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 WSHAREDOBJECTTICKETREAD_H 00026 #define WSHAREDOBJECTTICKETREAD_H 00027 00028 #include <boost/shared_ptr.hpp> 00029 00030 #include "WCondition.h" 00031 #include "WSharedObjectTicket.h" 00032 00033 /** 00034 * 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 00035 * has been destroyed. This class especially implements the shared (read) lock. 00036 */ 00037 template < typename Data > 00038 class WSharedObjectTicketRead: public WSharedObjectTicket< Data > 00039 { 00040 // the shared object class needs protected access to create new instances 00041 friend class WSharedObject< Data >; 00042 public: 00043 /** 00044 * Destroys the ticket and releases the lock. 00045 */ 00046 virtual ~WSharedObjectTicketRead() 00047 { 00048 // explicitly unlock to ensure the WSharedObjectTicket destructor can call the update callback AFTER the lock has been released 00049 unlock(); 00050 }; 00051 00052 /** 00053 * Returns the protected data. As long as you own the ticket, you are allowed to use it. 00054 * 00055 * \note making it const enforces const correctness for contained types! 00056 * 00057 * \return the data (const!) 00058 */ 00059 const Data& get() const 00060 { 00061 return WSharedObjectTicket< Data >::m_data; 00062 }; 00063 00064 protected: 00065 /** 00066 * Create a new instance. It is protected to avoid someone to create them. It locks the mutex for read. 00067 * 00068 * \param data the data to protect 00069 * \param mutex the mutex used to lock 00070 * \param condition a condition that should be fired upon unlock. Can be NULL. 00071 */ 00072 WSharedObjectTicketRead( Data& data, boost::shared_ptr< boost::shared_mutex > mutex, boost::shared_ptr< WCondition > condition ): // NOLINT 00073 WSharedObjectTicket< Data >( data, mutex, condition ), 00074 m_lock( boost::shared_lock< boost::shared_mutex >( *mutex ) ) 00075 { 00076 }; 00077 00078 /** 00079 * The lock. 00080 */ 00081 boost::shared_lock< boost::shared_mutex > m_lock; 00082 00083 /** 00084 * Unlocks the mutex. 00085 */ 00086 virtual void unlock() 00087 { 00088 m_lock.unlock(); 00089 } 00090 00091 private: 00092 }; 00093 00094 #endif // WSHAREDOBJECTTICKETREAD_H 00095