pthreadcondition.c++

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/* -*-c++-*- OpenThreads library, Copyright (C) 2002 - 2007  The Open Thread Group
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/


//
// PThreadCondition.c++ - C++ Condition class built on top of posix threads.
// ~~~~~~~~~~~~~~~~~~~~
//

#if defined(_MSC_VER) || defined(__MINGW32__)
#  include <time.h>
#else
#  include <sys/time.h>
#endif

#include <stdio.h>

#include <OpenThreads/Condition>
#include "PThreadConditionPrivateData.h"
#include "PThreadMutexPrivateData.h"

using namespace OpenThreads;

#if defined(_MSC_VER) || defined(__MINGW32__)
int gettimeofday(struct timeval* tp, void* tzp) {
    LARGE_INTEGER t;

    if(QueryPerformanceCounter(&t)) {
	/* hardware supports a performance counter */
	static int been_here = 0;
	static LARGE_INTEGER f;
	if( !been_here )
	{
	    been_here = 1;
	    QueryPerformanceFrequency(&f);
	}
	tp->tv_sec = t.QuadPart/f.QuadPart;
	tp->tv_usec = ((float)t.QuadPart/f.QuadPart*1000*1000)
		      - (tp->tv_sec*1000*1000);
    } else {
	/* hardware doesn't support a performance counter, so get the
           time in a more traditional way. */
	DWORD t;
	t = timeGetTime();
	tp->tv_sec = t / 1000;
	tp->tv_usec = t % 1000;
    }

    /* 0 indicates that the call succeeded. */
    return 0;
}
#endif

//----------------------------------------------------------------------------
// This cancel cleanup handler is necessary to ensure that the barrier's
// mutex gets unlocked on cancel. Otherwise deadlocks could occur with 
// later joins.
//
void condition_cleanup_handler(void *arg) {

    pthread_mutex_t *mutex = static_cast<pthread_mutex_t *>(arg);
    
    pthread_mutex_unlock(mutex);

}

//----------------------------------------------------------------------------
//
// Decription: Constructor
//
// Use: public.
//
Condition::Condition() {

    PThreadConditionPrivateData *pd =
        new PThreadConditionPrivateData();

    int status = pthread_cond_init( &pd->condition, NULL );
    if (status)
    {
        printf("Error: pthread_cond_init(,) returned error status, status = %d\n",status);
    }

    _prvData = static_cast<void *>(pd);

}

//----------------------------------------------------------------------------
//
// Decription: Destructor
//
// Use: public.
//
Condition::~Condition() {

    PThreadConditionPrivateData *pd =
        static_cast<PThreadConditionPrivateData *>(_prvData);

    int status = pthread_cond_destroy( &pd->condition );
    if (status)
    {
        printf("Error: pthread_cond_destroy(,) returned error status, status = %d\n",status);
    }

    delete pd;

}

//----------------------------------------------------------------------------
//
// Decription: wait on a condition
//
// Use: public.
//
int Condition::wait(Mutex *mutex) {

    PThreadConditionPrivateData *pd =
        static_cast<PThreadConditionPrivateData *>(_prvData);

    PThreadMutexPrivateData *mpd =
        static_cast<PThreadMutexPrivateData *>(mutex->_prvData);

    int status;
    
    pthread_cleanup_push(condition_cleanup_handler, &mpd->mutex);

    status = pthread_cond_wait( &pd->condition, &mpd->mutex );

    pthread_cleanup_pop(0);

    return status;


}

//----------------------------------------------------------------------------
//
// Decription: wait on a condition, for a specified period of time
//
// Use: public.
//
int Condition::wait(Mutex *mutex, unsigned long int ms) {

    PThreadConditionPrivateData *pd =
        static_cast<PThreadConditionPrivateData *>(_prvData);

    PThreadMutexPrivateData *mpd =
        static_cast<PThreadMutexPrivateData *>(mutex->_prvData);


    // wait time is now in ms milliseconds, so need to convert to seconds and nanoseconds for timespec strucuture.
    unsigned int sec = ms / 1000;
    unsigned int nsec = (ms % 1000) * 1000000;

    // add to the current time    
    struct ::timeval now;
    ::gettimeofday( &now, 0 );

    sec += now.tv_sec;
    nsec += now.tv_usec*1000;

    // now pass on any overflow from nsec onto seconds.
    sec += nsec / 1000000000;
    nsec = nsec % 1000000000;

    struct timespec abstime;
    abstime.tv_sec = sec;
    abstime.tv_nsec = nsec;

    int status;

    pthread_cleanup_push(condition_cleanup_handler, &mpd->mutex);

    status = pthread_cond_timedwait( &pd->condition, &mpd->mutex, &abstime );

    pthread_cleanup_pop(0);

    return status;

}

//----------------------------------------------------------------------------
//
// Decription: signal a thread to wake up.
//
// Use: public.
//
int Condition::signal() {

    PThreadConditionPrivateData *pd =
        static_cast<PThreadConditionPrivateData *>(_prvData);

    return pthread_cond_signal( &pd->condition );
}

//----------------------------------------------------------------------------
//
// Decription: signal many threads to wake up.
//
// Use: public.
//
int Condition::broadcast() {

    PThreadConditionPrivateData *pd =
        static_cast<PThreadConditionPrivateData *>(_prvData);

    return pthread_cond_broadcast( &pd->condition );
}