1/* 2 * Copyright (C) 2006, 2007, 2009, 2010, 2012 Apple Inc. All rights reserved. 3 * 4 * This library is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Library General Public 6 * License as published by the Free Software Foundation; either 7 * version 2 of the License, or (at your option) any later version. 8 * 9 * This library is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * Library General Public License for more details. 13 * 14 * You should have received a copy of the GNU Library General Public License 15 * along with this library; see the file COPYING.LIB. If not, write to 16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 17 * Boston, MA 02110-1301, USA. 18 * 19 */ 20 21#ifndef TreeShared_h 22#define TreeShared_h 23 24#include <wtf/Assertions.h> 25#include <wtf/MainThread.h> 26#include <wtf/Noncopyable.h> 27 28namespace WebCore { 29 30#ifndef NDEBUG 31template<typename NodeType> class TreeShared; 32template<typename NodeType> void adopted(TreeShared<NodeType>*); 33#endif 34 35template<typename NodeType> class TreeShared { 36 WTF_MAKE_NONCOPYABLE(TreeShared); 37protected: 38 TreeShared() 39 : m_refCount(1) 40#ifndef NDEBUG 41 , m_adoptionIsRequired(true) 42#endif 43 { 44 ASSERT(isMainThread()); 45#ifndef NDEBUG 46 m_deletionHasBegun = false; 47 m_inRemovedLastRefFunction = false; 48#endif 49 } 50 51 ~TreeShared() 52 { 53 ASSERT(isMainThread()); 54 ASSERT(!m_refCount); 55 ASSERT(m_deletionHasBegun); 56 ASSERT(!m_adoptionIsRequired); 57 } 58 59public: 60 void ref() 61 { 62 ASSERT(isMainThread()); 63 ASSERT(!m_deletionHasBegun); 64 ASSERT(!m_inRemovedLastRefFunction); 65 ASSERT(!m_adoptionIsRequired); 66 ++m_refCount; 67 } 68 69 void deref() 70 { 71 ASSERT(isMainThread()); 72 ASSERT(m_refCount >= 0); 73 ASSERT(!m_deletionHasBegun); 74 ASSERT(!m_inRemovedLastRefFunction); 75 ASSERT(!m_adoptionIsRequired); 76 NodeType* thisNode = static_cast<NodeType*>(this); 77 if (--m_refCount <= 0 && !thisNode->hasTreeSharedParent()) { 78#ifndef NDEBUG 79 m_inRemovedLastRefFunction = true; 80#endif 81 thisNode->removedLastRef(); 82 } 83 } 84 85 bool hasOneRef() const 86 { 87 ASSERT(!m_deletionHasBegun); 88 ASSERT(!m_inRemovedLastRefFunction); 89 return m_refCount == 1; 90 } 91 92 int refCount() const 93 { 94 return m_refCount; 95 } 96 97#ifndef NDEBUG 98 bool m_deletionHasBegun; 99 bool m_inRemovedLastRefFunction; 100#endif 101 102private: 103#ifndef NDEBUG 104 friend void adopted<>(TreeShared<NodeType>*); 105#endif 106 107 int m_refCount; 108 109#ifndef NDEBUG 110 bool m_adoptionIsRequired; 111#endif 112}; 113 114#ifndef NDEBUG 115 116template<typename NodeType> inline void adopted(TreeShared<NodeType>* object) 117{ 118 if (!object) 119 return; 120 ASSERT(!object->m_deletionHasBegun); 121 ASSERT(!object->m_inRemovedLastRefFunction); 122 object->m_adoptionIsRequired = false; 123} 124 125#endif 126 127} 128 129#endif // TreeShared.h 130