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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 js_RefCounted_h
#define js_RefCounted_h
#include "mozilla/Atomics.h"
#include "mozilla/RefCountType.h"
#include "js/Utility.h"
// These types implement the same interface as mozilla::(Atomic)RefCounted and
// must be used instead of mozilla::(Atomic)RefCounted for everything in
// SpiderMonkey. There are two reasons:
// - Release() needs to call js_delete, not delete
// - SpiderMonkey does not have MOZILLA_INTERNAL_API defined which can lead
// to ODR violations that show up as spurious leak reports when ref-counted
// types are allocated by SpiderMonkey and released by Gecko (or vice versa).
namespace js {
template <typename T>
class RefCounted {
static const MozRefCountType DEAD = 0xffffdead;
protected:
RefCounted() : mRefCnt(0) {}
~RefCounted() { MOZ_ASSERT(mRefCnt == DEAD); }
public:
void AddRef() const {
MOZ_ASSERT(int32_t(mRefCnt) >= 0);
++mRefCnt;
}
void Release() const {
MOZ_ASSERT(int32_t(mRefCnt) > 0);
MozRefCountType cnt = --mRefCnt;
if (0 == cnt) {
#ifdef DEBUG
mRefCnt = DEAD;
#endif
js_delete(const_cast<T*>(static_cast<const T*>(this)));
}
}
private:
mutable MozRefCountType mRefCnt;
};
template <typename T>
class AtomicRefCounted {
// On 64-bit systems, if the refcount type is small (say, 32 bits), there's
// a risk that it could overflow. So require it to be large enough.
static_assert(sizeof(MozRefCountType) == sizeof(uintptr_t),
"You're at risk for ref count overflow.");
static const MozRefCountType DEAD = ~MozRefCountType(0xffff) | 0xdead;
protected:
AtomicRefCounted() = default;
~AtomicRefCounted() { MOZ_ASSERT(mRefCnt == DEAD); }
public:
void AddRef() const {
++mRefCnt;
MOZ_ASSERT(mRefCnt != DEAD);
}
void Release() const {
MOZ_ASSERT(mRefCnt != 0);
MozRefCountType cnt = --mRefCnt;
if (0 == cnt) {
#ifdef DEBUG
mRefCnt = DEAD;
#endif
js_delete(const_cast<T*>(static_cast<const T*>(this)));
}
}
bool hasOneRef() const {
MOZ_ASSERT(mRefCnt > 0);
return mRefCnt == 1;
}
private:
mutable mozilla::Atomic<MozRefCountType> mRefCnt{0};
};
} // namespace js
#endif /* js_RefCounted_h */
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