1/** @addtogroup MCD_MCDIMPL_DAEMON_SRV
2 * @{
3 * @file
4 *
5 * Semaphore implementation (pthread wrapper).
6 *
7 * <!-- Copyright Giesecke & Devrient GmbH 2009 - 2012 -->
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. The name of the author may not be used to endorse or promote
18 *    products derived from this software without specific prior
19 *    written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
22 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
25 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
27 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33#include <time.h>
34#include <limits.h>
35#include "CSemaphore.h"
36#include <stdio.h>
37
38//------------------------------------------------------------------------------
39CSemaphore::CSemaphore(int size) : m_waiters_count(0), m_count(size)
40{
41    pthread_mutex_init(&m_mutex, NULL);
42    pthread_cond_init(&m_cond, NULL);
43}
44
45
46//------------------------------------------------------------------------------
47CSemaphore::~CSemaphore()
48{
49    pthread_mutex_destroy(&m_mutex);
50    pthread_cond_destroy(&m_cond);
51}
52
53
54//------------------------------------------------------------------------------
55void CSemaphore::wait()
56{
57    pthread_mutex_lock(&m_mutex);
58    m_waiters_count ++;
59    while ( m_count == 0 )
60        pthread_cond_wait(&m_cond, &m_mutex);
61    m_waiters_count --;
62    m_count --;
63    pthread_mutex_unlock(&m_mutex);
64}
65
66//------------------------------------------------------------------------------
67bool CSemaphore::wait(int sec)
68{
69    int rc = 0;
70    struct timespec tm;
71    if (sec < 0)
72        sec = LONG_MAX;
73    clock_gettime(CLOCK_REALTIME, &tm);
74    tm.tv_sec += sec;
75
76    pthread_mutex_lock(&m_mutex);
77    m_waiters_count ++;
78    if ( m_count == 0 ) {
79        rc = pthread_cond_timedwait(&m_cond, &m_mutex, &tm);
80    }
81    m_waiters_count --;
82    // Decrement only if waiting actually succeeded, otherwise we
83    // just timed out
84    if (!rc)
85        m_count --;
86    pthread_mutex_unlock(&m_mutex);
87    return (rc == 0);
88}
89
90
91//------------------------------------------------------------------------------
92bool CSemaphore::wouldWait()
93{
94    bool ret = false;
95    pthread_mutex_lock(&m_mutex);
96    if ( m_count == 0 )
97        ret = true;
98    pthread_mutex_unlock(&m_mutex);
99    return ret;
100}
101
102
103//------------------------------------------------------------------------------
104void CSemaphore::signal()
105{
106    pthread_mutex_lock(&m_mutex);
107    if ( m_waiters_count > 0 )
108        pthread_cond_signal(&m_cond);
109    m_count ++;
110    pthread_mutex_unlock(&m_mutex);
111}
112
113/** @} */
114