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WSharedObjectTicketRead.h
1 //---------------------------------------------------------------------------
2 //
3 // Project: OpenWalnut ( http://www.openwalnut.org )
4 //
5 // Copyright 2009 OpenWalnut Community, BSV@Uni-Leipzig and CNCF@MPI-CBS
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8 // This file is part of OpenWalnut.
9 //
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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  /**
45  * Destroys the ticket and releases the lock.
46  */
48  {
49  // explicitly unlock to ensure the WSharedObjectTicket destructor can call the update callback AFTER the lock has been released
50  unlock();
51  };
52 
53  /**
54  * Returns the protected data. As long as you own the ticket, you are allowed to use it.
55  *
56  * \note making it const enforces const correctness for contained types!
57  *
58  * \return the data (const!)
59  */
60  const Data& get() const
61  {
63  };
64 
65 protected:
66 
67  /**
68  * Create a new instance. It is protected to avoid someone to create them. It locks the mutex for read.
69  *
70  * \param data the data to protect
71  * \param mutex the mutex used to lock
72  * \param condition a condition that should be fired upon unlock. Can be NULL.
73  */
74  WSharedObjectTicketRead( Data& data, boost::shared_ptr< boost::shared_mutex > mutex, boost::shared_ptr< WCondition > condition ): // NOLINT
75  WSharedObjectTicket< Data >( data, mutex, condition ),
76  m_lock( boost::shared_lock< boost::shared_mutex >( *mutex ) )
77  {
78  };
79 
80  /**
81  * The lock.
82  */
83  boost::shared_lock< boost::shared_mutex > m_lock;
84 
85  /**
86  * Unlocks the mutex.
87  */
88  virtual void unlock()
89  {
90  m_lock.unlock();
91  }
92 
93 private:
94 };
95 
96 #endif // WSHAREDOBJECTTICKETREAD_H
97