OpenWalnut
1.4.0
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00001 //--------------------------------------------------------------------------- 00002 // 00003 // Project: OpenWalnut ( http://www.openwalnut.org ) 00004 // 00005 // Copyright 2009 OpenWalnut Community, BSV@Uni-Leipzig and CNCF@MPI-CBS 00006 // For more information see http://www.openwalnut.org/copying 00007 // 00008 // This file is part of OpenWalnut. 00009 // 00010 // OpenWalnut is free software: you can redistribute it and/or modify 00011 // it under the terms of the GNU Lesser General Public License as published by 00012 // the Free Software Foundation, either version 3 of the License, or 00013 // (at your option) any later version. 00014 // 00015 // OpenWalnut is distributed in the hope that it will be useful, 00016 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00018 // GNU Lesser General Public License for more details. 00019 // 00020 // You should have received a copy of the GNU Lesser General Public License 00021 // along with OpenWalnut. If not, see <http://www.gnu.org/licenses/>. 00022 // 00023 //--------------------------------------------------------------------------- 00024 00025 #ifndef WSHAREDOBJECTTICKET_H 00026 #define WSHAREDOBJECTTICKET_H 00027 00028 #include <boost/shared_ptr.hpp> 00029 00030 #include "WCondition.h" 00031 00032 // The shared object class 00033 template < typename T > 00034 class WSharedObject; 00035 00036 /** 00037 * Class which represents granted access to a locked object. It contains a reference to the object and a lock. The lock is freed after the ticket 00038 * has been destroyed. 00039 * 00040 * \note This class does not provide any member to actually get the contained value/instance. This is done in read and write tickets. 00041 */ 00042 template < typename Data > 00043 class WSharedObjectTicket 00044 { 00045 // the shared object class needs protected access to create new instances 00046 friend class WSharedObject< Data >; 00047 public: 00048 /** 00049 * Destroys the ticket and releases the lock. 00050 */ 00051 virtual ~WSharedObjectTicket() 00052 { 00053 // NOTE: the derived destructor already unlocks. 00054 if( m_condition ) 00055 { 00056 m_condition->notify(); 00057 } 00058 }; 00059 00060 /** 00061 * If called, the unlock will NOT fire the condition. This is useful in some situations if you find out "hey there actually was nothing 00062 * changed". 00063 */ 00064 void suppressUnlockCondition() 00065 { 00066 m_condition = boost::shared_ptr< WCondition >(); 00067 } 00068 00069 protected: 00070 /** 00071 * Create a new instance. It is protected to avoid someone to create them. It locks the mutex. 00072 * 00073 * \param data the data to protect 00074 * \param mutex the mutex used to lock 00075 * \param condition a condition that should be fired upon unlock. Can be NULL. 00076 */ 00077 WSharedObjectTicket( Data& data, boost::shared_ptr< boost::shared_mutex > mutex, boost::shared_ptr< WCondition > condition ): // NOLINT 00078 m_data( data ), 00079 m_mutex( mutex ), 00080 m_condition( condition ) 00081 { 00082 }; 00083 00084 /** 00085 * The data to which access is allowed by the ticket 00086 */ 00087 Data& m_data; 00088 00089 /** 00090 * The mutex used for locking. 00091 */ 00092 boost::shared_ptr< boost::shared_mutex > m_mutex; 00093 00094 /** 00095 * A condition which gets notified after unlocking. Especially useful to notify waiting threads about a change in the object. 00096 */ 00097 boost::shared_ptr< WCondition > m_condition; 00098 00099 /** 00100 * Unlocks the mutex. 00101 */ 00102 virtual void unlock() = 0; 00103 00104 private: 00105 }; 00106 00107 #endif // WSHAREDOBJECTTICKET_H 00108