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 //------------------------------------------------------------------------------
CSemaphore(int size)39 CSemaphore::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 //------------------------------------------------------------------------------
~CSemaphore()47 CSemaphore::~CSemaphore()
48 {
49 pthread_mutex_destroy(&m_mutex);
50 pthread_cond_destroy(&m_cond);
51 }
52
53
54 //------------------------------------------------------------------------------
wait()55 void 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 //------------------------------------------------------------------------------
wait(int sec)67 bool 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 //------------------------------------------------------------------------------
wouldWait()92 bool 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 //------------------------------------------------------------------------------
signal()104 void 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