зеркало из https://github.com/mozilla/gecko-dev.git
92 строки
2.4 KiB
C++
92 строки
2.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* vim: set ts=8 sts=2 et sw=2 tw=80:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef js_RefCounted_h
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#define js_RefCounted_h
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#include "mozilla/Atomics.h"
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#include "mozilla/RefCountType.h"
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#include "js/Utility.h"
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// These types implement the same interface as mozilla::(Atomic)RefCounted and
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// must be used instead of mozilla::(Atomic)RefCounted for everything in
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// SpiderMonkey. There are two reasons:
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// - Release() needs to call js_delete, not delete
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// - SpiderMonkey does not have MOZILLA_INTERNAL_API defined which can lead
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// to ODR violations that show up as spurious leak reports when ref-counted
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// types are allocated by SpiderMonkey and released by Gecko (or vice versa).
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namespace js {
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template <typename T>
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class RefCounted {
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static const MozRefCountType DEAD = 0xffffdead;
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protected:
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RefCounted() : mRefCnt(0) {}
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~RefCounted() { MOZ_ASSERT(mRefCnt == DEAD); }
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public:
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void AddRef() const {
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MOZ_ASSERT(int32_t(mRefCnt) >= 0);
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++mRefCnt;
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}
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void Release() const {
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MOZ_ASSERT(int32_t(mRefCnt) > 0);
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MozRefCountType cnt = --mRefCnt;
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if (0 == cnt) {
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#ifdef DEBUG
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mRefCnt = DEAD;
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#endif
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js_delete(const_cast<T*>(static_cast<const T*>(this)));
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}
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}
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private:
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mutable MozRefCountType mRefCnt;
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};
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template <typename T>
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class AtomicRefCounted {
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// On 64-bit systems, if the refcount type is small (say, 32 bits), there's
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// a risk that it could overflow. So require it to be large enough.
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static_assert(sizeof(MozRefCountType) == sizeof(uintptr_t),
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"You're at risk for ref count overflow.");
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static const MozRefCountType DEAD = ~MozRefCountType(0xffff) | 0xdead;
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protected:
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AtomicRefCounted() : mRefCnt(0) {}
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~AtomicRefCounted() { MOZ_ASSERT(mRefCnt == DEAD); }
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public:
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void AddRef() const {
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++mRefCnt;
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MOZ_ASSERT(mRefCnt != DEAD);
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}
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void Release() const {
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MOZ_ASSERT(mRefCnt != 0);
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MozRefCountType cnt = --mRefCnt;
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if (0 == cnt) {
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#ifdef DEBUG
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mRefCnt = DEAD;
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#endif
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js_delete(const_cast<T*>(static_cast<const T*>(this)));
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}
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}
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private:
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mutable mozilla::Atomic<MozRefCountType> mRefCnt;
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};
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} // namespace js
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#endif /* js_RefCounted_h */
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