gecko-dev/xpcom/base/CycleCollectedJSContext.h

494 строки
15 KiB
C++

/* -*- 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 <queue>
#include "mozilla/DeferredFinalize.h"
#include "mozilla/mozalloc.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/SegmentedVector.h"
#include "jsapi.h"
#include "jsfriendapi.h"
#include "nsCycleCollectionParticipant.h"
#include "nsDataHashtable.h"
#include "nsHashKeys.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
class nsCycleCollectionNoteRootCallback;
class nsIException;
class nsIRunnable;
class nsThread;
class nsWrapperCache;
namespace js {
struct Class;
} // namespace js
namespace mozilla {
class JSGCThingParticipant: public nsCycleCollectionParticipant
{
public:
constexpr JSGCThingParticipant()
: nsCycleCollectionParticipant(false) {}
NS_IMETHOD_(void) Root(void*) override
{
MOZ_ASSERT(false, "Don't call Root on GC things");
}
NS_IMETHOD_(void) Unlink(void*) override
{
MOZ_ASSERT(false, "Don't call Unlink on GC things, as they may be dead");
}
NS_IMETHOD_(void) Unroot(void*) override
{
MOZ_ASSERT(false, "Don't call Unroot on GC things, as they may be dead");
}
NS_IMETHOD_(void) DeleteCycleCollectable(void* aPtr) override
{
MOZ_ASSERT(false, "Can't directly delete a cycle collectable GC thing");
}
NS_IMETHOD TraverseNative(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
override;
NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(JSGCThingParticipant)
};
class JSZoneParticipant : public nsCycleCollectionParticipant
{
public:
constexpr JSZoneParticipant(): nsCycleCollectionParticipant(false)
{
}
NS_IMETHOD_(void) Root(void*) override
{
MOZ_ASSERT(false, "Don't call Root on GC things");
}
NS_IMETHOD_(void) Unlink(void*) override
{
MOZ_ASSERT(false, "Don't call Unlink on GC things, as they may be dead");
}
NS_IMETHOD_(void) Unroot(void*) override
{
MOZ_ASSERT(false, "Don't call Unroot on GC things, as they may be dead");
}
NS_IMETHOD_(void) DeleteCycleCollectable(void*) override
{
MOZ_ASSERT(false, "Can't directly delete a cycle collectable GC thing");
}
NS_IMETHOD TraverseNative(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
override;
NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(JSZoneParticipant)
};
class IncrementalFinalizeRunnable;
// 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;
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;
bool mAnyManual; // true if any slice of the CC was manually triggered, or at shutdown.
uint32_t mVisitedRefCounted;
uint32_t mVisitedGCed;
uint32_t mFreedRefCounted;
uint32_t mFreedGCed;
uint32_t mFreedJSZones;
uint32_t mNumSlices;
};
class CycleCollectedJSContext
{
friend class JSGCThingParticipant;
friend class JSZoneParticipant;
friend class IncrementalFinalizeRunnable;
protected:
CycleCollectedJSContext();
virtual ~CycleCollectedJSContext();
MOZ_IS_CLASS_INIT
nsresult Initialize(JSRuntime* aParentRuntime,
uint32_t aMaxBytes,
uint32_t aMaxNurseryBytes);
size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
void UnmarkSkippableJSHolders();
virtual void
TraverseAdditionalNativeRoots(nsCycleCollectionNoteRootCallback& aCb) {}
virtual void TraceAdditionalNativeGrayRoots(JSTracer* aTracer) {}
virtual void CustomGCCallback(JSGCStatus aStatus) {}
virtual void CustomOutOfMemoryCallback() {}
virtual void CustomLargeAllocationFailureCallback() {}
std::queue<nsCOMPtr<nsIRunnable>> mPromiseMicroTaskQueue;
std::queue<nsCOMPtr<nsIRunnable>> mDebuggerPromiseMicroTaskQueue;
private:
void
DescribeGCThing(bool aIsMarked, JS::GCCellPtr aThing,
nsCycleCollectionTraversalCallback& aCb) const;
virtual bool
DescribeCustomObjects(JSObject* aObject, const js::Class* aClasp,
char (&aName)[72]) const
{
return false; // We did nothing.
}
void
NoteGCThingJSChildren(JS::GCCellPtr aThing,
nsCycleCollectionTraversalCallback& aCb) const;
void
NoteGCThingXPCOMChildren(const js::Class* aClasp, JSObject* aObj,
nsCycleCollectionTraversalCallback& aCb) const;
virtual bool
NoteCustomGCThingXPCOMChildren(const js::Class* aClasp, JSObject* aObj,
nsCycleCollectionTraversalCallback& aCb) const
{
return false; // We did nothing.
}
enum TraverseSelect {
TRAVERSE_CPP,
TRAVERSE_FULL
};
void
TraverseGCThing(TraverseSelect aTs, JS::GCCellPtr aThing,
nsCycleCollectionTraversalCallback& aCb);
void
TraverseZone(JS::Zone* aZone, nsCycleCollectionTraversalCallback& aCb);
static void
TraverseObjectShim(void* aData, JS::GCCellPtr aThing);
void TraverseNativeRoots(nsCycleCollectionNoteRootCallback& aCb);
static void TraceBlackJS(JSTracer* aTracer, void* aData);
static void TraceGrayJS(JSTracer* aTracer, void* aData);
static void GCCallback(JSContext* aContext, JSGCStatus aStatus, void* aData);
static void GCSliceCallback(JSContext* aContext, JS::GCProgress aProgress,
const JS::GCDescription& aDesc);
static void GCNurseryCollectionCallback(JSContext* aContext,
JS::GCNurseryProgress aProgress,
JS::gcreason::Reason aReason);
static void OutOfMemoryCallback(JSContext* aContext, void* aData);
static void LargeAllocationFailureCallback(void* aData);
/**
* Callback for reporting external string memory.
*/
static size_t SizeofExternalStringCallback(JSString* aStr,
mozilla::MallocSizeOf aMallocSizeOf);
static bool ContextCallback(JSContext* aCx, unsigned aOperation,
void* aData);
static JSObject* GetIncumbentGlobalCallback(JSContext* aCx);
static bool EnqueuePromiseJobCallback(JSContext* aCx,
JS::HandleObject aJob,
JS::HandleObject aAllocationSite,
JS::HandleObject aIncumbentGlobal,
void* aData);
static void PromiseRejectionTrackerCallback(JSContext* aCx,
JS::HandleObject aPromise,
PromiseRejectionHandlingState state,
void* aData);
virtual void TraceNativeBlackRoots(JSTracer* aTracer) { };
void TraceNativeGrayRoots(JSTracer* aTracer);
void AfterProcessMicrotask(uint32_t aRecursionDepth);
public:
void ProcessStableStateQueue();
private:
void ProcessMetastableStateQueue(uint32_t aRecursionDepth);
public:
enum DeferredFinalizeType {
FinalizeIncrementally,
FinalizeNow,
};
void FinalizeDeferredThings(DeferredFinalizeType aType);
// Two conditions, JSOutOfMemory and JSLargeAllocationFailure, are noted in
// crash reports. Here are the values that can appear in the reports:
enum class OOMState : uint32_t {
// The condition has never happened. No entry appears in the crash report.
OK,
// We are currently reporting the given condition.
//
// Suppose a crash report contains "JSLargeAllocationFailure:
// Reporting". This means we crashed while executing memory-pressure
// observers, trying to shake loose some memory. The large allocation in
// question did not return null: it is still on the stack. Had we not
// crashed, it would have been retried.
Reporting,
// The condition has been reported since the last GC.
//
// If a crash report contains "JSOutOfMemory: Reported", that means a small
// allocation failed, and then we crashed, probably due to buggy
// error-handling code that ran after allocation returned null.
//
// This contrasts with "Reporting" which means that no error-handling code
// had executed yet.
Reported,
// The condition has happened, but a GC cycle ended since then.
//
// GC is taken as a proxy for "we've been banging on the heap a good bit
// now and haven't crashed; the OOM was probably handled correctly".
Recovered
};
private:
void AnnotateAndSetOutOfMemory(OOMState* aStatePtr, OOMState aNewState);
void OnGC(JSGCStatus aStatus);
void OnOutOfMemory();
void OnLargeAllocationFailure();
public:
void AddJSHolder(void* aHolder, nsScriptObjectTracer* aTracer);
void RemoveJSHolder(void* aHolder);
#ifdef DEBUG
bool IsJSHolder(void* aHolder);
void AssertNoObjectsToTrace(void* aPossibleJSHolder);
#endif
already_AddRefed<nsIException> GetPendingException() const;
void SetPendingException(nsIException* aException);
std::queue<nsCOMPtr<nsIRunnable>>& GetPromiseMicroTaskQueue();
std::queue<nsCOMPtr<nsIRunnable>>& GetDebuggerPromiseMicroTaskQueue();
nsCycleCollectionParticipant* GCThingParticipant();
nsCycleCollectionParticipant* ZoneParticipant();
nsresult TraverseRoots(nsCycleCollectionNoteRootCallback& aCb);
virtual bool UsefulToMergeZones() const;
void FixWeakMappingGrayBits() const;
bool AreGCGrayBitsValid() const;
void GarbageCollect(uint32_t aReason) const;
void NurseryWrapperAdded(nsWrapperCache* aCache);
void NurseryWrapperPreserved(JSObject* aWrapper);
void JSObjectsTenured();
void DeferredFinalize(DeferredFinalizeAppendFunction aAppendFunc,
DeferredFinalizeFunction aFunc,
void* aThing);
void DeferredFinalize(nsISupports* aSupports);
void DumpJSHeap(FILE* aFile);
virtual void PrepareForForgetSkippable() = 0;
virtual void BeginCycleCollectionCallback() = 0;
virtual void EndCycleCollectionCallback(CycleCollectorResults& aResults) = 0;
virtual void DispatchDeferredDeletion(bool aContinuation, bool aPurge = false) = 0;
JSContext* Context() const
{
MOZ_ASSERT(mJSContext);
return mJSContext;
}
JS::RootingContext* RootingCx() const
{
MOZ_ASSERT(mJSContext);
return JS::RootingContext::get(mJSContext);
}
bool MicroTaskCheckpointDisabled() const
{
return mDisableMicroTaskCheckpoint;
}
void DisableMicroTaskCheckpoint(bool aDisable)
{
mDisableMicroTaskCheckpoint = aDisable;
}
class MOZ_RAII AutoDisableMicroTaskCheckpoint
{
public:
AutoDisableMicroTaskCheckpoint()
: mCCJSCX(CycleCollectedJSContext::Get())
{
mOldValue = mCCJSCX->MicroTaskCheckpointDisabled();
mCCJSCX->DisableMicroTaskCheckpoint(true);
}
~AutoDisableMicroTaskCheckpoint()
{
mCCJSCX->DisableMicroTaskCheckpoint(mOldValue);
}
CycleCollectedJSContext* mCCJSCX;
bool mOldValue;
};
protected:
JSContext* MaybeContext() const { return mJSContext; }
public:
// nsThread entrypoints
virtual void BeforeProcessTask(bool aMightBlock) { };
virtual void AfterProcessTask(uint32_t aRecursionDepth);
// microtask processor entry point
void AfterProcessMicrotask();
uint32_t RecursionDepth();
// Run in stable state (call through nsContentUtils)
void RunInStableState(already_AddRefed<nsIRunnable>&& aRunnable);
// This isn't in the spec at all yet, but this gets the behavior we want for IDB.
// Runs after the current microtask completes.
void RunInMetastableState(already_AddRefed<nsIRunnable>&& aRunnable);
// Get the current thread's CycleCollectedJSContext. Returns null if there
// isn't one.
static CycleCollectedJSContext* Get();
// Add aZone to the set of zones waiting for a GC.
void AddZoneWaitingForGC(JS::Zone* aZone)
{
mZonesWaitingForGC.PutEntry(aZone);
}
// Prepare any zones for GC that have been passed to AddZoneWaitingForGC()
// since the last GC or since the last call to PrepareWaitingZonesForGC(),
// whichever was most recent. If there were no such zones, prepare for a
// full GC.
void PrepareWaitingZonesForGC();
// Queue an async microtask to the current main or worker thread.
virtual void DispatchToMicroTask(already_AddRefed<nsIRunnable> aRunnable);
// 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;
private:
JSGCThingParticipant mGCThingCycleCollectorGlobal;
JSZoneParticipant mJSZoneCycleCollectorGlobal;
JSContext* mJSContext;
JS::GCSliceCallback mPrevGCSliceCallback;
JS::GCNurseryCollectionCallback mPrevGCNurseryCollectionCallback;
nsDataHashtable<nsPtrHashKey<void>, nsScriptObjectTracer*> mJSHolders;
typedef nsDataHashtable<nsFuncPtrHashKey<DeferredFinalizeFunction>, void*>
DeferredFinalizerTable;
DeferredFinalizerTable mDeferredFinalizerTable;
RefPtr<IncrementalFinalizeRunnable> mFinalizeRunnable;
nsCOMPtr<nsIException> mPendingException;
nsThread* mOwningThread; // Manual refcounting to avoid include hell.
struct RunInMetastableStateData
{
nsCOMPtr<nsIRunnable> mRunnable;
uint32_t mRecursionDepth;
};
nsTArray<nsCOMPtr<nsIRunnable>> mStableStateEvents;
nsTArray<RunInMetastableStateData> mMetastableStateEvents;
uint32_t mBaseRecursionDepth;
bool mDoingStableStates;
bool mDisableMicroTaskCheckpoint;
OOMState mOutOfMemoryState;
OOMState mLargeAllocationFailureState;
static const size_t kSegmentSize = 512;
SegmentedVector<nsWrapperCache*, kSegmentSize, InfallibleAllocPolicy>
mNurseryObjects;
SegmentedVector<JS::PersistentRooted<JSObject*>, kSegmentSize,
InfallibleAllocPolicy>
mPreservedNurseryObjects;
nsTHashtable<nsPtrHashKey<JS::Zone>> mZonesWaitingForGC;
struct EnvironmentPreparer : public js::ScriptEnvironmentPreparer {
void invoke(JS::HandleObject scope, Closure& closure) override;
};
EnvironmentPreparer mEnvironmentPreparer;
};
void TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer);
// Returns true if the JS::TraceKind is one the cycle collector cares about.
inline bool AddToCCKind(JS::TraceKind aKind)
{
return aKind == JS::TraceKind::Object || aKind == JS::TraceKind::Script || aKind == JS::TraceKind::Scope;
}
bool
GetBuildId(JS::BuildIdCharVector* aBuildID);
} // namespace mozilla
#endif // mozilla_CycleCollectedJSContext_h__