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WSharedObject.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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22 //
23 //---------------------------------------------------------------------------
24 
25 #ifndef WSHAREDOBJECT_H
26 #define WSHAREDOBJECT_H
27 
28 #include <boost/thread.hpp>
29 
30 #include "WCondition.h"
31 #include "WSharedObjectTicket.h"
32 #include "WSharedObjectTicketRead.h"
33 #include "WSharedObjectTicketWrite.h"
34 
35 /**
36  * Wrapper around an object/type for thread safe sharing of objects among multiple threads. The advantage of this class over WFlag
37  * is, that WFlag just protects simple get/set operations, while this class can protect a whole bunch of operations on the
38  * encapsulated object.
39  */
40 template < typename T >
42 {
43 public:
44 
45  /**
46  * Default constructor.
47  */
48  WSharedObject();
49 
50  /**
51  * Destructor.
52  */
53  virtual ~WSharedObject();
54 
55  /**
56  * Type for read tickets.
57  */
58  typedef boost::shared_ptr< WSharedObjectTicketRead< T > > ReadTicket;
59 
60  /**
61  * Type for write tickets.
62  */
63  typedef boost::shared_ptr< WSharedObjectTicketWrite< T > > WriteTicket;
64 
65  /**
66  * Returns a ticket to get read access to the contained data. After the ticket is freed, the read lock vanishes.
67  *
68  * \return the read ticket
69  */
70  ReadTicket getReadTicket() const;
71 
72  /**
73  * Returns a ticket to get write access to the contained data. After the ticket is freed, the write lock vanishes.
74  *
75  * \param suppressNotify true if no notification should be send after unlocking.
76  *
77  * \return the ticket
78  */
79  WriteTicket getWriteTicket( bool suppressNotify = false ) const;
80 
81  /**
82  * This condition fires whenever the encapsulated object changed. This is fired automatically by endWrite().
83  *
84  * \return the condition
85  */
86  boost::shared_ptr< WCondition > getChangeCondition() const;
87 
88 protected:
89 
90  /**
91  * The object wrapped by this class. This member is mutable as the \ref getReadTicket and \ref getWriteTicket functions are const but need a
92  * non-const reference to m_object.
93  */
94  mutable T m_object;
95 
96  /**
97  * The lock to ensure thread safe access. This member is mutable as the \ref getReadTicket and \ref getWriteTicket functions are const but need a
98  * non-const reference to m_lock.
99  */
100  mutable boost::shared_ptr< boost::shared_mutex > m_lock;
101 
102  /**
103  * This condition set fires whenever the contained object changes. This corresponds to the Observable pattern.
104  */
105  boost::shared_ptr< WCondition > m_changeCondition;
106 
107 private:
108 };
109 
110 template < typename T >
112  m_lock( new boost::shared_mutex ),
113  m_changeCondition( new WCondition() )
114 {
115  // init members
116 }
117 
118 template < typename T >
120 {
121  // clean up
122 }
123 
124 template < typename T >
125 boost::shared_ptr< WCondition > WSharedObject< T >::getChangeCondition() const
126 {
127  return m_changeCondition;
128 }
129 
130 template < typename T >
132 {
133  return boost::shared_ptr< WSharedObjectTicketRead< T > >(
134  new WSharedObjectTicketRead< T >( m_object, m_lock, boost::shared_ptr< WCondition >() )
135  );
136 }
137 
138 template < typename T >
140 {
141  if( suppressNotify )
142  {
143  return boost::shared_ptr< WSharedObjectTicketWrite< T > >(
144  new WSharedObjectTicketWrite< T >( m_object, m_lock, boost::shared_ptr< WCondition >() )
145  );
146  }
147  else
148  {
149  return boost::shared_ptr< WSharedObjectTicketWrite< T > >(
150  new WSharedObjectTicketWrite< T >( m_object, m_lock, m_changeCondition )
151  );
152  }
153 }
154 
155 #endif // WSHAREDOBJECT_H
156