blocxx
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00001 /******************************************************************************* 00002 * Copyright (C) 2005, Vintela, Inc. All rights reserved. 00003 * Copyright (C) 2006, Novell, Inc. All rights reserved. 00004 * 00005 * Redistribution and use in source and binary forms, with or without 00006 * modification, are permitted provided that the following conditions are met: 00007 * 00008 * * Redistributions of source code must retain the above copyright notice, 00009 * this list of conditions and the following disclaimer. 00010 * * Redistributions in binary form must reproduce the above copyright 00011 * notice, this list of conditions and the following disclaimer in the 00012 * documentation and/or other materials provided with the distribution. 00013 * * Neither the name of 00014 * Vintela, Inc., 00015 * nor Novell, Inc., 00016 * nor the names of its contributors or employees may be used to 00017 * endorse or promote products derived from this software without 00018 * specific prior written permission. 00019 * 00020 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 00021 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 00022 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 00023 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 00024 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 00025 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 00026 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 00027 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 00028 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 00029 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00030 * POSSIBILITY OF SUCH DAMAGE. 00031 *******************************************************************************/ 00032 00033 00038 // 00039 // Copyright (c) 2001, 2002 Peter Dimov 00040 // 00041 // Permission to copy, use, modify, sell and distribute this software 00042 // is granted provided this copyright notice appears in all copies. 00043 // This software is provided "as is" without express or implied 00044 // warranty, and with no claim as to its suitability for any purpose. 00045 // 00046 00047 #ifndef BLOCXX_COW_INTRUSIVE_COUNTABLE_BASE_HPP_INCLUDE_GUARD_ 00048 #define BLOCXX_COW_INTRUSIVE_COUNTABLE_BASE_HPP_INCLUDE_GUARD_ 00049 00050 #include "blocxx/BLOCXX_config.h" 00051 #include "blocxx/RefCount.hpp" 00052 00053 namespace BLOCXX_NAMESPACE 00054 { 00055 00072 class COWIntrusiveCountableBase; 00073 void COWIntrusiveReferenceAddRef(COWIntrusiveCountableBase * p); 00074 void COWIntrusiveReferenceRelease(COWIntrusiveCountableBase * p); 00075 bool COWIntrusiveReferenceUnique(COWIntrusiveCountableBase* p); 00076 template <typename T> T* COWIntrusiveReferenceClone(T* p); 00077 00078 class BLOCXX_COMMON_API COWIntrusiveCountableBase 00079 { 00080 private: 00081 RefCount m_usecount; 00082 00083 protected: 00087 COWIntrusiveCountableBase(COWIntrusiveCountableBase const &) 00088 : m_usecount(0) 00089 {} 00090 00096 COWIntrusiveCountableBase & operator=(COWIntrusiveCountableBase const &x) 00097 { 00098 // don't assign or change the ref count, since it won't be different. 00099 return *this; 00100 } 00101 00105 COWIntrusiveCountableBase(): m_usecount(0) 00106 { 00107 } 00108 00112 virtual ~COWIntrusiveCountableBase(); 00113 00117 RefCount getRefCount() const 00118 { 00119 return m_usecount; 00120 } 00121 00122 public: 00128 inline friend void COWIntrusiveReferenceAddRef(COWIntrusiveCountableBase * p) 00129 { 00130 p->m_usecount.inc(); 00131 } 00132 00140 inline friend void COWIntrusiveReferenceRelease(COWIntrusiveCountableBase * p) 00141 { 00142 if (p->m_usecount.decAndTest()) 00143 delete p; 00144 } 00145 00152 inline friend bool COWIntrusiveReferenceUnique(COWIntrusiveCountableBase* p) 00153 { 00154 return p->m_usecount.get() == 1; 00155 } 00156 00162 template <typename T> 00163 friend T* COWIntrusiveReferenceClone(T* p); 00164 }; 00165 00166 template <typename T> 00167 inline T* COWIntrusiveReferenceClone(T* p) 00168 { 00169 // this needs to happen first to avoid a race condition between 00170 // another thread deleting the object and this one making a copy. 00171 T* tmp = p->clone(); 00172 if (p->m_usecount.decAndTest()) 00173 { 00174 // only copy--don't need to clone, also not a race condition. 00175 // undo the decAndTest. 00176 p->m_usecount.inc(); 00177 delete tmp; // we won't need this anymore. 00178 return p; 00179 } 00180 else 00181 { 00182 // need to become unique 00183 if (tmp) 00184 COWIntrusiveReferenceAddRef(tmp); 00185 00186 return tmp; 00187 } 00188 } 00189 00190 } // end namespace BLOCXX_NAMESPACE 00191 00192 #endif 00193 00194