OpenWalnut  1.3.1
WSharedObjectTicketRead.h
1 //---------------------------------------------------------------------------
2 //
3 // Project: OpenWalnut ( http://www.openwalnut.org )
4 //
5 // Copyright 2009 OpenWalnut Community, BSV@Uni-Leipzig and CNCF@MPI-CBS
6 // For more information see http://www.openwalnut.org/copying
7 //
8 // This file is part of OpenWalnut.
9 //
10 // OpenWalnut is free software: you can redistribute it and/or modify
11 // it under the terms of the GNU Lesser General Public License as published by
12 // the Free Software Foundation, either version 3 of the License, or
13 // (at your option) any later version.
14 //
15 // OpenWalnut is distributed in the hope that it will be useful,
16 // but WITHOUT ANY WARRANTY; without even the implied warranty of
17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 // GNU Lesser General Public License for more details.
19 //
20 // You should have received a copy of the GNU Lesser General Public License
21 // along with OpenWalnut. If not, see <http://www.gnu.org/licenses/>.
22 //
23 //---------------------------------------------------------------------------
24 
25 #ifndef WSHAREDOBJECTTICKETREAD_H
26 #define WSHAREDOBJECTTICKETREAD_H
27 
28 #include <boost/shared_ptr.hpp>
29 
30 #include "WCondition.h"
31 #include "WSharedObjectTicket.h"
32 
33 /**
34  * 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
35  * has been destroyed. This class especially implements the shared (read) lock.
36  */
37 template < typename Data >
39 {
40 // the shared object class needs protected access to create new instances
41 friend class WSharedObject< Data >;
42 public:
43  /**
44  * Destroys the ticket and releases the lock.
45  */
47  {
48  // explicitly unlock to ensure the WSharedObjectTicket destructor can call the update callback AFTER the lock has been released
49  unlock();
50  };
51 
52  /**
53  * Returns the protected data. As long as you own the ticket, you are allowed to use it.
54  *
55  * \note making it const enforces const correctness for contained types!
56  *
57  * \return the data (const!)
58  */
59  const Data& get() const
60  {
62  };
63 
64 protected:
65  /**
66  * Create a new instance. It is protected to avoid someone to create them. It locks the mutex for read.
67  *
68  * \param data the data to protect
69  * \param mutex the mutex used to lock
70  * \param condition a condition that should be fired upon unlock. Can be NULL.
71  */
72  WSharedObjectTicketRead( Data& data, boost::shared_ptr< boost::shared_mutex > mutex, boost::shared_ptr< WCondition > condition ): // NOLINT
73  WSharedObjectTicket< Data >( data, mutex, condition ),
74  m_lock( boost::shared_lock< boost::shared_mutex >( *mutex ) )
75  {
76  };
77 
78  /**
79  * The lock.
80  */
81  boost::shared_lock< boost::shared_mutex > m_lock;
82 
83  /**
84  * Unlocks the mutex.
85  */
86  virtual void unlock()
87  {
88  m_lock.unlock();
89  }
90 
91 private:
92 };
93 
94 #endif // WSHAREDOBJECTTICKETREAD_H
95