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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
#ifndef gc_GCContext_h
#define gc_GCContext_h
#include "mozilla/Assertions.h" // MOZ_ASSERT
#include "mozilla/ThreadLocal.h"
#include "jspubtd.h"
#include "jstypes.h" // JS_PUBLIC_API
#include "gc/GCEnum.h" // js::MemoryUse
#include "jit/ExecutableAllocator.h" // jit::JitPoisonRangeVector
#include "js/Utility.h" // js_free
struct JS_PUBLIC_API JSRuntime;
namespace js {
class AutoTouchingGrayThings;
namespace gc {
class AutoSetThreadGCUse;
class AutoSetThreadIsSweeping;
enum class GCUse {
// This thread is not running in the garbage collector.
None,
// This thread is currently collecting. Used when no finer detail is known.
Unspecified,
// This thread is currently marking GC things. This thread could be the main
// thread or a helper thread doing sweep-marking.
Marking,
// This thread is currently sweeping GC things. This thread could be the
// main thread or a helper thread while the main thread is running the
// mutator.
Sweeping,
// Whether this thread is currently finalizing GC things. This thread could
// be the main thread or a helper thread doing finalization while the main
// thread is running the mutator.
Finalizing
};
} // namespace gc
} // namespace js
namespace JS {
/*
* GCContext is by GC operations that can run on or off the main thread.
*
* Its main function is to provide methods to free memory and update memory
* accounting. For convenience, it also has delete_ convenience methods that
* also call destructors.
*
* It is passed to finalizers and other sweep-phase hooks as JSContext is not
* available off the main thread.
*/
class GCContext {
using Cell = js::gc::Cell;
using MemoryUse = js::MemoryUse;
JSRuntime* const runtime_;
js::jit::JitPoisonRangeVector jitPoisonRanges;
// Which part of the garbage collector this context is running at the moment.
js::gc::GCUse gcUse_ = js::gc::GCUse::None;
friend class js::gc::AutoSetThreadGCUse;
friend class js::gc::AutoSetThreadIsSweeping;
#ifdef DEBUG
// The specific zone currently being swept, if any.
Zone* gcSweepZone_ = nullptr;
// Whether this thread is currently manipulating possibly-gray GC things.
size_t isTouchingGrayThings_ = false;
friend class js::AutoTouchingGrayThings;
#endif
public:
explicit GCContext(JSRuntime* maybeRuntime);
~GCContext();
JSRuntime* runtime() const {
MOZ_ASSERT(onMainThread());
return runtimeFromAnyThread();
}
JSRuntime* runtimeFromAnyThread() const {
MOZ_ASSERT(runtime_);
return runtime_;
}
js::gc::GCUse gcUse() const { return gcUse_; }
bool isCollecting() const { return gcUse() != js::gc::GCUse::None; }
bool isFinalizing() const { return gcUse_ == js::gc::GCUse::Finalizing; }
#ifdef DEBUG
bool onMainThread() const {
return js::CurrentThreadCanAccessRuntime(runtime_);
}
Zone* gcSweepZone() const { return gcSweepZone_; }
bool isTouchingGrayThings() const { return isTouchingGrayThings_; }
#endif
// Deprecated. Where possible, memory should be tracked against the owning GC
// thing by calling js::AddCellMemory and the memory freed with free_() below.
void freeUntracked(void* p) { js_free(p); }
// Free memory associated with a GC thing and update the memory accounting.
//
// The memory should have been associated with the GC thing using
// js::InitReservedSlot or js::InitObjectPrivate, or possibly
// js::AddCellMemory.
void free_(Cell* cell, void* p, size_t nbytes, MemoryUse use);
bool appendJitPoisonRange(const js::jit::JitPoisonRange& range) {
return jitPoisonRanges.append(range);
}
bool hasJitCodeToPoison() const { return !jitPoisonRanges.empty(); }
void poisonJitCode();
// Deprecated. Where possible, memory should be tracked against the owning GC
// thing by calling js::AddCellMemory and the memory freed with delete_()
// below.
template <class T>
void deleteUntracked(T* p) {
if (p) {
p->~T();
js_free(p);
}
}
// Delete a C++ object that was associated with a GC thing and update the
// memory accounting. The size is determined by the type T.
//
// The memory should have been associated with the GC thing using
// js::InitReservedSlot or js::InitObjectPrivate, or possibly
// js::AddCellMemory.
template <class T>
void delete_(Cell* cell, T* p, MemoryUse use) {
delete_(cell, p, sizeof(T), use);
}
// Delete a C++ object that was associated with a GC thing and update the
// memory accounting.
//
// The memory should have been associated with the GC thing using
// js::InitReservedSlot or js::InitObjectPrivate, or possibly
// js::AddCellMemory.
template <class T>
void delete_(Cell* cell, T* p, size_t nbytes, MemoryUse use) {
if (p) {
p->~T();
free_(cell, p, nbytes, use);
}
}
// Release a RefCounted object that was associated with a GC thing and update
// the memory accounting.
//
// The memory should have been associated with the GC thing using
// js::InitReservedSlot or js::InitObjectPrivate, or possibly
// js::AddCellMemory.
//
// This counts the memory once per association with a GC thing. It's not
// expected that the same object is associated with more than one GC thing in
// each zone. If this is the case then some other form of accounting would be
// more appropriate.
template <class T>
void release(Cell* cell, T* p, MemoryUse use) {
release(cell, p, sizeof(T), use);
}
// Release a RefCounted object and that was associated with a GC thing and
// update the memory accounting.
//
// The memory should have been associated with the GC thing using
// js::InitReservedSlot or js::InitObjectPrivate, or possibly
// js::AddCellMemory.
template <class T>
void release(Cell* cell, T* p, size_t nbytes, MemoryUse use);
// Update the memory accounting for a GC for memory freed by some other
// method.
void removeCellMemory(Cell* cell, size_t nbytes, MemoryUse use);
};
} // namespace JS
namespace js {
/* Thread Local Storage for storing the GCContext for a thread. */
extern MOZ_THREAD_LOCAL(JS::GCContext*) TlsGCContext;
inline JS::GCContext* MaybeGetGCContext() {
if (!TlsGCContext.init()) {
return nullptr;
}
return TlsGCContext.get();
}
class MOZ_RAII AutoTouchingGrayThings {
public:
#ifdef DEBUG
AutoTouchingGrayThings() { TlsGCContext.get()->isTouchingGrayThings_++; }
~AutoTouchingGrayThings() {
JS::GCContext* gcx = TlsGCContext.get();
MOZ_ASSERT(gcx->isTouchingGrayThings_);
gcx->isTouchingGrayThings_--;
}
#else
AutoTouchingGrayThings() {}
#endif
};
#ifdef DEBUG
inline bool CurrentThreadIsGCMarking() {
JS::GCContext* gcx = MaybeGetGCContext();
return gcx && gcx->gcUse() == gc::GCUse::Marking;
}
inline bool CurrentThreadIsGCSweeping() {
JS::GCContext* gcx = MaybeGetGCContext();
return gcx && gcx->gcUse() == gc::GCUse::Sweeping;
}
inline bool CurrentThreadIsGCFinalizing() {
JS::GCContext* gcx = MaybeGetGCContext();
return gcx && gcx->gcUse() == gc::GCUse::Finalizing;
}
inline bool CurrentThreadIsTouchingGrayThings() {
JS::GCContext* gcx = MaybeGetGCContext();
return gcx && gcx->isTouchingGrayThings();
}
inline bool CurrentThreadIsPerformingGC() {
JS::GCContext* gcx = MaybeGetGCContext();
return gcx && gcx->isCollecting();
}
#endif
} // namespace js
#endif // gc_GCContext_h