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/** @addtogroup MCD_MCDIMPL_DAEMON_SRV
* @{
* @file
*
* Semaphore implementation (pthread wrapper).
*
* Copyright (c) 2013 TRUSTONIC LIMITED
* 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. Neither the name of the TRUSTONIC LIMITED nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* 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 HOLDER 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 <time.h>
#include <limits.h>
#include "CSemaphore.h"
#include <stdio.h>
//------------------------------------------------------------------------------
CSemaphore::CSemaphore(int size) : m_waiters_count(0), m_count(size)
{
pthread_mutex_init(&m_mutex, NULL);
pthread_cond_init(&m_cond, NULL);
}
//------------------------------------------------------------------------------
CSemaphore::~CSemaphore()
{
pthread_mutex_destroy(&m_mutex);
pthread_cond_destroy(&m_cond);
}
//------------------------------------------------------------------------------
void CSemaphore::wait()
{
pthread_mutex_lock(&m_mutex);
m_waiters_count ++;
while ( m_count == 0 )
pthread_cond_wait(&m_cond, &m_mutex);
m_waiters_count --;
m_count --;
pthread_mutex_unlock(&m_mutex);
}
//------------------------------------------------------------------------------
bool CSemaphore::wait(int sec)
{
int rc = 0;
struct timespec tm;
if (sec < 0)
sec = LONG_MAX;
clock_gettime(CLOCK_REALTIME, &tm);
tm.tv_sec += sec;
pthread_mutex_lock(&m_mutex);
m_waiters_count ++;
if ( m_count == 0 ) {
rc = pthread_cond_timedwait(&m_cond, &m_mutex, &tm);
}
m_waiters_count --;
// Decrement only if waiting actually succeeded, otherwise we
// just timed out
if (!rc)
m_count --;
pthread_mutex_unlock(&m_mutex);
return (rc == 0);
}
//------------------------------------------------------------------------------
bool CSemaphore::wouldWait()
{
bool ret = false;
pthread_mutex_lock(&m_mutex);
if ( m_count == 0 )
ret = true;
pthread_mutex_unlock(&m_mutex);
return ret;
}
//------------------------------------------------------------------------------
void CSemaphore::signal()
{
pthread_mutex_lock(&m_mutex);
if ( m_waiters_count > 0 )
pthread_cond_signal(&m_cond);
m_count ++;
pthread_mutex_unlock(&m_mutex);
}
/** @} */
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