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 #ifndef BLOCXX_COW_REFERENCE_BASE_HPP_INCLUDE_GUARD_ 00038 #define BLOCXX_COW_REFERENCE_BASE_HPP_INCLUDE_GUARD_ 00039 #include "blocxx/BLOCXX_config.h" 00040 #include "blocxx/RefCount.hpp" 00041 00042 // The classes and functions defined in this file are not meant for general 00043 // use, they are internal implementation details. They may change at any time. 00044 00045 namespace BLOCXX_NAMESPACE 00046 { 00047 00049 template<class T> 00050 inline void COWRefSwap(T& x, T&y) 00051 { 00052 T t = x; 00053 x = y; 00054 y = t; 00055 } 00056 00058 // This class contains the non-templated code for COWReference, to help 00059 // minimize code bloat. 00060 class BLOCXX_COMMON_API COWReferenceBase 00061 { 00062 protected: 00063 COWReferenceBase() 00064 : m_pRefCount(new RefCount) {} 00065 COWReferenceBase(const COWReferenceBase& arg) 00066 : m_pRefCount(arg.m_pRefCount) 00067 { 00068 m_pRefCount->inc(); 00069 } 00070 void incRef() 00071 { 00072 m_pRefCount->inc(); 00073 } 00074 00075 bool decRef() 00076 { 00077 if (m_pRefCount->decAndTest()) 00078 { 00079 delete m_pRefCount; 00080 return true; 00081 } 00082 return false; 00083 } 00084 00085 bool refCountGreaterThanOne() const 00086 { 00087 return m_pRefCount->get() > 1; 00088 } 00089 00090 // returns true if we're the only copy. 00091 bool getWriteLock() 00092 { 00093 if (m_pRefCount->decAndTest()) 00094 { 00095 // only copy--don't need to clone, also not a race condition 00096 incRef(); 00097 return true; 00098 } 00099 else 00100 { 00101 // need to become unique 00102 m_pRefCount = new RefCount; 00103 return false; 00104 } 00105 } 00106 00107 void swap(COWReferenceBase& arg) 00108 { 00109 COWRefSwap(m_pRefCount, arg.m_pRefCount); 00110 } 00111 00112 #ifdef BLOCXX_CHECK_NULL_REFERENCES 00113 static void throwNULLException(); 00114 static void checkNull(const void* p) 00115 { 00116 if (p == 0) 00117 { 00118 throwNULLException(); 00119 } 00120 } 00121 #endif 00122 00123 void useRefCountOf(const COWReferenceBase& arg) 00124 { 00125 decRef(); 00126 m_pRefCount = arg.m_pRefCount; 00127 incRef(); 00128 } 00129 00130 protected: 00131 RefCount* volatile m_pRefCount; 00132 }; 00133 00134 } // end namespace BLOCXX_NAMESPACE 00135 00136 #endif 00137 00138