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 #ifndef BLOCXX_CBLOCXX_REFERENCE_BASE_HPP_INCLUDE_GUARD_ 00039 #define BLOCXX_CBLOCXX_REFERENCE_BASE_HPP_INCLUDE_GUARD_ 00040 #include "blocxx/BLOCXX_config.h" 00041 #include "blocxx/RefCount.hpp" 00042 00043 // The classes and functions defined in this file are not meant for general 00044 // use, they are internal implementation details. They may change at any time. 00045 00046 namespace BLOCXX_NAMESPACE 00047 { 00048 00050 template<class T> 00051 inline void COWRefSwap(T& x, T&y) 00052 { 00053 T t = x; 00054 x = y; 00055 y = t; 00056 } 00057 00059 // This class contains the non-templated code for COWReference, to help 00060 // minimize code bloat. 00061 class BLOCXX_COMMON_API COWReferenceBase 00062 { 00063 protected: 00064 COWReferenceBase() 00065 : m_pRefCount(new RefCount) {} 00066 COWReferenceBase(const COWReferenceBase& arg) 00067 : m_pRefCount(arg.m_pRefCount) 00068 { 00069 m_pRefCount->inc(); 00070 } 00071 void incRef() 00072 { 00073 m_pRefCount->inc(); 00074 } 00075 00076 bool decRef() 00077 { 00078 if (m_pRefCount->decAndTest()) 00079 { 00080 delete m_pRefCount; 00081 return true; 00082 } 00083 return false; 00084 } 00085 00086 bool refCountGreaterThanOne() const 00087 { 00088 return m_pRefCount->get() > 1; 00089 } 00090 00091 // returns true if we're the only copy. 00092 bool getWriteLock() 00093 { 00094 if (m_pRefCount->decAndTest()) 00095 { 00096 // only copy--don't need to clone, also not a race condition 00097 incRef(); 00098 return true; 00099 } 00100 else 00101 { 00102 // need to become unique 00103 m_pRefCount = new RefCount; 00104 return false; 00105 } 00106 } 00107 00108 void swap(COWReferenceBase& arg) 00109 { 00110 COWRefSwap(m_pRefCount, arg.m_pRefCount); 00111 } 00112 00113 void useRefCountOf(const COWReferenceBase& arg) 00114 { 00115 decRef(); 00116 m_pRefCount = arg.m_pRefCount; 00117 incRef(); 00118 } 00119 00120 protected: 00121 RefCount* volatile m_pRefCount; 00122 }; 00123 00124 } // end namespace BLOCXX_NAMESPACE 00125 00126 #endif 00127 00128