1 /* 2 * Copyright (C) 2008 Tommi Maekitalo 3 * 4 * This library is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Lesser General Public 6 * License as published by the Free Software Foundation; either 7 * version 2.1 of the License, or (at your option) any later version. 8 * 9 * As a special exception, you may use this file as part of a free 10 * software library without restriction. Specifically, if other files 11 * instantiate templates or use macros or inline functions from this 12 * file, or you compile this file and link it with other files to 13 * produce an executable, this file does not by itself cause the 14 * resulting executable to be covered by the GNU General Public 15 * License. This exception does not however invalidate any other 16 * reasons why the executable file might be covered by the GNU Library 17 * General Public License. 18 * 19 * This library is distributed in the hope that it will be useful, 20 * but WITHOUT ANY WARRANTY; without even the implied warranty of 21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22 * Lesser General Public License for more details. 23 * 24 * You should have received a copy of the GNU Lesser General Public 25 * License along with this library; if not, write to the Free Software 26 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 27 */ 28 29 #include <cxxtools/mutex.h> 30 #include <cxxtools/condition.h> 31 #include <cxxtools/clock.h> 32 #include <stdint.h> 33 34 template <typename T> 35 class ModificationTracker 36 { 37 T _value; 38 unsigned _serial; 39 mutable cxxtools::Mutex _mutex; 40 mutable cxxtools::Condition _condition; 41 42 public: 43 typedef std::pair<T, unsigned> ValueSerial; 44 ModificationTracker()45 ModificationTracker() 46 : _serial(0) 47 { } 48 49 /// set value set(const T & value)50 void set(const T& value) 51 { 52 cxxtools::MutexLock lock(_mutex); 53 _value = value; 54 ++_serial; 55 _condition.broadcast(); 56 } 57 58 /// get value and serial number of value get()59 ValueSerial get() const 60 { 61 cxxtools::MutexLock lock(_mutex); 62 return ValueSerial(_value, _serial); 63 } 64 65 /// wait value change up to specified timeout get(unsigned serial,unsigned timeoutMsec)66 ValueSerial get(unsigned serial, unsigned timeoutMsec) const 67 { 68 cxxtools::MutexLock lock(_mutex); 69 cxxtools::Clock clock; 70 clock.start(); 71 while (_serial <= serial) 72 { 73 int64_t timeoutLeft = static_cast<int64_t>(timeoutMsec) - clock.stop().totalMSecs(); 74 if (timeoutLeft <= 0) 75 break; 76 77 _condition.wait(lock, timeoutLeft); 78 } 79 80 return ValueSerial(_value, _serial); 81 } 82 83 }; 84