| /* |
| * Copyright (C) 2007, 2008, 2010 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. |
| * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of |
| * its contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE 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 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. |
| * |
| * |
| * Note: The implementations of InterlockedIncrement and InterlockedDecrement are based |
| * on atomic_increment and atomic_exchange_and_add from the Boost C++ Library. The license |
| * is virtually identical to the Apple license above but is included here for completeness. |
| * |
| * Boost Software License - Version 1.0 - August 17th, 2003 |
| * |
| * Permission is hereby granted, free of charge, to any person or organization |
| * obtaining a copy of the software and accompanying documentation covered by |
| * this license (the "Software") to use, reproduce, display, distribute, |
| * execute, and transmit the Software, and to prepare derivative works of the |
| * Software, and to permit third-parties to whom the Software is furnished to |
| * do so, all subject to the following: |
| * |
| * The copyright notices in the Software and this entire statement, including |
| * the above license grant, this restriction and the following disclaimer, |
| * must be included in all copies of the Software, in whole or in part, and |
| * all derivative works of the Software, unless such copies or derivative |
| * works are solely in the form of machine-executable object code generated by |
| * a source language processor. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT |
| * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE |
| * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, |
| * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| * DEALINGS IN THE SOFTWARE. |
| */ |
| |
| #ifndef ThreadSafeRefCounted_h |
| #define ThreadSafeRefCounted_h |
| |
| #include "Platform.h" |
| |
| #include <wtf/Atomics.h> |
| #include <wtf/ThreadingPrimitives.h> |
| |
| namespace WTF { |
| |
| class ThreadSafeRefCountedBase { |
| WTF_MAKE_NONCOPYABLE(ThreadSafeRefCountedBase); |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| ThreadSafeRefCountedBase(int initialRefCount = 1) |
| : m_refCount(initialRefCount) |
| { |
| } |
| |
| void ref() |
| { |
| #if USE(LOCKFREE_THREADSAFEREFCOUNTED) |
| atomicIncrement(&m_refCount); |
| #else |
| MutexLocker locker(m_mutex); |
| ++m_refCount; |
| #endif |
| } |
| |
| bool hasOneRef() |
| { |
| return refCount() == 1; |
| } |
| |
| int refCount() const |
| { |
| #if !USE(LOCKFREE_THREADSAFEREFCOUNTED) |
| MutexLocker locker(m_mutex); |
| #endif |
| return static_cast<int const volatile &>(m_refCount); |
| } |
| |
| protected: |
| // Returns whether the pointer should be freed or not. |
| bool derefBase() |
| { |
| #if USE(LOCKFREE_THREADSAFEREFCOUNTED) |
| if (atomicDecrement(&m_refCount) <= 0) |
| return true; |
| #else |
| int refCount; |
| { |
| MutexLocker locker(m_mutex); |
| --m_refCount; |
| refCount = m_refCount; |
| } |
| if (refCount <= 0) |
| return true; |
| #endif |
| return false; |
| } |
| |
| private: |
| template<class T> |
| friend class CrossThreadRefCounted; |
| |
| int m_refCount; |
| #if !USE(LOCKFREE_THREADSAFEREFCOUNTED) |
| mutable Mutex m_mutex; |
| #endif |
| }; |
| |
| template<class T> class ThreadSafeRefCounted : public ThreadSafeRefCountedBase { |
| public: |
| void deref() |
| { |
| if (derefBase()) |
| delete static_cast<T*>(this); |
| } |
| |
| protected: |
| ThreadSafeRefCounted() |
| { |
| } |
| }; |
| |
| } // namespace WTF |
| |
| using WTF::ThreadSafeRefCounted; |
| |
| #endif // ThreadSafeRefCounted_h |