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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 mozilla_CycleCollectedJSContext_h
+#define mozilla_CycleCollectedJSContext_h
+
+#include <deque>
+
+#include "mozilla/Attributes.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/dom/AtomList.h"
+#include "mozilla/dom/Promise.h"
+#include "js/GCVector.h"
+#include "js/Promise.h"
+
+#include "nsCOMPtr.h"
+#include "nsRefPtrHashtable.h"
+#include "nsTArray.h"
+
+class nsCycleCollectionNoteRootCallback;
+class nsIRunnable;
+class nsThread;
+
+namespace mozilla {
+class AutoSlowOperation;
+
+class CycleCollectedJSContext;
+class CycleCollectedJSRuntime;
+
+namespace dom {
+class Exception;
+class WorkerJSContext;
+class WorkletJSContext;
+} // namespace dom
+
+// Contains various stats about the cycle collection.
+struct CycleCollectorResults {
+ CycleCollectorResults() {
+ // Initialize here so when we increment mNumSlices the first time we're
+ // not using uninitialized memory.
+ Init();
+ }
+
+ void Init() {
+ mForcedGC = false;
+ mSuspectedAtCCStart = 0;
+ mMergedZones = false;
+ mAnyManual = false;
+ mVisitedRefCounted = 0;
+ mVisitedGCed = 0;
+ mFreedRefCounted = 0;
+ mFreedGCed = 0;
+ mFreedJSZones = 0;
+ mNumSlices = 1;
+ // mNumSlices is initialized to one, because we call Init() after the
+ // per-slice increment of mNumSlices has already occurred.
+ }
+
+ bool mForcedGC;
+ bool mMergedZones;
+ // mAnyManual is true if any slice was manually triggered, and at shutdown.
+ bool mAnyManual;
+ uint32_t mSuspectedAtCCStart;
+ uint32_t mVisitedRefCounted;
+ uint32_t mVisitedGCed;
+ uint32_t mFreedRefCounted;
+ uint32_t mFreedGCed;
+ uint32_t mFreedJSZones;
+ uint32_t mNumSlices;
+};
+
+class MicroTaskRunnable {
+ public:
+ MicroTaskRunnable() = default;
+ NS_INLINE_DECL_REFCOUNTING(MicroTaskRunnable)
+ MOZ_CAN_RUN_SCRIPT virtual void Run(AutoSlowOperation& aAso) = 0;
+ virtual bool Suppressed() { return false; }
+
+ protected:
+ virtual ~MicroTaskRunnable() = default;
+};
+
+// Store the suppressed mictotasks in another microtask so that operations
+// for the microtask queue as a whole keep working.
+class SuppressedMicroTasks : public MicroTaskRunnable {
+ public:
+ explicit SuppressedMicroTasks(CycleCollectedJSContext* aContext);
+
+ MOZ_CAN_RUN_SCRIPT_BOUNDARY void Run(AutoSlowOperation& aAso) final {}
+ virtual bool Suppressed();
+
+ CycleCollectedJSContext* mContext;
+ uint64_t mSuppressionGeneration;
+ std::deque<RefPtr<MicroTaskRunnable>> mSuppressedMicroTaskRunnables;
+};
+
+// Support for JS FinalizationRegistry objects, which allow a JS callback to be
+// registered that is called when objects die.
+//
+// We keep a vector of functions that call back into the JS engine along
+// with their associated incumbent globals, one per FinalizationRegistry object
+// that has pending cleanup work. These are run in their own task.
+class FinalizationRegistryCleanup {
+ public:
+ explicit FinalizationRegistryCleanup(CycleCollectedJSContext* aContext);
+ void Init();
+ void Destroy();
+ void QueueCallback(JSFunction* aDoCleanup, JSObject* aIncumbentGlobal);
+ MOZ_CAN_RUN_SCRIPT void DoCleanup();
+
+ private:
+ static void QueueCallback(JSFunction* aDoCleanup, JSObject* aIncumbentGlobal,
+ void* aData);
+
+ class CleanupRunnable;
+
+ struct Callback {
+ JSFunction* mCallbackFunction;
+ JSObject* mIncumbentGlobal;
+ void trace(JSTracer* trc);
+ };
+
+ // This object is part of CycleCollectedJSContext, so it's safe to have a raw
+ // pointer to its containing context here.
+ CycleCollectedJSContext* mContext;
+
+ using CallbackVector = JS::GCVector<Callback, 0, InfallibleAllocPolicy>;
+ JS::PersistentRooted<CallbackVector> mCallbacks;
+};
+
+class CycleCollectedJSContext : dom::PerThreadAtomCache, private JS::JobQueue {
+ friend class CycleCollectedJSRuntime;
+ friend class SuppressedMicroTasks;
+
+ protected:
+ CycleCollectedJSContext();
+ virtual ~CycleCollectedJSContext();
+
+ MOZ_IS_CLASS_INIT
+ nsresult Initialize(JSRuntime* aParentRuntime, uint32_t aMaxBytes);
+
+ virtual CycleCollectedJSRuntime* CreateRuntime(JSContext* aCx) = 0;
+
+ size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+ private:
+ static void PromiseRejectionTrackerCallback(
+ JSContext* aCx, bool aMutedErrors, JS::Handle<JSObject*> aPromise,
+ JS::PromiseRejectionHandlingState state, void* aData);
+
+ void AfterProcessMicrotasks();
+
+ public:
+ void ProcessStableStateQueue();
+
+ private:
+ void CleanupIDBTransactions(uint32_t aRecursionDepth);
+
+ public:
+ virtual dom::WorkerJSContext* GetAsWorkerJSContext() { return nullptr; }
+ virtual dom::WorkletJSContext* GetAsWorkletJSContext() { return nullptr; }
+
+ CycleCollectedJSRuntime* Runtime() const {
+ MOZ_ASSERT(mRuntime);
+ return mRuntime;
+ }
+
+ already_AddRefed<dom::Exception> GetPendingException() const;
+ void SetPendingException(dom::Exception* aException);
+
+ std::deque<RefPtr<MicroTaskRunnable>>& GetMicroTaskQueue();
+ std::deque<RefPtr<MicroTaskRunnable>>& GetDebuggerMicroTaskQueue();
+
+ JSContext* Context() const {
+ MOZ_ASSERT(mJSContext);
+ return mJSContext;
+ }
+
+ JS::RootingContext* RootingCx() const {
+ MOZ_ASSERT(mJSContext);
+ return JS::RootingContext::get(mJSContext);
+ }
+
+ void SetTargetedMicroTaskRecursionDepth(uint32_t aDepth) {
+ mTargetedMicroTaskRecursionDepth = aDepth;
+ }
+
+ void UpdateMicroTaskSuppressionGeneration() { ++mSuppressionGeneration; }
+
+ protected:
+ JSContext* MaybeContext() const { return mJSContext; }
+
+ public:
+ // nsThread entrypoints
+ //
+ // MOZ_CAN_RUN_SCRIPT_BOUNDARY so we don't need to annotate
+ // nsThread::ProcessNextEvent and all its callers MOZ_CAN_RUN_SCRIPT for now.
+ // But we really should!
+ MOZ_CAN_RUN_SCRIPT_BOUNDARY
+ virtual void BeforeProcessTask(bool aMightBlock);
+ // MOZ_CAN_RUN_SCRIPT_BOUNDARY so we don't need to annotate
+ // nsThread::ProcessNextEvent and all its callers MOZ_CAN_RUN_SCRIPT for now.
+ // But we really should!
+ MOZ_CAN_RUN_SCRIPT_BOUNDARY
+ virtual void AfterProcessTask(uint32_t aRecursionDepth);
+
+ // Check whether any eager thresholds have been reached, which would mean
+ // an idle GC task (minor or major) would be useful.
+ virtual void MaybePokeGC();
+
+ uint32_t RecursionDepth() const;
+
+ // Run in stable state (call through nsContentUtils)
+ void RunInStableState(already_AddRefed<nsIRunnable>&& aRunnable);
+
+ void AddPendingIDBTransaction(already_AddRefed<nsIRunnable>&& aTransaction);
+
+ // Get the CycleCollectedJSContext for a JSContext.
+ // Returns null only if Initialize() has not completed on or during
+ // destruction of the CycleCollectedJSContext.
+ static CycleCollectedJSContext* GetFor(JSContext* aCx);
+
+ // Get the current thread's CycleCollectedJSContext. Returns null if there
+ // isn't one.
+ static CycleCollectedJSContext* Get();
+
+ // Queue an async microtask to the current main or worker thread.
+ virtual void DispatchToMicroTask(
+ already_AddRefed<MicroTaskRunnable> aRunnable);
+
+ // Call EnterMicroTask when you're entering JS execution.
+ // Usually the best way to do this is to use nsAutoMicroTask.
+ void EnterMicroTask() { ++mMicroTaskLevel; }
+
+ MOZ_CAN_RUN_SCRIPT
+ void LeaveMicroTask() {
+ if (--mMicroTaskLevel == 0) {
+ PerformMicroTaskCheckPoint();
+ }
+ }
+
+ uint32_t MicroTaskLevel() const { return mMicroTaskLevel; }
+
+ void SetMicroTaskLevel(uint32_t aLevel) { mMicroTaskLevel = aLevel; }
+
+ MOZ_CAN_RUN_SCRIPT
+ bool PerformMicroTaskCheckPoint(bool aForce = false);
+
+ MOZ_CAN_RUN_SCRIPT
+ void PerformDebuggerMicroTaskCheckpoint();
+
+ bool IsInStableOrMetaStableState() const { return mDoingStableStates; }
+
+ // Storage for watching rejected promises waiting for some client to
+ // consume their rejection.
+ // Promises in this list have been rejected in the last turn of the
+ // event loop without the rejection being handled.
+ // Note that this can contain nullptrs in place of promises removed because
+ // they're consumed before it'd be reported.
+ JS::PersistentRooted<JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>>
+ mUncaughtRejections;
+
+ // Promises in this list have previously been reported as rejected
+ // (because they were in the above list), but the rejection was handled
+ // in the last turn of the event loop.
+ JS::PersistentRooted<JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>>
+ mConsumedRejections;
+ nsTArray<nsCOMPtr<nsISupports /* UncaughtRejectionObserver */>>
+ mUncaughtRejectionObservers;
+
+ virtual bool IsSystemCaller() const = 0;
+
+ // Unused on main thread. Used by AutoJSAPI on Worker and Worklet threads.
+ virtual void ReportError(JSErrorReport* aReport,
+ JS::ConstUTF8CharsZ aToStringResult) {
+ MOZ_ASSERT_UNREACHABLE("Not supported");
+ }
+
+ private:
+ // JS::JobQueue implementation: see js/public/Promise.h.
+ // SpiderMonkey uses some of these methods to enqueue promise resolution jobs.
+ // Others protect the debuggee microtask queue from the debugger's
+ // interruptions; see the comments on JS::AutoDebuggerJobQueueInterruption for
+ // details.
+ JSObject* getIncumbentGlobal(JSContext* cx) override;
+ bool enqueuePromiseJob(JSContext* cx, JS::Handle<JSObject*> promise,
+ JS::Handle<JSObject*> job,
+ JS::Handle<JSObject*> allocationSite,
+ JS::Handle<JSObject*> incumbentGlobal) override;
+ // MOZ_CAN_RUN_SCRIPT_BOUNDARY for now so we don't have to change SpiderMonkey
+ // headers. The caller presumably knows this can run script (like everything
+ // in SpiderMonkey!) and will deal.
+ MOZ_CAN_RUN_SCRIPT_BOUNDARY
+ void runJobs(JSContext* cx) override;
+ bool empty() const override;
+ class SavedMicroTaskQueue;
+ js::UniquePtr<SavedJobQueue> saveJobQueue(JSContext*) override;
+
+ private:
+ CycleCollectedJSRuntime* mRuntime;
+
+ JSContext* mJSContext;
+
+ nsCOMPtr<dom::Exception> mPendingException;
+ nsThread* mOwningThread; // Manual refcounting to avoid include hell.
+
+ struct PendingIDBTransactionData {
+ nsCOMPtr<nsIRunnable> mTransaction;
+ uint32_t mRecursionDepth;
+ };
+
+ nsTArray<nsCOMPtr<nsIRunnable>> mStableStateEvents;
+ nsTArray<PendingIDBTransactionData> mPendingIDBTransactions;
+ uint32_t mBaseRecursionDepth;
+ bool mDoingStableStates;
+
+ // If set to none 0, microtasks will be processed only when recursion depth
+ // is the set value.
+ uint32_t mTargetedMicroTaskRecursionDepth;
+
+ uint32_t mMicroTaskLevel;
+
+ std::deque<RefPtr<MicroTaskRunnable>> mPendingMicroTaskRunnables;
+ std::deque<RefPtr<MicroTaskRunnable>> mDebuggerMicroTaskQueue;
+ RefPtr<SuppressedMicroTasks> mSuppressedMicroTasks;
+ uint64_t mSuppressionGeneration;
+
+ // How many times the debugger has interrupted execution, possibly creating
+ // microtask checkpoints in places that they would not normally occur.
+ uint32_t mDebuggerRecursionDepth;
+
+ uint32_t mMicroTaskRecursionDepth;
+
+ // This implements about-to-be-notified rejected promises list in the spec.
+ // https://html.spec.whatwg.org/multipage/webappapis.html#about-to-be-notified-rejected-promises-list
+ typedef nsTArray<RefPtr<dom::Promise>> PromiseArray;
+ PromiseArray mAboutToBeNotifiedRejectedPromises;
+
+ // This is for the "outstanding rejected promises weak set" in the spec,
+ // https://html.spec.whatwg.org/multipage/webappapis.html#outstanding-rejected-promises-weak-set
+ // We use different data structure and opposite logic here to achieve the same
+ // effect. Basically this is used for tracking the rejected promise that does
+ // NOT need firing a rejectionhandled event. We will check the table to see if
+ // firing rejectionhandled event is required when a rejected promise is being
+ // handled.
+ //
+ // The rejected promise will be stored in the table if
+ // - it is unhandled, and
+ // - The unhandledrejection is not yet fired.
+ //
+ // And be removed when
+ // - it is handled, or
+ // - A unhandledrejection is fired and it isn't being handled in event
+ // handler.
+ typedef nsRefPtrHashtable<nsUint64HashKey, dom::Promise> PromiseHashtable;
+ PromiseHashtable mPendingUnhandledRejections;
+
+ class NotifyUnhandledRejections final : public CancelableRunnable {
+ public:
+ explicit NotifyUnhandledRejections(PromiseArray&& aPromises)
+ : CancelableRunnable("NotifyUnhandledRejections"),
+ mUnhandledRejections(std::move(aPromises)) {}
+
+ NS_IMETHOD Run() final;
+
+ nsresult Cancel() final;
+
+ private:
+ PromiseArray mUnhandledRejections;
+ };
+
+ FinalizationRegistryCleanup mFinalizationRegistryCleanup;
+};
+
+class MOZ_STACK_CLASS nsAutoMicroTask {
+ public:
+ nsAutoMicroTask() {
+ CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
+ if (ccjs) {
+ ccjs->EnterMicroTask();
+ }
+ }
+ MOZ_CAN_RUN_SCRIPT ~nsAutoMicroTask() {
+ CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
+ if (ccjs) {
+ ccjs->LeaveMicroTask();
+ }
+ }
+};
+
+} // namespace mozilla
+
+#endif // mozilla_CycleCollectedJSContext_h