00001 /******************************************************************************* 00002 * Copyright (C) 2004 Vintela, Inc. All rights reserved. 00003 * Copyright (C) 2005 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 * 00011 * - Redistributions in binary form must reproduce the above copyright notice, 00012 * this list of conditions and the following disclaimer in the documentation 00013 * and/or other materials provided with the distribution. 00014 * 00015 * - Neither the name of Vintela, Inc., Novell, Inc., nor the names of its 00016 * contributors may be used to endorse or promote products derived from this 00017 * software without specific prior written permission. 00018 * 00019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' 00020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 00021 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 00022 * ARE DISCLAIMED. IN NO EVENT SHALL Vintela, Inc., Novell, Inc., OR THE 00023 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 00024 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 00025 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 00026 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 00027 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 00028 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 00029 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00030 *******************************************************************************/ 00031 00032 00037 // 00038 // Copyright (c) 2001, 2002 Peter Dimov 00039 // 00040 // Permission to copy, use, modify, sell and distribute this software 00041 // is granted provided this copyright notice appears in all copies. 00042 // This software is provided "as is" without express or implied 00043 // warranty, and with no claim as to its suitability for any purpose. 00044 // 00045 00046 #ifndef BLOCXX_COW_INTRUSIVE_COUNTABLE_BASE_HPP_INCLUDE_GUARD_ 00047 #define BLOCXX_COW_INTRUSIVE_COUNTABLE_BASE_HPP_INCLUDE_GUARD_ 00048 00049 #include "blocxx/BLOCXX_config.h" 00050 #include "blocxx/RefCount.hpp" 00051 00052 namespace BLOCXX_NAMESPACE 00053 { 00054 00071 class COWIntrusiveCountableBase; 00072 void COWIntrusiveReferenceAddRef(COWIntrusiveCountableBase * p); 00073 void COWIntrusiveReferenceRelease(COWIntrusiveCountableBase * p); 00074 bool COWIntrusiveReferenceUnique(COWIntrusiveCountableBase* p); 00075 template <typename T> T* COWIntrusiveReferenceClone(T* p); 00076 00077 class BLOCXX_COMMON_API COWIntrusiveCountableBase 00078 { 00079 private: 00080 RefCount m_usecount; 00081 00082 protected: 00086 COWIntrusiveCountableBase(COWIntrusiveCountableBase const &) 00087 : m_usecount(0) 00088 { 00089 } 00090 00094 COWIntrusiveCountableBase(): m_usecount(0) 00095 { 00096 } 00097 00103 COWIntrusiveCountableBase& operator=(COWIntrusiveCountableBase const &x) 00104 { 00105 // don't assign or change the ref count, since it won't be different. 00106 return *this; 00107 } 00108 00112 virtual ~COWIntrusiveCountableBase(); 00113 00117 RefCount getRefCount() const 00118 { 00119 return m_usecount; 00120 } 00121 00122 public: 00123 00129 inline friend void COWIntrusiveReferenceAddRef(COWIntrusiveCountableBase * p) 00130 { 00131 p->m_usecount.inc(); 00132 } 00133 00141 inline friend void COWIntrusiveReferenceRelease(COWIntrusiveCountableBase * p) 00142 { 00143 if (p->m_usecount.decAndTest()) 00144 delete p; 00145 } 00146 00153 inline friend bool COWIntrusiveReferenceUnique(COWIntrusiveCountableBase* p) 00154 { 00155 return p->m_usecount.get() == 1; 00156 } 00157 00164 template <typename T> 00165 friend T* COWIntrusiveReferenceClone(T* p); 00166 }; 00167 00168 template <typename T> 00169 inline T* COWIntrusiveReferenceClone(T* p) 00170 { 00171 // this needs to happen first to avoid a race condition between 00172 // another thread deleting the object and this one making a copy. 00173 T* tmp = p->clone(); 00174 if (p->m_usecount.decAndTest()) 00175 { 00176 // only copy--don't need to clone, also not a race condition. 00177 // undo the decAndTest. 00178 p->m_usecount.inc(); 00179 delete tmp; // we won't need this anymore. 00180 return p; 00181 } 00182 else 00183 { 00184 // need to become unique 00185 if (tmp) 00186 COWIntrusiveReferenceAddRef(tmp); 00187 return tmp; 00188 } 00189 } 00190 00191 } // end namespace BLOCXX_NAMESPACE 00192 00193 #endif 00194 00195