gecko-dev/xpcom/base/CycleCollectedJSRuntime.h
2015-01-26 07:22:08 +09:00

330 lines
9.6 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_CycleCollectedJSRuntime_h__
#define mozilla_CycleCollectedJSRuntime_h__
#include "mozilla/MemoryReporting.h"
#include "jsapi.h"
#include "nsCycleCollector.h"
#include "nsCycleCollectionParticipant.h"
#include "nsDataHashtable.h"
#include "nsHashKeys.h"
#include "nsTArray.h"
class nsCycleCollectionNoteRootCallback;
class nsIException;
class nsIRunnable;
namespace js {
struct Class;
}
namespace mozilla {
class JSGCThingParticipant: public nsCycleCollectionParticipant
{
public:
NS_IMETHOD_(void) Root(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Don't call Root on GC things");
}
NS_IMETHOD_(void) Unlink(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Don't call Unlink on GC things, as they may be dead");
}
NS_IMETHOD_(void) Unroot(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Don't call Unroot on GC things, as they may be dead");
}
NS_IMETHOD_(void) DeleteCycleCollectable(void* aPtr) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Can't directly delete a cycle collectable GC thing");
}
NS_IMETHOD Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
MOZ_OVERRIDE;
};
class JSZoneParticipant : public nsCycleCollectionParticipant
{
public:
MOZ_CONSTEXPR JSZoneParticipant(): nsCycleCollectionParticipant()
{
}
NS_IMETHOD_(void) Root(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Don't call Root on GC things");
}
NS_IMETHOD_(void) Unlink(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Don't call Unlink on GC things, as they may be dead");
}
NS_IMETHOD_(void) Unroot(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Don't call Unroot on GC things, as they may be dead");
}
NS_IMETHOD_(void) DeleteCycleCollectable(void*) MOZ_OVERRIDE
{
MOZ_ASSERT(false, "Can't directly delete a cycle collectable GC thing");
}
NS_IMETHOD Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
MOZ_OVERRIDE;
};
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;
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;
uint32_t mVisitedRefCounted;
uint32_t mVisitedGCed;
uint32_t mFreedRefCounted;
uint32_t mFreedGCed;
uint32_t mFreedJSZones;
uint32_t mNumSlices;
};
class CycleCollectedJSRuntime
{
friend class JSGCThingParticipant;
friend class JSZoneParticipant;
friend class IncrementalFinalizeRunnable;
protected:
CycleCollectedJSRuntime(JSRuntime* aParentRuntime,
uint32_t aMaxBytes,
uint32_t aMaxNurseryBytes);
virtual ~CycleCollectedJSRuntime();
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() {}
virtual bool CustomContextCallback(JSContext* aCx, unsigned aOperation)
{
return true; // Don't block context creation.
}
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(JSRuntime* aRuntime, JSGCStatus aStatus, void* aData);
static void OutOfMemoryCallback(JSContext* aContext, void* aData);
static void LargeAllocationFailureCallback(void* aData);
static bool ContextCallback(JSContext* aCx, unsigned aOperation,
void* aData);
virtual void TraceNativeBlackRoots(JSTracer* aTracer) { };
void TraceNativeGrayRoots(JSTracer* aTracer);
enum DeferredFinalizeType {
FinalizeIncrementally,
FinalizeNow,
};
void FinalizeDeferredThings(DeferredFinalizeType aType);
public:
// 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);
nsTArray<nsRefPtr<nsIRunnable>>& GetPromiseMicroTaskQueue();
nsCycleCollectionParticipant* GCThingParticipant();
nsCycleCollectionParticipant* ZoneParticipant();
nsresult TraverseRoots(nsCycleCollectionNoteRootCallback& aCb);
bool UsefulToMergeZones() const;
void FixWeakMappingGrayBits() const;
bool AreGCGrayBitsValid() const;
void GarbageCollect(uint32_t aReason) const;
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) = 0;
JSRuntime* Runtime() const
{
MOZ_ASSERT(mJSRuntime);
return mJSRuntime;
}
// Get the current thread's CycleCollectedJSRuntime. Returns null if there
// isn't one.
static CycleCollectedJSRuntime* Get();
private:
JSGCThingParticipant mGCThingCycleCollectorGlobal;
JSZoneParticipant mJSZoneCycleCollectorGlobal;
JSRuntime* mJSRuntime;
nsDataHashtable<nsPtrHashKey<void>, nsScriptObjectTracer*> mJSHolders;
nsTArray<nsISupports*> mDeferredSupports;
typedef nsDataHashtable<nsFuncPtrHashKey<DeferredFinalizeFunction>, void*>
DeferredFinalizerTable;
DeferredFinalizerTable mDeferredFinalizerTable;
nsRefPtr<IncrementalFinalizeRunnable> mFinalizeRunnable;
nsCOMPtr<nsIException> mPendingException;
nsTArray<nsRefPtr<nsIRunnable>> mPromiseMicroTaskQueue;
OOMState mOutOfMemoryState;
OOMState mLargeAllocationFailureState;
};
void TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer);
// Returns true if the JSGCTraceKind is one the cycle collector cares about.
inline bool AddToCCKind(JSGCTraceKind aKind)
{
return aKind == JSTRACE_OBJECT || aKind == JSTRACE_SCRIPT;
}
} // namespace mozilla
#endif // mozilla_CycleCollectedJSRuntime_h__