/* * Copyright (C) 2007, 2008, 2010, 2013, 2014 Apple Inc. All rights reserved. * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com) * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #pragma once #include <atomic> #include <wtf/FastMalloc.h> #include <wtf/MainThread.h> #include <wtf/Noncopyable.h> namespace WTF { class ThreadSafeRefCountedBase { WTF_MAKE_NONCOPYABLE(ThreadSafeRefCountedBase); WTF_MAKE_FAST_ALLOCATED; public: ThreadSafeRefCountedBase() = default; void ref() const { ++m_refCount; } bool hasOneRef() const { return refCount() == 1; } unsigned refCount() const { return m_refCount; } protected: // Returns whether the pointer should be freed or not. bool derefBase() const { return !--m_refCount; } private: mutable std::atomic<unsigned> m_refCount { 1 }; }; enum class DestructionThread { Any, Main }; template<class T, DestructionThread destructionThread = DestructionThread::Any> class ThreadSafeRefCounted : public ThreadSafeRefCountedBase { public: void deref() const { if (!derefBase()) return; if (destructionThread == DestructionThread::Any || isMainThread()) { delete static_cast<const T*>(this); return; } callOnMainThread([this] { delete static_cast<const T*>(this); }); } protected: ThreadSafeRefCounted() = default; }; } // namespace WTF using WTF::ThreadSafeRefCounted;