poco/Foundation/src/Semaphore_POSIX.cpp

//
// Semaphore_POSIX.cpp
//
// $Id: //poco/1.4/Foundation/src/Semaphore_POSIX.cpp#3 $
//
// Library: Foundation
// Package: Threading
// Module:  Semaphore
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#include "Poco/Semaphore_POSIX.h"
#if defined(POCO_VXWORKS)
#include <timers.h>
#include <cstring>
#else
#include <sys/time.h>
#endif


namespace Poco {


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

#if defined(POCO_VXWORKS)
	// This workaround is for VxWorks 5.x where
	// pthread_mutex_init() won't properly initialize the mutex
	// resulting in a subsequent freeze in pthread_mutex_destroy()
	// if the mutex has never been used.
	std::memset(&_mutex, 0, sizeof(_mutex));
#endif
	if (pthread_mutex_init(&_mutex, NULL))
		throw SystemException("cannot create semaphore (mutex)");
	if (pthread_cond_init(&_cond, NULL))
		throw SystemException("cannot create semaphore (condition)");
}


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


void SemaphoreImpl::waitImpl()
{
	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 SemaphoreImpl::waitImpl(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);
#elif defined(POCO_VXWORKS)
	clock_gettime(CLOCK_REALTIME, &abstime);
	abstime.tv_sec  += milliseconds / 1000;
	abstime.tv_nsec += (milliseconds % 1000)*1000000;
	if (abstime.tv_nsec >= 1000000000)
	{
		abstime.tv_nsec -= 1000000000;
		abstime.tv_sec++;
	}
#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;
}


} // namespace Poco