1 /* 2 * Copyright (C) 2007, 2008, 2010 Apple Inc. All rights reserved. 3 * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com) 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of 15 * its contributors may be used to endorse or promote products derived 16 * from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY 19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 21 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY 22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #ifndef ThreadSafeRefCounted_h 31 #define ThreadSafeRefCounted_h 32 33 #include "wtf/Atomics.h" 34 #include "wtf/DynamicAnnotations.h" 35 #include "wtf/FastAllocBase.h" 36 #include "wtf/Noncopyable.h" 37 #include "wtf/WTFExport.h" 38 39 namespace WTF { 40 41 class WTF_EXPORT ThreadSafeRefCountedBase { 42 WTF_MAKE_NONCOPYABLE(ThreadSafeRefCountedBase); 43 WTF_MAKE_FAST_ALLOCATED; 44 public: 45 ThreadSafeRefCountedBase(int initialRefCount = 1) m_refCount(initialRefCount)46 : m_refCount(initialRefCount) 47 { 48 } 49 ref()50 void ref() 51 { 52 atomicIncrement(&m_refCount); 53 } 54 hasOneRef()55 bool hasOneRef() 56 { 57 return refCount() == 1; 58 } 59 refCount()60 int refCount() const 61 { 62 return static_cast<int const volatile &>(m_refCount); 63 } 64 65 protected: 66 // Returns whether the pointer should be freed or not. derefBase()67 bool derefBase() 68 { 69 WTF_ANNOTATE_HAPPENS_BEFORE(&m_refCount); 70 if (atomicDecrement(&m_refCount) <= 0) { 71 WTF_ANNOTATE_HAPPENS_AFTER(&m_refCount); 72 return true; 73 } 74 return false; 75 } 76 77 private: 78 int m_refCount; 79 }; 80 81 template<class T> class ThreadSafeRefCounted : public ThreadSafeRefCountedBase { 82 public: deref()83 void deref() 84 { 85 if (derefBase()) 86 delete static_cast<T*>(this); 87 } 88 89 protected: ThreadSafeRefCounted()90 ThreadSafeRefCounted() 91 { 92 } 93 }; 94 95 } // namespace WTF 96 97 using WTF::ThreadSafeRefCounted; 98 99 #endif // ThreadSafeRefCounted_h 100