semaphore_posix.cpp

This software aims to create an applet and panel tools to manage a wireless interface card, such as

//
// Semaphore_POSIX.cpp
//
// $Id: //poco/Main/Foundation/src/Semaphore_POSIX.cpp#5 $
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#include "Foundation/Semaphore_POSIX.h"
#include <sys/time.h>


Foundation_BEGIN


SemaphoreImp::SemaphoreImp(int n, int max): _n(n), _max(max)
{
	poco_assert (n >= 0 && max > 0 && n <= max);

	if (pthread_mutex_init(&_mutex, NULL))
		throw SystemException("cannot create semaphore (mutex)");
	if (pthread_cond_init(&_cond, NULL))
		throw SystemException("cannot create semaphore (condition)");
}


SemaphoreImp::~SemaphoreImp()
{
	pthread_cond_destroy(&_cond);
	pthread_mutex_destroy(&_mutex);
}


void SemaphoreImp::waitImp()
{
	if (pthread_mutex_lock(&_mutex))
		throw SystemException("wait for semaphore failed (lock)"); 
	while (_n < 1) 
	{
		if (pthread_cond_wait(&_cond, &_mutex))
		{
			pthread_mutex_unlock(&_mutex);
			throw SystemException("wait for semaphore failed");
		}
	}
	--_n;
	pthread_mutex_unlock(&_mutex);
}


bool SemaphoreImp::waitImp(long milliseconds)
{
	int rc = 0;
	struct timespec abstime;

#if defined(__VMS)
	struct timespec delta;
	delta.tv_sec  = milliseconds / 1000;
	delta.tv_nsec = (milliseconds % 1000)*1000000;
	pthread_get_expiration_np(&delta, &abstime);
#else
	struct timeval tv;
	gettimeofday(&tv, NULL);
	abstime.tv_sec  = tv.tv_sec + milliseconds / 1000;
	abstime.tv_nsec = tv.tv_usec*1000 + (milliseconds % 1000)*1000000;
	if (abstime.tv_nsec >= 1000000000)
	{
		abstime.tv_nsec -= 1000000000;
		abstime.tv_sec++;
	}
#endif

	if (pthread_mutex_lock(&_mutex) != 0)
		throw SystemException("wait for semaphore failed (lock)"); 
	while (_n < 1) 
	{
		if ((rc = pthread_cond_timedwait(&_cond, &_mutex, &abstime)))
		{
			if (rc == ETIMEDOUT) break;
			pthread_mutex_unlock(&_mutex);
			throw SystemException("cannot wait for semaphore");
		}
	}
	if (rc == 0) --_n;
	pthread_mutex_unlock(&_mutex);
	return rc == 0;
}


Foundation_END