/src/FreeImage/Source/OpenEXR/IlmThread/IlmThreadMutex.h

  1///////////////////////////////////////////////////////////////////////////
  2//
  3// Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
  4// Digital Ltd. LLC
  5// 
  6// All rights reserved.
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 33///////////////////////////////////////////////////////////////////////////
 34
 35#ifndef INCLUDED_ILM_THREAD_MUTEX_H
 36#define INCLUDED_ILM_THREAD_MUTEX_H
 37
 38//-----------------------------------------------------------------------------
 39//
 40//	class Mutex, class Lock
 41//
 42//	Class Mutex is a wrapper for a system-dependent mutual exclusion
 43//	mechanism.  Actual locking and unlocking of a Mutex object must
 44//	be performed using an instance of a Lock (defined below).
 45//
 46//	Class lock provides safe locking and unlocking of mutexes even in
 47//	the presence of C++ exceptions.  Constructing a Lock object locks
 48//	the mutex; destroying the Lock unlocks the mutex.
 49//
 50//	Lock objects are not themselves thread-safe.  You should never
 51//	share a Lock object among multiple threads.
 52//
 53//	Typical usage:
 54//    
 55//	    Mutex mtx;	// Create a Mutex object that is visible
 56//	    		//to multiple threads
 57//
 58//	    ...		// create some threads
 59//
 60//	    // Then, within each thread, construct a critical section like so:
 61//
 62//	    {
 63//		Lock lock (mtx);	// Lock constructor locks the mutex
 64//		...			// do some computation on shared data
 65//	    }				// leaving the block unlocks the mutex
 66//
 67//-----------------------------------------------------------------------------
 68
 69#include "IlmBaseConfig.h"
 70
 71#if defined _WIN32 || defined _WIN64
 72    #ifdef NOMINMAX
 73        #undef NOMINMAX
 74    #endif
 75    #define NOMINMAX
 76    #include <windows.h>
 77#elif HAVE_PTHREAD
 78    #include <pthread.h>
 79#endif
 80
 81namespace IlmThread {
 82
 83class Lock;
 84
 85
 86class Mutex
 87{
 88  public:
 89
 90    Mutex ();
 91    virtual ~Mutex ();
 92
 93  private:
 94
 95    void	lock () const;
 96    void	unlock () const;
 97
 98    #if defined _WIN32 || defined _WIN64
 99	mutable CRITICAL_SECTION _mutex;
100    #elif HAVE_PTHREAD
101	mutable pthread_mutex_t _mutex;
102    #endif
103
104    void operator = (const Mutex& M);	// not implemented
105    Mutex (const Mutex& M);		// not implemented
106    
107    friend class Lock;
108};
109
110
111class Lock
112{
113  public:
114
115    Lock (const Mutex& m, bool autoLock = true):
116	_mutex (m),
117	_locked (false)
118    {
119        if (autoLock)
120        {
121            _mutex.lock();
122            _locked = true;
123        }
124    }
125    
126    ~Lock ()
127    {
128        if (_locked)
129            _mutex.unlock();
130    }
131    
132    void acquire ()
133    {
134        _mutex.lock();
135        _locked = true;
136    }
137    
138    void release ()
139    {
140        _mutex.unlock();
141        _locked = false;
142    }
143    
144    bool locked ()
145    {
146        return _locked;
147    }
148
149  private:
150
151    const Mutex &	_mutex;
152    bool		_locked;
153};
154
155
156} // namespace IlmThread
157
158#endif