+ void appendList(ZoneList&& other);
+ Zone* removeFront();
+ void clear();
+
+ private:
+ explicit ZoneList(Zone* singleZone);
+ void check() const;
+
+ ZoneList(const ZoneList& other) = delete;
+ ZoneList& operator=(const ZoneList& other) = delete;
+};
+
+struct WeakCacheToSweep {
+ JS::detail::WeakCacheBase* cache;
+ JS::Zone* zone;
+};
+
+class WeakCacheSweepIterator {
+ using WeakCacheBase = JS::detail::WeakCacheBase;
+
+ JS::Zone* sweepZone;
+ WeakCacheBase* sweepCache;
+
+ public:
+ explicit WeakCacheSweepIterator(JS::Zone* sweepGroup);
+
+ bool done() const;
+ WeakCacheToSweep get() const;
+ void next();
+
+ private:
+ void settle();
+};
+
+struct SweepingTracer final : public GenericTracerImpl<SweepingTracer> {
+ explicit SweepingTracer(JSRuntime* rt);
+
+ private:
+ template <typename T>
+ void onEdge(T** thingp, const char* name);
+ friend class GenericTracerImpl<SweepingTracer>;
+};
+
+class GCRuntime {
+ public:
+ explicit GCRuntime(JSRuntime* rt);
+ [[nodiscard]] bool init(uint32_t maxbytes);
+ bool wasInitialized() const { return initialized; }
+ void finishRoots();
+ void finish();
+
+ Zone* atomsZone() {
+ Zone* zone = zones()[0];
+ MOZ_ASSERT(JS::shadow::Zone::from(zone)->isAtomsZone());
+ return zone;
+ }
+ Zone* maybeSharedAtomsZone() { return sharedAtomsZone_; }
+
+ [[nodiscard]] bool freezeSharedAtomsZone();
+ void restoreSharedAtomsZone();
+
+ JS::HeapState heapState() const { return heapState_; }
+
+ inline bool hasZealMode(ZealMode mode);
+ inline void clearZealMode(ZealMode mode);
+ inline bool needZealousGC();
+ inline bool hasIncrementalTwoSliceZealMode();
+
+ [[nodiscard]] bool addRoot(Value* vp, const char* name);
+ void removeRoot(Value* vp);
+
+ [[nodiscard]] bool setParameter(JSContext* cx, JSGCParamKey key,
+ uint32_t value);
+ void resetParameter(JSContext* cx, JSGCParamKey key);
+ uint32_t getParameter(JSGCParamKey key);
+
+ void setPerformanceHint(PerformanceHint hint);
+ bool isInPageLoad() const { return inPageLoadCount != 0; }
+
+ [[nodiscard]] bool triggerGC(JS::GCReason reason);
+ // Check whether to trigger a zone GC after allocating GC cells.
+ void maybeTriggerGCAfterAlloc(Zone* zone);
+ // Check whether to trigger a zone GC after malloc memory.
+ void maybeTriggerGCAfterMalloc(Zone* zone);
+ bool maybeTriggerGCAfterMalloc(Zone* zone, const HeapSize& heap,
+ const HeapThreshold& threshold,
+ JS::GCReason reason);
+ // The return value indicates if we were able to do the GC.
+ bool triggerZoneGC(Zone* zone, JS::GCReason reason, size_t usedBytes,
+ size_t thresholdBytes);
+
+ void maybeGC();
+
+ // Return whether we want to run a major GC. If eagerOk is true, include eager
+ // triggers (eg EAGER_ALLOC_TRIGGER) in this determination, and schedule all
+ // zones that exceed the eager thresholds.
+ JS::GCReason wantMajorGC(bool eagerOk);
+ bool checkEagerAllocTrigger(const HeapSize& size,
+ const HeapThreshold& threshold);
+
+ // Do a minor GC if requested, followed by a major GC if requested. The return
+ // value indicates whether a major GC was performed.
+ bool gcIfRequested() { return gcIfRequestedImpl(false); }
+
+ // Internal function to do a GC if previously requested. But if not and
+ // eagerOk, do an eager GC for all Zones that have exceeded the eager
+ // thresholds.
+ //
+ // Return whether a major GC was performed or started.
+ bool gcIfRequestedImpl(bool eagerOk);
+
+ void gc(JS::GCOptions options, JS::GCReason reason);
+ void startGC(JS::GCOptions options, JS::GCReason reason,
+ const SliceBudget& budget);
+ void gcSlice(JS::GCReason reason, const SliceBudget& budget);
+ void finishGC(JS::GCReason reason);
+ void abortGC();
+ void startDebugGC(JS::GCOptions options, const SliceBudget& budget);
+ void debugGCSlice(const SliceBudget& budget);
+
+ void runDebugGC();
+ void notifyRootsRemoved();
+
+ enum TraceOrMarkRuntime { TraceRuntime, MarkRuntime };
+ void traceRuntime(JSTracer* trc, AutoTraceSession& session);
+ void traceRuntimeForMinorGC(JSTracer* trc, AutoGCSession& session);
+
+ void purgeRuntimeForMinorGC();
+
+ void shrinkBuffers();
+ void onOutOfMallocMemory();
+ void onOutOfMallocMemory(const AutoLockGC& lock);
+
+ Nursery& nursery() { return nursery_.ref(); }
+ gc::StoreBuffer& storeBuffer() { return storeBuffer_.ref(); }
+
+ void minorGC(JS::GCReason reason,
+ gcstats::PhaseKind phase = gcstats::PhaseKind::MINOR_GC)
+ JS_HAZ_GC_CALL;
+ void evictNursery(JS::GCReason reason = JS::GCReason::EVICT_NURSERY) {
+ minorGC(reason, gcstats::PhaseKind::EVICT_NURSERY);
+ }
+
+ void* addressOfNurseryPosition() {
+ return nursery_.refNoCheck().addressOfPosition();
+ }
+
+ const void* addressOfLastBufferedWholeCell() {
+ return storeBuffer_.refNoCheck().addressOfLastBufferedWholeCell();
+ }
+
+#ifdef JS_GC_ZEAL
+ const uint32_t* addressOfZealModeBits() { return &zealModeBits.refNoCheck(); }
+ void getZealBits(uint32_t* zealBits, uint32_t* frequency,
+ uint32_t* nextScheduled);
+ void setZeal(uint8_t zeal, uint32_t frequency);
+ void unsetZeal(uint8_t zeal);
+ bool parseAndSetZeal(const char* str);
+ void setNextScheduled(uint32_t count);
+ void verifyPreBarriers();
+ void maybeVerifyPreBarriers(bool always);
+ bool selectForMarking(JSObject* object);
+ void clearSelectedForMarking();
+ void setDeterministic(bool enable);
+ void setMarkStackLimit(size_t limit, AutoLockGC& lock);
+#endif
+
+ uint64_t nextCellUniqueId() {
+ MOZ_ASSERT(nextCellUniqueId_ > 0);
+ uint64_t uid = ++nextCellUniqueId_;
+ return uid;
+ }
+
+ void setLowMemoryState(bool newState) { lowMemoryState = newState; }
+ bool systemHasLowMemory() const { return lowMemoryState; }
+
+ public:
+ // Internal public interface
+ ZoneVector& zones() { return zones_.ref(); }
+ gcstats::Statistics& stats() { return stats_.ref(); }
+ const gcstats::Statistics& stats() const { return stats_.ref(); }
+ State state() const { return incrementalState; }
+ bool isHeapCompacting() const { return state() == State::Compact; }
+ bool isForegroundSweeping() const { return state() == State::Sweep; }
+ bool isBackgroundSweeping() const { return sweepTask.wasStarted(); }
+ bool isBackgroundMarking() const { return markTask.wasStarted(); }
+ void waitBackgroundSweepEnd();
+ void waitBackgroundAllocEnd() { allocTask.cancelAndWait(); }
+ void waitBackgroundFreeEnd();
+ void waitForBackgroundTasks();
+ bool isWaitingOnBackgroundTask() const;
+
+ void lockGC() { lock.lock(); }
+ bool tryLockGC() { return lock.tryLock(); }
+ void unlockGC() { lock.unlock(); }
+
+#ifdef DEBUG
+ void assertCurrentThreadHasLockedGC() const {
+ lock.assertOwnedByCurrentThread();
+ }
+#endif // DEBUG
+
+ void setAlwaysPreserveCode() { alwaysPreserveCode = true; }
+
+ bool isIncrementalGCAllowed() const { return incrementalAllowed; }
+ void disallowIncrementalGC() { incrementalAllowed = false; }
+
+ void setIncrementalGCEnabled(bool enabled);
+
+ bool isIncrementalGCEnabled() const { return incrementalGCEnabled; }
+ bool isPerZoneGCEnabled() const { return perZoneGCEnabled; }
+ bool isCompactingGCEnabled() const;
+ bool isParallelMarkingEnabled() const { return parallelMarkingEnabled; }
+
+ bool isIncrementalGCInProgress() const {
+ return state() != State::NotActive && !isVerifyPreBarriersEnabled();
+ }
+
+ bool hasForegroundWork() const;
+
+ bool isShrinkingGC() const { return gcOptions() == JS::GCOptions::Shrink; }
+
+ bool isShutdownGC() const { return gcOptions() == JS::GCOptions::Shutdown; }
+
+#ifdef DEBUG
+ bool isShuttingDown() const { return hadShutdownGC; }
+#endif
+
+ bool initSweepActions();
+
+ void setGrayRootsTracer(JSGrayRootsTracer traceOp, void* data);
+ [[nodiscard]] bool addBlackRootsTracer(JSTraceDataOp traceOp, void* data);
+ void removeBlackRootsTracer(JSTraceDataOp traceOp, void* data);
+ void clearBlackAndGrayRootTracers();
+
+ void setGCCallback(JSGCCallback callback, void* data);
+ void callGCCallback(JSGCStatus status, JS::GCReason reason) const;
+ void setObjectsTenuredCallback(JSObjectsTenuredCallback callback, void* data);
+ void callObjectsTenuredCallback();
+ [[nodiscard]] bool addFinalizeCallback(JSFinalizeCallback callback,
+ void* data);
+ void removeFinalizeCallback(JSFinalizeCallback func);
+ void setHostCleanupFinalizationRegistryCallback(
+ JSHostCleanupFinalizationRegistryCallback callback, void* data);
+ void callHostCleanupFinalizationRegistryCallback(
+ JSFunction* doCleanup, GlobalObject* incumbentGlobal);
+ [[nodiscard]] bool addWeakPointerZonesCallback(
+ JSWeakPointerZonesCallback callback, void* data);
+ void removeWeakPointerZonesCallback(JSWeakPointerZonesCallback callback);
+ [[nodiscard]] bool addWeakPointerCompartmentCallback(
+ JSWeakPointerCompartmentCallback callback, void* data);
+ void removeWeakPointerCompartmentCallback(
+ JSWeakPointerCompartmentCallback callback);
+ JS::GCSliceCallback setSliceCallback(JS::GCSliceCallback callback);
+ JS::GCNurseryCollectionCallback setNurseryCollectionCallback(
+ JS::GCNurseryCollectionCallback callback);
+ JS::DoCycleCollectionCallback setDoCycleCollectionCallback(
+ JS::DoCycleCollectionCallback callback);
+
+ bool addFinalizationRegistry(JSContext* cx,
+ Handle<FinalizationRegistryObject*> registry);
+ bool registerWithFinalizationRegistry(JSContext* cx, HandleObject target,
+ HandleObject record);
+ void queueFinalizationRegistryForCleanup(FinalizationQueueObject* queue);
+
+ void nukeFinalizationRecordWrapper(JSObject* wrapper,
+ FinalizationRecordObject* record);
+ void nukeWeakRefWrapper(JSObject* wrapper, WeakRefObject* record);
+
+ void setFullCompartmentChecks(bool enable);
+
+ // Get the main marking tracer.
+ GCMarker& marker() { return *markers[0]; }
+
+ JS::Zone* getCurrentSweepGroup() { return currentSweepGroup; }
+ unsigned getCurrentSweepGroupIndex() {
+ MOZ_ASSERT_IF(unsigned(state()) < unsigned(State::Sweep),
+ sweepGroupIndex == 0);
+ return sweepGroupIndex;
+ }
+
+ uint64_t gcNumber() const { return number; }
+ void incGcNumber() { ++number; }
+
+ uint64_t minorGCCount() const { return minorGCNumber; }
+ void incMinorGcNumber() { ++minorGCNumber; }
+
+ uint64_t majorGCCount() const { return majorGCNumber; }
+ void incMajorGcNumber() { ++majorGCNumber; }
+
+ uint64_t gcSliceCount() const { return sliceNumber; }
+ void incGcSliceNumber() { ++sliceNumber; }
+
+ int64_t defaultSliceBudgetMS() const { return defaultTimeBudgetMS_; }
+
+ bool isIncrementalGc() const { return isIncremental; }
+ bool isFullGc() const { return isFull; }
+ bool isCompactingGc() const { return isCompacting; }
+ bool didCompactZones() const { return isCompacting && zonesCompacted; }
+
+ bool areGrayBitsValid() const { return grayBitsValid; }
+ void setGrayBitsInvalid() { grayBitsValid = false; }
+
+ mozilla::TimeStamp lastGCStartTime() const { return lastGCStartTime_; }
+ mozilla::TimeStamp lastGCEndTime() const { return lastGCEndTime_; }
+
+ bool majorGCRequested() const {
+ return majorGCTriggerReason != JS::GCReason::NO_REASON;
+ }
+
+ double computeHeapGrowthFactor(size_t lastBytes);
+ size_t computeTriggerBytes(double growthFactor, size_t lastBytes);
+
+ inline void updateOnFreeArenaAlloc(const TenuredChunkInfo& info);
+ void updateOnArenaFree() { ++numArenasFreeCommitted; }
+
+ ChunkPool& fullChunks(const AutoLockGC& lock) { return fullChunks_.ref(); }
+ ChunkPool& availableChunks(const AutoLockGC& lock) {
+ return availableChunks_.ref();
+ }
+ ChunkPool& emptyChunks(const AutoLockGC& lock) { return emptyChunks_.ref(); }
+ const ChunkPool& fullChunks(const AutoLockGC& lock) const {
+ return fullChunks_.ref();
+ }
+ const ChunkPool& availableChunks(const AutoLockGC& lock) const {
+ return availableChunks_.ref();
+ }
+ const ChunkPool& emptyChunks(const AutoLockGC& lock) const {
+ return emptyChunks_.ref();
+ }
+ using NonEmptyChunksIter = ChainedIterator<ChunkPool::Iter, 2>;
+ NonEmptyChunksIter allNonEmptyChunks(const AutoLockGC& lock) {
+ return NonEmptyChunksIter(availableChunks(lock), fullChunks(lock));
+ }
+ uint32_t minEmptyChunkCount(const AutoLockGC& lock) const {
+ return minEmptyChunkCount_;
+ }
+ uint32_t maxEmptyChunkCount(const AutoLockGC& lock) const {
+ return maxEmptyChunkCount_;
+ }
+#ifdef DEBUG
+ void verifyAllChunks();
+#endif
+
+ TenuredChunk* getOrAllocChunk(AutoLockGCBgAlloc& lock);
+ void recycleChunk(TenuredChunk* chunk, const AutoLockGC& lock);
+
+#ifdef JS_GC_ZEAL
+ void startVerifyPreBarriers();
+ void endVerifyPreBarriers();
+ void finishVerifier();
+ bool isVerifyPreBarriersEnabled() const { return verifyPreData.refNoCheck(); }
+ bool shouldYieldForZeal(ZealMode mode);
+#else
+ bool isVerifyPreBarriersEnabled() const { return false; }
+#endif
+
+#ifdef JSGC_HASH_TABLE_CHECKS
+ void checkHashTablesAfterMovingGC();
+#endif
+
+#ifdef DEBUG
+ // Crawl the heap to check whether an arbitary pointer is within a cell of
+ // the given kind.
+ bool isPointerWithinTenuredCell(void* ptr, JS::TraceKind traceKind);
+
+ bool hasZone(Zone* target);
+#endif
+
+ // Queue memory memory to be freed on a background thread if possible.
+ void queueUnusedLifoBlocksForFree(LifoAlloc* lifo);
+ void queueAllLifoBlocksForFreeAfterMinorGC(LifoAlloc* lifo);
+ void queueBuffersForFreeAfterMinorGC(Nursery::BufferSet& buffers);
+
+ // Public here for ReleaseArenaLists and FinalizeTypedArenas.
+ void releaseArena(Arena* arena, const AutoLockGC& lock);
+
+ // Allocator
+ template <AllowGC allowGC>
+ [[nodiscard]] bool checkAllocatorState(JSContext* cx, AllocKind kind);
+ template <JS::TraceKind kind, AllowGC allowGC>
+ void* tryNewNurseryCell(JSContext* cx, size_t thingSize, AllocSite* site);
+ template <AllowGC allowGC>
+ static void* tryNewTenuredThing(JSContext* cx, AllocKind kind,
+ size_t thingSize);
+ static void* refillFreeListInGC(Zone* zone, AllocKind thingKind);
+
+ // Delayed marking.
+ void delayMarkingChildren(gc::Cell* cell, MarkColor color);
+ bool hasDelayedMarking() const;
+ void markAllDelayedChildren(ShouldReportMarkTime reportTime);
+
+ /*
+ * Concurrent sweep infrastructure.
+ */
+ void startTask(GCParallelTask& task, AutoLockHelperThreadState& lock);
+ void joinTask(GCParallelTask& task, AutoLockHelperThreadState& lock);
+ void updateHelperThreadCount();
+ bool updateMarkersVector();
+ size_t parallelWorkerCount() const;
+ size_t markingWorkerCount() const;
+
+ // WeakRefs
+ bool registerWeakRef(HandleObject target, HandleObject weakRef);
+ void traceKeptObjects(JSTracer* trc);
+
+ JS::GCReason lastStartReason() const { return initialReason; }
+
+ void updateAllocationRates();
+
+#ifdef DEBUG
+ const GCVector<HeapPtr<JS::Value>, 0, SystemAllocPolicy>& getTestMarkQueue()
+ const;
+ [[nodiscard]] bool appendTestMarkQueue(const JS::Value& value);
+ void clearTestMarkQueue();
+ size_t testMarkQueuePos() const;
+#endif
+
+ private:
+ enum IncrementalResult { ResetIncremental = 0, Ok };
+
+ [[nodiscard]] bool setParameter(JSGCParamKey key, uint32_t value,
+ AutoLockGC& lock);
+ void resetParameter(JSGCParamKey key, AutoLockGC& lock);
+ uint32_t getParameter(JSGCParamKey key, const AutoLockGC& lock);
+ bool setThreadParameter(JSGCParamKey key, uint32_t value, AutoLockGC& lock);
+ void resetThreadParameter(JSGCParamKey key, AutoLockGC& lock);
+ void updateThreadDataStructures(AutoLockGC& lock);
+
+ JS::GCOptions gcOptions() const { return maybeGcOptions.ref().ref(); }
+
+ TriggerResult checkHeapThreshold(Zone* zone, const HeapSize& heapSize,
+ const HeapThreshold& heapThreshold);
+
+ void updateSchedulingStateOnGCStart();
+ void updateSchedulingStateAfterCollection(mozilla::TimeStamp currentTime);
+ void updateAllGCStartThresholds();
+
+ // For ArenaLists::allocateFromArena()
+ friend class ArenaLists;
+ TenuredChunk* pickChunk(AutoLockGCBgAlloc& lock);
+ Arena* allocateArena(TenuredChunk* chunk, Zone* zone, AllocKind kind,
+ ShouldCheckThresholds checkThresholds,
+ const AutoLockGC& lock);
+
+ // Allocator internals
+ void gcIfNeededAtAllocation(JSContext* cx);
+ static void* refillFreeList(JSContext* cx, AllocKind thingKind);
+ void attemptLastDitchGC(JSContext* cx);
+#ifdef DEBUG
+ static void checkIncrementalZoneState(JSContext* cx, void* ptr);
+#endif
+
+ /*
+ * Return the list of chunks that can be released outside the GC lock.
+ * Must be called either during the GC or with the GC lock taken.
+ */
+ friend class BackgroundDecommitTask;
+ bool tooManyEmptyChunks(const AutoLockGC& lock);
+ ChunkPool expireEmptyChunkPool(const AutoLockGC& lock);
+ void freeEmptyChunks(const AutoLockGC& lock);
+ void prepareToFreeChunk(TenuredChunkInfo& info);
+ void setMinEmptyChunkCount(uint32_t value, const AutoLockGC& lock);
+ void setMaxEmptyChunkCount(uint32_t value, const AutoLockGC& lock);
+
+ friend class BackgroundAllocTask;
+ bool wantBackgroundAllocation(const AutoLockGC& lock) const;
+ void startBackgroundAllocTaskIfIdle();
+
+ void requestMajorGC(JS::GCReason reason);
+ SliceBudget defaultBudget(JS::GCReason reason, int64_t millis);
+ bool maybeIncreaseSliceBudget(SliceBudget& budget);
+ bool maybeIncreaseSliceBudgetForLongCollections(SliceBudget& budget);
+ bool maybeIncreaseSliceBudgetForUrgentCollections(SliceBudget& budget);
+ IncrementalResult budgetIncrementalGC(bool nonincrementalByAPI,
+ JS::GCReason reason,
+ SliceBudget& budget);
+ void checkZoneIsScheduled(Zone* zone, JS::GCReason reason,
+ const char* trigger);
+ IncrementalResult resetIncrementalGC(GCAbortReason reason);
+
+ // Assert if the system state is such that we should never
+ // receive a request to do GC work.
+ void checkCanCallAPI();
+
+ // Check if the system state is such that GC has been supressed
+ // or otherwise delayed.
+ [[nodiscard]] bool checkIfGCAllowedInCurrentState(JS::GCReason reason);
+
+ gcstats::ZoneGCStats scanZonesBeforeGC();
+
+ void setGCOptions(JS::GCOptions options);
+
+ void collect(bool nonincrementalByAPI, const SliceBudget& budget,
+ JS::GCReason reason) JS_HAZ_GC_CALL;
+
+ /*
+ * Run one GC "cycle" (either a slice of incremental GC or an entire
+ * non-incremental GC).
+ *
+ * Returns:
+ * * ResetIncremental if we "reset" an existing incremental GC, which would
+ * force us to run another cycle or
+ * * Ok otherwise.
+ */
+ [[nodiscard]] IncrementalResult gcCycle(bool nonincrementalByAPI,
+ const SliceBudget& budgetArg,
+ JS::GCReason reason);
+ bool shouldRepeatForDeadZone(JS::GCReason reason);
+
+ void incrementalSlice(SliceBudget& budget, JS::GCReason reason,
+ bool budgetWasIncreased);
+
+ bool mightSweepInThisSlice(bool nonIncremental);
+ void collectNurseryFromMajorGC(JS::GCReason reason);
+ void collectNursery(JS::GCOptions options, JS::GCReason reason,
+ gcstats::PhaseKind phase);
+
+ friend class AutoCallGCCallbacks;
+ void maybeCallGCCallback(JSGCStatus status, JS::GCReason reason);
+
+ void startCollection(JS::GCReason reason);
+
+ void purgeRuntime();
+ [[nodiscard]] bool beginPreparePhase(JS::GCReason reason,
+ AutoGCSession& session);
+ bool prepareZonesForCollection(JS::GCReason reason, bool* isFullOut);
+ void unmarkWeakMaps();
+ void endPreparePhase(JS::GCReason reason);
+ void beginMarkPhase(AutoGCSession& session);
+ bool shouldPreserveJITCode(JS::Realm* realm,
+ const mozilla::TimeStamp& currentTime,
+ JS::GCReason reason, bool canAllocateMoreCode,
+ bool isActiveCompartment);
+ void discardJITCodeForGC();
+ void startBackgroundFreeAfterMinorGC();
+ void relazifyFunctionsForShrinkingGC();
+ void purgePropMapTablesForShrinkingGC();
+ void purgeSourceURLsForShrinkingGC();
+ void traceRuntimeForMajorGC(JSTracer* trc, AutoGCSession& session);
+ void traceRuntimeAtoms(JSTracer* trc);
+ void traceRuntimeCommon(JSTracer* trc, TraceOrMarkRuntime traceOrMark);
+ void traceEmbeddingBlackRoots(JSTracer* trc);
+ void traceEmbeddingGrayRoots(JSTracer* trc);
+ IncrementalProgress traceEmbeddingGrayRoots(JSTracer* trc,
+ SliceBudget& budget);
+ void checkNoRuntimeRoots(AutoGCSession& session);
+ void maybeDoCycleCollection();
+ void findDeadCompartments();
+
+ friend class BackgroundMarkTask;
+ enum ParallelMarking : bool {
+ SingleThreadedMarking = false,
+ AllowParallelMarking = true
+ };
+ IncrementalProgress markUntilBudgetExhausted(
+ SliceBudget& sliceBudget,
+ ParallelMarking allowParallelMarking = SingleThreadedMarking,
+ ShouldReportMarkTime reportTime = ReportMarkTime);
+ bool canMarkInParallel() const;
+
+ bool hasMarkingWork(MarkColor color) const;
+
+ void drainMarkStack();
+
+#ifdef DEBUG
+ void assertNoMarkingWork() const;
+#else
+ void assertNoMarkingWork() const {}
+#endif
+
+ void markDelayedChildren(gc::Arena* arena, MarkColor color);
+ void processDelayedMarkingList(gc::MarkColor color);
+ void rebuildDelayedMarkingList();
+ void appendToDelayedMarkingList(gc::Arena** listTail, gc::Arena* arena);
+ void resetDelayedMarking();
+ template <typename F>
+ void forEachDelayedMarkingArena(F&& f);
+
+ template <class ZoneIterT>
+ IncrementalProgress markWeakReferences(SliceBudget& budget);
+ IncrementalProgress markWeakReferencesInCurrentGroup(SliceBudget& budget);
+ template <class ZoneIterT>
+ IncrementalProgress markGrayRoots(SliceBudget& budget,
+ gcstats::PhaseKind phase);
+ void markBufferedGrayRoots(JS::Zone* zone);
+ IncrementalProgress markAllWeakReferences();
+ void markAllGrayReferences(gcstats::PhaseKind phase);
+
+ // The mark queue is a testing-only feature for controlling mark ordering and
+ // yield timing.
+ enum MarkQueueProgress {
+ QueueYielded, // End this incremental GC slice, if possible
+ QueueComplete, // Done with the queue
+ QueueSuspended // Continue the GC without ending the slice
+ };
+ MarkQueueProgress processTestMarkQueue();
+
+ // GC Sweeping. Implemented in Sweeping.cpp.
+ void beginSweepPhase(JS::GCReason reason, AutoGCSession& session);
+ void dropStringWrappers();
+ void groupZonesForSweeping(JS::GCReason reason);
+ [[nodiscard]] bool findSweepGroupEdges();
+ [[nodiscard]] bool addEdgesForMarkQueue();
+ void getNextSweepGroup();
+ void resetGrayList(Compartment* comp);
+ IncrementalProgress beginMarkingSweepGroup(JS::GCContext* gcx,
+ SliceBudget& budget);
+ IncrementalProgress markGrayRootsInCurrentGroup(JS::GCContext* gcx,
+ SliceBudget& budget);
+ IncrementalProgress markGray(JS::GCContext* gcx, SliceBudget& budget);
+ IncrementalProgress endMarkingSweepGroup(JS::GCContext* gcx,
+ SliceBudget& budget);
+ void markIncomingGrayCrossCompartmentPointers();
+ IncrementalProgress beginSweepingSweepGroup(JS::GCContext* gcx,
+ SliceBudget& budget);
+ void initBackgroundSweep(Zone* zone, JS::GCContext* gcx,
+ const FinalizePhase& phase);
+ IncrementalProgress markDuringSweeping(JS::GCContext* gcx,
+ SliceBudget& budget);
+ void updateAtomsBitmap();
+ void sweepCCWrappers();
+ void sweepRealmGlobals();
+ void sweepEmbeddingWeakPointers(JS::GCContext* gcx);
+ void sweepMisc();
+ void sweepCompressionTasks();
+ void sweepWeakMaps();
+ void sweepUniqueIds();
+ void sweepDebuggerOnMainThread(JS::GCContext* gcx);
+ void sweepJitDataOnMainThread(JS::GCContext* gcx);
+ void sweepFinalizationObserversOnMainThread();
+ void traceWeakFinalizationObserverEdges(JSTracer* trc, Zone* zone);
+ void sweepWeakRefs();
+ IncrementalProgress endSweepingSweepGroup(JS::GCContext* gcx,
+ SliceBudget& budget);
+ IncrementalProgress performSweepActions(SliceBudget& sliceBudget);
+ void startSweepingAtomsTable();
+ IncrementalProgress sweepAtomsTable(JS::GCContext* gcx, SliceBudget& budget);
+ IncrementalProgress sweepWeakCaches(JS::GCContext* gcx, SliceBudget& budget);
+ IncrementalProgress finalizeAllocKind(JS::GCContext* gcx,
+ SliceBudget& budget);
+ bool foregroundFinalize(JS::GCContext* gcx, Zone* zone, AllocKind thingKind,
+ js::SliceBudget& sliceBudget,
+ SortedArenaList& sweepList);
+ IncrementalProgress sweepPropMapTree(JS::GCContext* gcx, SliceBudget& budget);
+ void endSweepPhase(bool lastGC);
+ void queueZonesAndStartBackgroundSweep(ZoneList&& zones);
+ void sweepFromBackgroundThread(AutoLockHelperThreadState& lock);
+ void startBackgroundFree();
+ void freeFromBackgroundThread(AutoLockHelperThreadState& lock);
+ void sweepBackgroundThings(ZoneList& zones);
+ void backgroundFinalize(JS::GCContext* gcx, Zone* zone, AllocKind kind,
+ Arena** empty);
+ void assertBackgroundSweepingFinished();
+
+ bool allCCVisibleZonesWereCollected();
+ void sweepZones(JS::GCContext* gcx, bool destroyingRuntime);
+ bool shouldDecommit() const;
+ void startDecommit();
+ void decommitEmptyChunks(const bool& cancel, AutoLockGC& lock);
+ void decommitFreeArenas(const bool& cancel, AutoLockGC& lock);
+ void decommitFreeArenasWithoutUnlocking(const AutoLockGC& lock);
+
+ // Compacting GC. Implemented in Compacting.cpp.
+ bool shouldCompact();
+ void beginCompactPhase();
+ IncrementalProgress compactPhase(JS::GCReason reason,
+ SliceBudget& sliceBudget,
+ AutoGCSession& session);
+ void endCompactPhase();
+ void sweepZoneAfterCompacting(MovingTracer* trc, Zone* zone);
+ bool canRelocateZone(Zone* zone) const;
+ [[nodiscard]] bool relocateArenas(Zone* zone, JS::GCReason reason,
+ Arena*& relocatedListOut,
+ SliceBudget& sliceBudget);
+ void updateCellPointers(Zone* zone, AllocKinds kinds);
+ void updateAllCellPointers(MovingTracer* trc, Zone* zone);
+ void updateZonePointersToRelocatedCells(Zone* zone);
+ void updateRuntimePointersToRelocatedCells(AutoGCSession& session);
+ void clearRelocatedArenas(Arena* arenaList, JS::GCReason reason);
+ void clearRelocatedArenasWithoutUnlocking(Arena* arenaList,
+ JS::GCReason reason,
+ const AutoLockGC& lock);
+ void releaseRelocatedArenas(Arena* arenaList);
+ void releaseRelocatedArenasWithoutUnlocking(Arena* arenaList,
+ const AutoLockGC& lock);
+#ifdef DEBUG
+ void protectOrReleaseRelocatedArenas(Arena* arenaList, JS::GCReason reason);
+ void protectAndHoldArenas(Arena* arenaList);
+ void unprotectHeldRelocatedArenas(const AutoLockGC& lock);
+ void releaseHeldRelocatedArenas();
+ void releaseHeldRelocatedArenasWithoutUnlocking(const AutoLockGC& lock);
+#endif
+
+ /*
+ * Whether to immediately trigger a slice after a background task
+ * finishes. This may not happen at a convenient time, so the consideration is
+ * whether the slice will run quickly or may take a long time.
+ */
+ enum ShouldTriggerSliceWhenFinished : bool {
+ DontTriggerSliceWhenFinished = false,
+ TriggerSliceWhenFinished = true
+ };
+
+ IncrementalProgress waitForBackgroundTask(
+ GCParallelTask& task, const SliceBudget& budget, bool shouldPauseMutator,
+ ShouldTriggerSliceWhenFinished triggerSlice);
+
+ void maybeRequestGCAfterBackgroundTask(const AutoLockHelperThreadState& lock);
+ void cancelRequestedGCAfterBackgroundTask();
+ void finishCollection(JS::GCReason reason);
+ void maybeStopPretenuring();
+ void checkGCStateNotInUse();
+ IncrementalProgress joinBackgroundMarkTask();
+
+#ifdef JS_GC_ZEAL
+ void computeNonIncrementalMarkingForValidation(AutoGCSession& session);
+ void validateIncrementalMarking();
+ void finishMarkingValidation();
+#endif
+
+#ifdef DEBUG
+ void checkForCompartmentMismatches();
+#endif
+
+ void callFinalizeCallbacks(JS::GCContext* gcx, JSFinalizeStatus status) const;
+ void callWeakPointerZonesCallbacks(JSTracer* trc) const;
+ void callWeakPointerCompartmentCallbacks(JSTracer* trc,
+ JS::Compartment* comp) const;
+ void callDoCycleCollectionCallback(JSContext* cx);
+
+ public:
+ JSRuntime* const rt;
+
+ // Embedders can use this zone however they wish.
+ MainThreadData<JS::Zone*> systemZone;
+
+ MainThreadData<JS::GCContext> mainThreadContext;
+
+ private:
+ // For parent runtimes, a zone containing atoms that is shared by child
+ // runtimes.
+ MainThreadData<Zone*> sharedAtomsZone_;
+
+ // All zones in the runtime. The first element is always the atoms zone.
+ MainThreadOrGCTaskData<ZoneVector> zones_;
+
+ // Any activity affecting the heap.
+ MainThreadOrGCTaskData<JS::HeapState> heapState_;
+ friend class AutoHeapSession;
+ friend class JS::AutoEnterCycleCollection;
+
+ UnprotectedData<gcstats::Statistics> stats_;
+
+ public:
+ js::StringStats stringStats;
+
+ Vector<UniquePtr<GCMarker>, 1, SystemAllocPolicy> markers;
+
+ // Delayed marking support in case we OOM pushing work onto the mark stack.
+ MainThreadOrGCTaskData<js::gc::Arena*> delayedMarkingList;
+ MainThreadOrGCTaskData<bool> delayedMarkingWorkAdded;
+#ifdef DEBUG
+ /* Count of arenas that are currently in the stack. */
+ MainThreadOrGCTaskData<size_t> markLaterArenas;
+#endif
+
+ SweepingTracer sweepingTracer;
+
+ /* Track total GC heap size for this runtime. */
+ HeapSize heapSize;
+
+ /* GC scheduling state and parameters. */
+ GCSchedulingTunables tunables;
+ GCSchedulingState schedulingState;
+ MainThreadData<bool> fullGCRequested;
+
+ // Helper thread configuration.
+ MainThreadData<double> helperThreadRatio;
+ MainThreadData<size_t> maxHelperThreads;
+ MainThreadOrGCTaskData<size_t> helperThreadCount;
+ MainThreadData<size_t> markingThreadCount;
+
+ // State used for managing atom mark bitmaps in each zone.
+ AtomMarkingRuntime atomMarking;
+
+ /*
+ * Pointer to a callback that, if set, will be used to create a
+ * budget for internally-triggered GCs.
+ */
+ MainThreadData<JS::CreateSliceBudgetCallback> createBudgetCallback;
+
+ private:
+ // Arenas used for permanent things created at startup and shared by child
+ // runtimes.
+ MainThreadData<ArenaList> permanentAtoms;
+ MainThreadData<ArenaList> permanentFatInlineAtoms;
+ MainThreadData<ArenaList> permanentWellKnownSymbols;
+
+ // When chunks are empty, they reside in the emptyChunks pool and are
+ // re-used as needed or eventually expired if not re-used. The emptyChunks
+ // pool gets refilled from the background allocation task heuristically so
+ // that empty chunks should always be available for immediate allocation
+ // without syscalls.
+ GCLockData<ChunkPool> emptyChunks_;
+
+ // Chunks which have had some, but not all, of their arenas allocated live
+ // in the available chunk lists. When all available arenas in a chunk have
+ // been allocated, the chunk is removed from the available list and moved
+ // to the fullChunks pool. During a GC, if all arenas are free, the chunk
+ // is moved back to the emptyChunks pool and scheduled for eventual
+ // release.
+ GCLockData<ChunkPool> availableChunks_;
+
+ // When all arenas in a chunk are used, it is moved to the fullChunks pool
+ // so as to reduce the cost of operations on the available lists.
+ GCLockData<ChunkPool> fullChunks_;
+
+ /*
+ * JSGC_MIN_EMPTY_CHUNK_COUNT
+ * JSGC_MAX_EMPTY_CHUNK_COUNT
+ *
+ * Controls the number of empty chunks reserved for future allocation.
+ *
+ * They can be read off main thread by the background allocation task and the
+ * background decommit task.
+ */
+ GCLockData<uint32_t> minEmptyChunkCount_;
+ GCLockData<uint32_t> maxEmptyChunkCount_;
+
+ MainThreadData<RootedValueMap> rootsHash;
+
+ // An incrementing id used to assign unique ids to cells that require one.
+ MainThreadData<uint64_t> nextCellUniqueId_;
+
+ /*
+ * Number of the committed arenas in all GC chunks including empty chunks.
+ */
+ mozilla::Atomic<uint32_t, mozilla::ReleaseAcquire> numArenasFreeCommitted;
+ MainThreadData<VerifyPreTracer*> verifyPreData;
+
+ MainThreadData<mozilla::TimeStamp> lastGCStartTime_;
+ MainThreadData<mozilla::TimeStamp> lastGCEndTime_;
+
+ WriteOnceData<bool> initialized;
+ MainThreadData<bool> incrementalGCEnabled;
+ MainThreadData<bool> perZoneGCEnabled;
+
+ mozilla::Atomic<size_t, mozilla::ReleaseAcquire> numActiveZoneIters;
+
+ /* During shutdown, the GC needs to clean up every possible object. */
+ MainThreadData<bool> cleanUpEverything;
+
+ /*
+ * The gray bits can become invalid if UnmarkGray overflows the stack. A
+ * full GC will reset this bit, since it fills in all the gray bits.
+ */
+ UnprotectedData<bool> grayBitsValid;
+
+ mozilla::Atomic<JS::GCReason, mozilla::ReleaseAcquire> majorGCTriggerReason;
+
+ /* Incremented at the start of every minor GC. */
+ MainThreadData<uint64_t> minorGCNumber;
+
+ /* Incremented at the start of every major GC. */
+ MainThreadData<uint64_t> majorGCNumber;
+
+ /* Incremented on every GC slice or minor collection. */
+ MainThreadData<uint64_t> number;
+
+ /* Incremented on every GC slice. */
+ MainThreadData<uint64_t> sliceNumber;
+
+ /* Whether the currently running GC can finish in multiple slices. */
+ MainThreadOrGCTaskData<bool> isIncremental;
+
+ /* Whether all zones are being collected in first GC slice. */
+ MainThreadData<bool> isFull;
+
+ /* Whether the heap will be compacted at the end of GC. */
+ MainThreadData<bool> isCompacting;
+
+ /* The invocation kind of the current GC, set at the start of collection. */
+ MainThreadOrGCTaskData<mozilla::Maybe<JS::GCOptions>> maybeGcOptions;
+
+ /* The initial GC reason, taken from the first slice. */
+ MainThreadData<JS::GCReason> initialReason;
+
+ /*
+ * The current incremental GC phase. This is also used internally in
+ * non-incremental GC.
+ */
+ MainThreadOrGCTaskData<State> incrementalState;
+
+ /* The incremental state at the start of this slice. */
+ MainThreadOrGCTaskData<State> initialState;
+
+ /* Whether to pay attention the zeal settings in this incremental slice. */
+#ifdef JS_GC_ZEAL
+ MainThreadData<bool> useZeal;
+#else
+ const bool useZeal;
+#endif
+
+ /* Indicates that the last incremental slice exhausted the mark stack. */
+ MainThreadData<bool> lastMarkSlice;
+
+ // Whether it's currently safe to yield to the mutator in an incremental GC.
+ MainThreadData<bool> safeToYield;
+
+ // Whether to do any marking caused by barriers on a background thread during
+ // incremental sweeping, while also sweeping zones which have finished
+ // marking.
+ MainThreadData<bool> markOnBackgroundThreadDuringSweeping;
+
+ // Whether any sweeping and decommitting will run on a separate GC helper
+ // thread.
+ MainThreadData<bool> useBackgroundThreads;
+
+#ifdef DEBUG
+ /* Shutdown has started. Further collections must be shutdown collections. */
+ MainThreadData<bool> hadShutdownGC;
+#endif
+
+ /* Singly linked list of zones to be swept in the background. */
+ HelperThreadLockData<ZoneList> backgroundSweepZones;
+
+ /*
+ * Whether to trigger a GC slice after a background task is complete, so that
+ * the collector can continue or finsish collecting. This is only used for the
+ * tasks that run concurrently with the mutator, which are background
+ * finalization and background decommit.
+ */
+ HelperThreadLockData<bool> requestSliceAfterBackgroundTask;
+
+ /*
+ * Free LIFO blocks are transferred to these allocators before being freed on
+ * a background thread.
+ */
+ HelperThreadLockData<LifoAlloc> lifoBlocksToFree;
+ MainThreadData<LifoAlloc> lifoBlocksToFreeAfterMinorGC;
+ HelperThreadLockData<Nursery::BufferSet> buffersToFreeAfterMinorGC;
+
+ /* Index of current sweep group (for stats). */
+ MainThreadData<unsigned> sweepGroupIndex;
+
+ /*
+ * Incremental sweep state.
+ */
+ MainThreadData<JS::Zone*> sweepGroups;
+ MainThreadOrGCTaskData<JS::Zone*> currentSweepGroup;
+ MainThreadData<UniquePtr<SweepAction>> sweepActions;
+ MainThreadOrGCTaskData<JS::Zone*> sweepZone;
+ MainThreadOrGCTaskData<AllocKind> sweepAllocKind;
+ MainThreadData<mozilla::Maybe<AtomsTable::SweepIterator>> maybeAtomsToSweep;
+ MainThreadOrGCTaskData<mozilla::Maybe<WeakCacheSweepIterator>>
+ weakCachesToSweep;
+ MainThreadData<bool> abortSweepAfterCurrentGroup;
+ MainThreadOrGCTaskData<IncrementalProgress> sweepMarkResult;
+
+#ifdef DEBUG
+ /*
+ * List of objects to mark at the beginning of a GC for testing purposes. May
+ * also contain string directives to change mark color or wait until different
+ * phases of the GC.
+ *
+ * This is a WeakCache because not everything in this list is guaranteed to
+ * end up marked (eg if you insert an object from an already-processed sweep
+ * group in the middle of an incremental GC). Also, the mark queue is not
+ * used during shutdown GCs. In either case, unmarked objects may need to be
+ * discarded.
+ */
+ JS::WeakCache<GCVector<HeapPtr<JS::Value>, 0, SystemAllocPolicy>>
+ testMarkQueue;
+
+ /* Position within the test mark queue. */
+ size_t queuePos;
+
+ /* The test marking queue might want to be marking a particular color. */
+ mozilla::Maybe<js::gc::MarkColor> queueMarkColor;
+
+ // During gray marking, delay AssertCellIsNotGray checks by
+ // recording the cell pointers here and checking after marking has
+ // finished.
+ MainThreadData<Vector<const Cell*, 0, SystemAllocPolicy>>
+ cellsToAssertNotGray;
+ friend void js::gc::detail::AssertCellIsNotGray(const Cell*);
+#endif
+
+ friend class SweepGroupsIter;
+
+ /*
+ * Incremental compacting state.
+ */
+ MainThreadData<bool> startedCompacting;
+ MainThreadData<ZoneList> zonesToMaybeCompact;
+ MainThreadData<size_t> zonesCompacted;
+#ifdef DEBUG
+ GCLockData<Arena*> relocatedArenasToRelease;
+#endif
+
+#ifdef JS_GC_ZEAL
+ MainThreadData<MarkingValidator*> markingValidator;
+#endif
+
+ /*
+ * Default budget for incremental GC slice. See js/SliceBudget.h.
+ *
+ * JSGC_SLICE_TIME_BUDGET_MS
+ * pref: javascript.options.mem.gc_incremental_slice_ms,
+ */
+ MainThreadData<int64_t> defaultTimeBudgetMS_;
+
+ /*
+ * We disable incremental GC if we encounter a Class with a trace hook
+ * that does not implement write barriers.
+ */
+ MainThreadData<bool> incrementalAllowed;
+
+ /*
+ * Whether compacting GC can is enabled globally.
+ *
+ * JSGC_COMPACTING_ENABLED
+ * pref: javascript.options.mem.gc_compacting
+ */
+ MainThreadData<bool> compactingEnabled;
+
+ /*
+ * Whether parallel marking is enabled globally.
+ *
+ * JSGC_PARALLEL_MARKING_ENABLED
+ * pref: javascript.options.mem.gc_parallel_marking
+ */
+ MainThreadData<bool> parallelMarkingEnabled;
+
+ MainThreadData<bool> rootsRemoved;
+
+ /*
+ * These options control the zealousness of the GC. At every allocation,
+ * nextScheduled is decremented. When it reaches zero we do a full GC.
+ *
+ * At this point, if zeal_ is one of the types that trigger periodic
+ * collection, then nextScheduled is reset to the value of zealFrequency.
+ * Otherwise, no additional GCs take place.
+ *
+ * You can control these values in several ways:
+ * - Set the JS_GC_ZEAL environment variable
+ * - Call gczeal() or schedulegc() from inside shell-executed JS code
+ * (see the help for details)
+ *
+ * If gcZeal_ == 1 then we perform GCs in select places (during MaybeGC and
+ * whenever we are notified that GC roots have been removed). This option is
+ * mainly useful to embedders.
+ *
+ * We use zeal_ == 4 to enable write barrier verification. See the comment
+ * in gc/Verifier.cpp for more information about this.
+ *
+ * zeal_ values from 8 to 10 periodically run different types of
+ * incremental GC.
+ *
+ * zeal_ value 14 performs periodic shrinking collections.
+ */
+#ifdef JS_GC_ZEAL
+ static_assert(size_t(ZealMode::Count) <= 32,
+ "Too many zeal modes to store in a uint32_t");
+ MainThreadData<uint32_t> zealModeBits;
+ MainThreadData<int> zealFrequency;
+ MainThreadData<int> nextScheduled;
+ MainThreadData<bool> deterministicOnly;
+ MainThreadData<int> zealSliceBudget;
+ MainThreadData<size_t> maybeMarkStackLimit;
+
+ MainThreadData<PersistentRooted<GCVector<JSObject*, 0, SystemAllocPolicy>>>
+ selectedForMarking;
+#endif
+
+ MainThreadData<bool> fullCompartmentChecks;
+
+ MainThreadData<uint32_t> gcCallbackDepth;
+
+ MainThreadData<Callback<JSGCCallback>> gcCallback;
+ MainThreadData<Callback<JS::DoCycleCollectionCallback>>
+ gcDoCycleCollectionCallback;
+ MainThreadData<Callback<JSObjectsTenuredCallback>> tenuredCallback;
+ MainThreadData<CallbackVector<JSFinalizeCallback>> finalizeCallbacks;
+ MainThreadOrGCTaskData<Callback<JSHostCleanupFinalizationRegistryCallback>>
+ hostCleanupFinalizationRegistryCallback;
+ MainThreadData<CallbackVector<JSWeakPointerZonesCallback>>
+ updateWeakPointerZonesCallbacks;
+ MainThreadData<CallbackVector<JSWeakPointerCompartmentCallback>>
+ updateWeakPointerCompartmentCallbacks;
+
+ /*
+ * The trace operations to trace embedding-specific GC roots. One is for
+ * tracing through black roots and the other is for tracing through gray
+ * roots. The black/gray distinction is only relevant to the cycle
+ * collector.
+ */
+ MainThreadData<CallbackVector<JSTraceDataOp>> blackRootTracers;
+ MainThreadOrGCTaskData<Callback<JSGrayRootsTracer>> grayRootTracer;
+
+ /* Always preserve JIT code during GCs, for testing. */
+ MainThreadData<bool> alwaysPreserveCode;
+
+ /* Count of the number of zones that are currently in page load. */
+ MainThreadData<size_t> inPageLoadCount;
+
+ MainThreadData<bool> lowMemoryState;
+
+ /*
+ * General purpose GC lock, used for synchronising operations on
+ * arenas and during parallel marking.
+ */
+ friend class js::AutoLockGC;
+ friend class js::AutoLockGCBgAlloc;
+ js::Mutex lock MOZ_UNANNOTATED;
+
+ /* Lock used to synchronise access to delayed marking state. */
+ js::Mutex delayedMarkingLock MOZ_UNANNOTATED;
+
+ friend class BackgroundSweepTask;
+ friend class BackgroundFreeTask;
+
+ BackgroundAllocTask allocTask;
+ BackgroundUnmarkTask unmarkTask;
+ BackgroundMarkTask markTask;
+ BackgroundSweepTask sweepTask;
+ BackgroundFreeTask freeTask;
+ BackgroundDecommitTask decommitTask;
+
+ /*
+ * During incremental sweeping, this field temporarily holds the arenas of
+ * the current AllocKind being swept in order of increasing free space.
+ */
+ MainThreadData<SortedArenaList> incrementalSweepList;
+
+ MainThreadData<Nursery> nursery_;
+
+ // The store buffer used to track tenured to nursery edges for generational
+ // GC. This is accessed off main thread when sweeping WeakCaches.
+ MainThreadOrGCTaskData<gc::StoreBuffer> storeBuffer_;
+
+ mozilla::TimeStamp lastLastDitchTime;
+
+ // The last time per-zone allocation rates were updated.
+ MainThreadData<mozilla::TimeStamp> lastAllocRateUpdateTime;
+
+ // Total collector time since per-zone allocation rates were last updated.
+ MainThreadData<mozilla::TimeDuration> collectorTimeSinceAllocRateUpdate;
+
+ friend class MarkingValidator;
+ friend class AutoEnterIteration;
+};
+
+/* Prevent compartments and zones from being collected during iteration. */
+class MOZ_RAII AutoEnterIteration {
+ GCRuntime* gc;
+
+ public:
+ explicit AutoEnterIteration(GCRuntime* gc_) : gc(gc_) {
+ ++gc->numActiveZoneIters;
+ }
+
+ ~AutoEnterIteration() {
+ MOZ_ASSERT(gc->numActiveZoneIters);
+ --gc->numActiveZoneIters;
+ }
+};
+
+#ifdef JS_GC_ZEAL
+
+inline bool GCRuntime::hasZealMode(ZealMode mode) {
+ static_assert(size_t(ZealMode::Limit) < sizeof(zealModeBits) * 8,
+ "Zeal modes must fit in zealModeBits");
+ return zealModeBits & (1 << uint32_t(mode));
+}
+
+inline void GCRuntime::clearZealMode(ZealMode mode) {
+ zealModeBits &= ~(1 << uint32_t(mode));
+ MOZ_ASSERT(!hasZealMode(mode));
+}
+
+inline bool GCRuntime::needZealousGC() {
+ if (nextScheduled > 0 && --nextScheduled == 0) {
+ if (hasZealMode(ZealMode::Alloc) || hasZealMode(ZealMode::GenerationalGC) ||
+ hasZealMode(ZealMode::IncrementalMultipleSlices) ||
+ hasZealMode(ZealMode::Compact) || hasIncrementalTwoSliceZealMode()) {
+ nextScheduled = zealFrequency;
+ }
+ return true;
+ }
+ return false;
+}
+
+inline bool GCRuntime::hasIncrementalTwoSliceZealMode() {
+ return hasZealMode(ZealMode::YieldBeforeRootMarking) ||
+ hasZealMode(ZealMode::YieldBeforeMarking) ||
+ hasZealMode(ZealMode::YieldBeforeSweeping) ||
+ hasZealMode(ZealMode::YieldBeforeSweepingAtoms) ||
+ hasZealMode(ZealMode::YieldBeforeSweepingCaches) ||
+ hasZealMode(ZealMode::YieldBeforeSweepingObjects) ||
+ hasZealMode(ZealMode::YieldBeforeSweepingNonObjects) ||
+ hasZealMode(ZealMode::YieldBeforeSweepingPropMapTrees) ||
+ hasZealMode(ZealMode::YieldWhileGrayMarking);
+}
+
+#else
+inline bool GCRuntime::hasZealMode(ZealMode mode) { return false; }
+inline void GCRuntime::clearZealMode(ZealMode mode) {}
+inline bool GCRuntime::needZealousGC() { return false; }
+inline bool GCRuntime::hasIncrementalTwoSliceZealMode() { return false; }
+#endif
+
+bool IsCurrentlyAnimating(const mozilla::TimeStamp& lastAnimationTime,
+ const mozilla::TimeStamp& currentTime);
+
+} /* namespace gc */
+} /* namespace js */
+
+#endif
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 14:40:24 +0000