gecko-dev/xpcom/base/CycleCollectedJSRuntime.h

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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_CycleCollectedJSRuntime_h
#define mozilla_CycleCollectedJSRuntime_h
#include <queue>
#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/DeferredFinalize.h"
#include "mozilla/LinkedList.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 "nsTHashtable.h"
class nsCycleCollectionNoteRootCallback;
class nsIException;
class nsIRunnable;
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;
struct JSHolderInfo
{
void* mHolder;
nsScriptObjectTracer* mTracer;
};
class CycleCollectedJSRuntime
{
friend class JSGCThingParticipant;
friend class JSZoneParticipant;
friend class IncrementalFinalizeRunnable;
friend class CycleCollectedJSContext;
protected:
CycleCollectedJSRuntime(JSContext* aMainContext);
virtual ~CycleCollectedJSRuntime();
virtual void Shutdown(JSContext* cx);
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() {}
LinkedList<CycleCollectedJSContext>& Contexts()
{
return mContexts;
}
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);
/**
* Callback for reporting external string memory.
*/
static size_t SizeofExternalStringCallback(JSString* aStr,
mozilla::MallocSizeOf aMallocSizeOf);
static bool ContextCallback(JSContext* aCx, unsigned aOperation,
void* aData);
virtual void TraceNativeBlackRoots(JSTracer* aTracer) { };
void TraceNativeGrayRoots(JSTracer* aTracer);
public:
void FinalizeDeferredThings(CycleCollectedJSContext::DeferredFinalizeType aType);
virtual void PrepareForForgetSkippable() = 0;
virtual void BeginCycleCollectionCallback() = 0;
virtual void EndCycleCollectionCallback(CycleCollectorResults& aResults) = 0;
virtual void DispatchDeferredDeletion(bool aContinuation, bool aPurge = false) = 0;
// 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
};
void SetLargeAllocationFailure(OOMState aNewState);
void AnnotateAndSetOutOfMemory(OOMState* aStatePtr, OOMState aNewState);
void OnGC(JSContext* aContext, JSGCStatus aStatus);
void OnOutOfMemory();
void OnLargeAllocationFailure();
JSRuntime* Runtime() { return mJSRuntime; }
const JSRuntime* Runtime() const { return mJSRuntime; }
bool HasPendingIdleGCTask() const
{
// Idle GC task associates with JSRuntime.
MOZ_ASSERT_IF(mHasPendingIdleGCTask, Runtime());
return mHasPendingIdleGCTask;
}
void SetPendingIdleGCTask()
{
// Idle GC task associates with JSRuntime.
MOZ_ASSERT(Runtime());
mHasPendingIdleGCTask = true;
}
void ClearPendingIdleGCTask() { mHasPendingIdleGCTask = false; }
void RunIdleTimeGCTask()
{
if (HasPendingIdleGCTask()) {
JS::RunIdleTimeGCTask(Runtime());
ClearPendingIdleGCTask();
}
}
bool IsIdleGCTaskNeeded()
{
return !HasPendingIdleGCTask() && Runtime() && JS::IsIdleGCTaskNeeded(Runtime());
}
public:
void AddJSHolder(void* aHolder, nsScriptObjectTracer* aTracer);
void RemoveJSHolder(void* aHolder);
#ifdef DEBUG
bool IsJSHolder(void* aHolder);
void AssertNoObjectsToTrace(void* aPossibleJSHolder);
#endif
nsCycleCollectionParticipant* GCThingParticipant();
nsCycleCollectionParticipant* ZoneParticipant();
nsresult TraverseRoots(nsCycleCollectionNoteRootCallback& aCb);
virtual bool UsefulToMergeZones() const;
void FixWeakMappingGrayBits() const;
void CheckGrayBits() const;
bool AreGCGrayBitsValid() const;
void GarbageCollect(uint32_t aReason) const;
// This needs to be an nsWrapperCache, not a JSObject, because we need to know
// when our object gets moved. But we can't trace it (and hence update our
// storage), because we do not want to keep it alive. nsWrapperCache handles
// this for us via its "object moved" handling.
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);
// 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();
// Get the current thread's CycleCollectedJSRuntime. Returns null if there
// isn't one.
static CycleCollectedJSRuntime* Get();
void AddContext(CycleCollectedJSContext* aContext);
void RemoveContext(CycleCollectedJSContext* aContext);
#ifdef NIGHTLY_BUILD
bool GetRecentDevError(JSContext* aContext, JS::MutableHandle<JS::Value> aError);
void ClearRecentDevError();
#endif // defined(NIGHTLY_BUILD)
private:
LinkedList<CycleCollectedJSContext> mContexts;
JSGCThingParticipant mGCThingCycleCollectorGlobal;
JSZoneParticipant mJSZoneCycleCollectorGlobal;
JSRuntime* mJSRuntime;
bool mHasPendingIdleGCTask;
JS::GCSliceCallback mPrevGCSliceCallback;
JS::GCNurseryCollectionCallback mPrevGCNurseryCollectionCallback;
mozilla::TimeStamp mLatestNurseryCollectionStart;
SegmentedVector<JSHolderInfo, 1024, InfallibleAllocPolicy> mJSHolders;
nsDataHashtable<nsPtrHashKey<void>, JSHolderInfo*> mJSHolderMap;
typedef nsDataHashtable<nsFuncPtrHashKey<DeferredFinalizeFunction>, void*>
DeferredFinalizerTable;
DeferredFinalizerTable mDeferredFinalizerTable;
RefPtr<IncrementalFinalizeRunnable> mFinalizeRunnable;
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;
#ifdef DEBUG
bool mShutdownCalled;
#endif
#ifdef NIGHTLY_BUILD
// Implementation of the error interceptor.
// Built on nightly only to avoid any possible performance impact on release
struct ErrorInterceptor final : public JSErrorInterceptor {
virtual void interceptError(JSContext* cx, const JS::Value& val) override;
void Shutdown(JSRuntime* rt);
// Copy of the details of the exception.
// We store this rather than the exception itself to avoid dealing with complicated
// garbage-collection scenarios, e.g. a JSContext being killed while we still hold
// onto an exception thrown from it.
struct ErrorDetails {
nsString mFilename;
nsString mMessage;
nsString mStack;
JSExnType mType;
uint32_t mLine;
uint32_t mColumn;
};
// If we have encountered at least one developer error,
// the first error we have encountered. Otherwise, or
// if we have reset since the latest error, `None`.
Maybe<ErrorDetails> mThrownError;
};
ErrorInterceptor mErrorInterceptor;
#endif // defined(NIGHTLY_BUILD)
};
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 ||
aKind == JS::TraceKind::RegExpShared;
}
bool
GetBuildId(JS::BuildIdCharVector* aBuildID);
} // namespace mozilla
#endif // mozilla_CycleCollectedJSRuntime_h