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 28 namespace WebCore { 29 30 #ifndef NDEBUG 31 template<typename NodeType> class TreeShared; 32 template<typename NodeType> void adopted(TreeShared<NodeType>*); 33 #endif 34 35 template<typename NodeType> class TreeShared { 36 WTF_MAKE_NONCOPYABLE(TreeShared); 37 protected: 38 TreeShared() 39 : m_refCount(1) 40 #ifndef NDEBUG 41 , m_deletionHasBegun(false) 42 , m_inRemovedLastRefFunction(false) 43 , m_adoptionIsRequired(true) 44 #endif 45 { 46 ASSERT(isMainThread()); 47 } 48 49 ~TreeShared() 50 { 51 ASSERT(isMainThread()); 52 ASSERT(!m_refCount); 53 ASSERT(m_deletionHasBegun); 54 ASSERT(!m_adoptionIsRequired); 55 } 56 57 public: 58 void ref() 59 { 60 ASSERT(isMainThread()); 61 ASSERT(!m_deletionHasBegun); 62 ASSERT(!m_inRemovedLastRefFunction); 63 ASSERT(!m_adoptionIsRequired); 64 ++m_refCount; 65 } 66 67 void deref() 68 { 69 ASSERT(isMainThread()); 70 ASSERT(m_refCount >= 0); 71 ASSERT(!m_deletionHasBegun); 72 ASSERT(!m_inRemovedLastRefFunction); 73 ASSERT(!m_adoptionIsRequired); 74 NodeType* thisNode = static_cast<NodeType*>(this); 75 if (--m_refCount <= 0 && !thisNode->hasTreeSharedParent()) { 76 #ifndef NDEBUG 77 m_inRemovedLastRefFunction = true; 78 #endif 79 thisNode->removedLastRef(); 80 } 81 } 82 83 bool hasOneRef() const 84 { 85 ASSERT(!m_deletionHasBegun); 86 ASSERT(!m_inRemovedLastRefFunction); 87 return m_refCount == 1; 88 } 89 90 int refCount() const 91 { 92 return m_refCount; 93 } 94 95 private: 96 int m_refCount; 97 98 #ifndef NDEBUG 99 public: 100 bool m_deletionHasBegun; 101 bool m_inRemovedLastRefFunction; 102 private: 103 friend void adopted<>(TreeShared<NodeType>*); 104 bool m_adoptionIsRequired; 105 #endif 106 }; 107 108 #ifndef NDEBUG 109 110 template<typename NodeType> inline void adopted(TreeShared<NodeType>* object) 111 { 112 if (!object) 113 return; 114 ASSERT(!object->m_deletionHasBegun); 115 ASSERT(!object->m_inRemovedLastRefFunction); 116 object->m_adoptionIsRequired = false; 117 } 118 119 #endif 120 121 } 122 123 #endif // TreeShared.h 124