BufferLockFree.hpp
Go to the documentation of this file.00001 /*************************************************************************** 00002 tag: Peter Soetens Thu Jan 13 10:24:51 CET 2005 BufferLockFree.hpp 00003 00004 BufferLockFree.hpp - description 00005 ------------------- 00006 begin : Thu January 13 2005 00007 copyright : (C) 2005 Peter Soetens 00008 email : peter.soetens@mech.kuleuven.ac.be 00009 00010 *************************************************************************** 00011 * This library is free software; you can redistribute it and/or * 00012 * modify it under the terms of the GNU General Public * 00013 * License as published by the Free Software Foundation; * 00014 * version 2 of the License. * 00015 * * 00016 * As a special exception, you may use this file as part of a free * 00017 * software library without restriction. Specifically, if other files * 00018 * instantiate templates or use macros or inline functions from this * 00019 * file, or you compile this file and link it with other files to * 00020 * produce an executable, this file does not by itself cause the * 00021 * resulting executable to be covered by the GNU General Public * 00022 * License. This exception does not however invalidate any other * 00023 * reasons why the executable file might be covered by the GNU General * 00024 * Public License. * 00025 * * 00026 * This library is distributed in the hope that it will be useful, * 00027 * but WITHOUT ANY WARRANTY; without even the implied warranty of * 00028 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * 00029 * Lesser General Public License for more details. * 00030 * * 00031 * You should have received a copy of the GNU General Public * 00032 * License along with this library; if not, write to the Free Software * 00033 * Foundation, Inc., 59 Temple Place, * 00034 * Suite 330, Boston, MA 02111-1307 USA * 00035 * * 00036 ***************************************************************************/ 00037 00038 #ifndef ORO_BUFFER_LOCK_FREE_HPP 00039 #define ORO_BUFFER_LOCK_FREE_HPP 00040 00041 #include "../os/oro_arch.h" 00042 #include "../os/CAS.hpp" 00043 #include "BufferInterface.hpp" 00044 #include "../internal/AtomicMWSRQueue.hpp" 00045 #include "../internal/TsPool.hpp" 00046 #include <vector> 00047 00048 #ifdef ORO_PRAGMA_INTERFACE 00049 #pragma interface 00050 #endif 00051 00052 namespace RTT 00053 { namespace base { 00054 00055 00056 using os::CAS; 00057 00067 template< class T> 00068 class BufferLockFree 00069 : public BufferInterface<T> 00070 { 00071 public: 00072 typedef typename BufferInterface<T>::reference_t reference_t; 00073 typedef typename BufferInterface<T>::param_t param_t; 00074 typedef typename BufferInterface<T>::size_type size_type; 00075 typedef T value_t; 00076 private: 00077 typedef T Item; 00078 internal::AtomicMWSRQueue<Item*> bufs; 00079 // is mutable because of reference counting. 00080 mutable internal::TsPool<Item> mpool; 00081 const bool mcircular; 00082 public: 00087 BufferLockFree( unsigned int bufsize, const T& initial_value = T(), bool circular = false) 00088 : bufs( bufsize ), mpool(bufsize + 1), mcircular(circular) 00089 { 00090 mpool.data_sample( initial_value ); 00091 } 00092 00093 ~BufferLockFree() { 00094 // free all items still in the buffer. 00095 clear(); 00096 } 00097 00098 virtual void data_sample( const T& sample ) 00099 { 00100 mpool.data_sample(sample); 00101 } 00102 00103 virtual T data_sample() const 00104 { 00105 T result = T(); 00106 Item* mitem = mpool.allocate(); 00107 if (mitem != 0) { 00108 result = *mitem; 00109 mpool.deallocate( mitem ); 00110 } 00111 return result; 00112 } 00113 00114 00115 size_type capacity() const 00116 { 00117 return bufs.capacity(); 00118 } 00119 00120 size_type size() const 00121 { 00122 return bufs.size(); 00123 } 00124 00125 bool empty() const 00126 { 00127 return bufs.isEmpty(); 00128 } 00129 00130 bool full() const 00131 { 00132 return bufs.isFull(); 00133 } 00134 00135 void clear() 00136 { 00137 Item* item; 00138 while ( bufs.dequeue(item) ) 00139 mpool.deallocate( item ); 00140 } 00141 00142 bool Push( param_t item) 00143 { 00144 if ( capacity() == (size_type)bufs.size() ) { 00145 if (!mcircular) 00146 return false; 00147 // we will recover below in case of circular 00148 } 00149 Item* mitem = mpool.allocate(); 00150 if ( mitem == 0 ) { // queue full ( rare but possible in race with PopWithoutRelease ) 00151 if (!mcircular) 00152 return false; 00153 else { 00154 if (bufs.dequeue( mitem ) == false ) 00155 return false; // assert(false) ??? 00156 // we keep mitem to write item to next 00157 } 00158 } 00159 00160 // copy over. 00161 *mitem = item; 00162 if (bufs.enqueue( mitem ) == false ) { 00163 //got memory, but buffer is full 00164 //this can happen, as the memory pool is 00165 //bigger than the buffer 00166 if (!mcircular) { 00167 mpool.deallocate( mitem ); 00168 return false; 00169 } else { 00170 // pop & deallocate until we have free space. 00171 Item* itmp = 0; 00172 do { 00173 bufs.dequeue( itmp ); 00174 mpool.deallocate( itmp ); 00175 } while ( bufs.enqueue( mitem ) == false ); 00176 } 00177 } 00178 return true; 00179 } 00180 00181 size_type Push(const std::vector<T>& items) 00182 { 00183 // @todo Make this function more efficient as in BufferLocked. 00184 int towrite = items.size(); 00185 typename std::vector<T>::const_iterator it; 00186 for( it = items.begin(); it != items.end(); ++it) 00187 if ( this->Push( *it ) == false ) { 00188 break; // will only happen in non-circular case ! 00189 } 00190 return towrite - (items.end() - it); 00191 } 00192 00193 00194 bool Pop( reference_t item ) 00195 { 00196 Item* ipop; 00197 if (bufs.dequeue( ipop ) == false ) 00198 return false; 00199 item = *ipop; 00200 if (mpool.deallocate( ipop ) == false ) 00201 assert(false); 00202 return true; 00203 } 00204 00205 size_type Pop(std::vector<T>& items ) 00206 { 00207 Item* ipop; 00208 items.clear(); 00209 while( bufs.dequeue(ipop) ) { 00210 items.push_back( *ipop ); 00211 if (mpool.deallocate(ipop) == false) 00212 assert(false); 00213 } 00214 return items.size(); 00215 } 00216 00217 value_t* PopWithoutRelease() 00218 { 00219 Item* ipop; 00220 if (bufs.dequeue( ipop ) == false ) 00221 return 0; 00222 return ipop; 00223 } 00224 00225 void Release(value_t *item) 00226 { 00227 if (mpool.deallocate( item ) == false ) 00228 assert(false); 00229 } 00230 }; 00231 }} 00232 00233 #endif