1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: $RCSfile: itkConditionVariable.h,v $
Language: C++
Date: $Date: 2007-01-26 14:28:44 $
Version: $Revision: 1.11 $
Copyright (c) Insight Software Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef __itkConditionVariable_h
#define __itkConditionVariable_h
#include "itkConfigure.h"
// This implementation uses a routine called SignalObjectAndWait()
// which is only defined on WinNT 4.0 or greater systems. We need to
// define this symbol in order to get the prototype for the
// routine. This needs to be done before we load any system headers.
#ifdef ITK_USE_WIN32_THREADS
#undef _WIN32_WINNT
#define _WIN32_WINNT 0x0400
#endif
#include "itkMutexLock.h"
#include "itkLightObject.h"
namespace itk {
/** \class ConditionVariable
* \brief A thread synchronization object used to suspend execution until some
* condition on shared data is met.
*
* A thread calls Wait() to suspend its execution until the condition is
* met. Each call to Signal() from an executing thread will then cause a single
* waiting thread to be released. A call to Signal() means, "signal
* that the condition is true." Broadcast() releases all threads waiting on
* the condition variable.
*
* The ITK ConditionVariable implementation is consistent with the standard
* definition and use of condition variables in pthreads and other common
* thread libraries.
*
* IMPORTANT: A condition variable always requires an associated SimpleMutexLock
* object. The mutex object is used to avoid a dangerous race condition when
* Wait() and Signal() are called simultaneously from two different
* threads.
*
* On systems using pthreads, this implementation abstract the
* standard calls to the pthread condition variable. On Win32
* systems, there is no system provided condition variable. This
* class implements a condition variable using a critical section, a
* semphore, an event and a number of counters. The implementation is
* almost an extract translation of the implementation presented by
* Douglas C Schmidt and Irfan Pyarali in "Strategies for Implementing
* POSIX Condition Variables on Win32". This article can be found at
* http://www.cs.wustl.edu/~schmidt/win32-cv-1.html
*
*/
class ITKCommon_EXPORT ConditionVariable : public LightObject
{
public:
/** Standard class typedefs. */
typedef ConditionVariable Self;
typedef LightObject Superclass;
typedef SmartPointer<Self> Pointer;
typedef SmartPointer<const Self> ConstPointer;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** Run-time type information (and related methods). */
itkTypeMacro(ConditionVariable, LightObject);
/** Suspend execution of this thread until the condition is signaled. The
* argument is a SimpleMutex object that must be locked prior to calling
* this method. */
void Wait(SimpleMutexLock * mutex);
/** Signal that the condition is true and release one waiting thread */
void Signal();
/** Signal that the condition is true and release all waiting threads */
void Broadcast();
protected:
ConditionVariable();
~ConditionVariable();
private:
ConditionVariable(const Self & other);
const Self & operator=( const Self & );
#ifdef ITK_USE_PTHREADS
pthread_cond_t m_ConditionVariable;
MutexType m_Mutex;
#else
int m_NumberOfWaiters; // number of waiting threads
#ifdef WIN32
CRITICAL_SECTION m_NumberOfWaitersLock; // Serialize access to
// m_NumberOfWaiters
HANDLE m_Semaphore; // Semaphore to queue threads
HANDLE m_WaitersAreDone; // Auto-reset event used by the
// broadcast/signal thread to
// wait for all the waiting
// threads to wake up and
// release the semaphore
size_t m_WasBroadcast; // Keeps track of whether we
// were broadcasting or signaling
#endif
#endif
};
} // end namespace itk
#endif
|
