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 //------------------------------------------------------------------------------ 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 //------------------------------------------------------------------------------ 47 CSemaphore::~CSemaphore() 48 { 49 pthread_mutex_destroy(&m_mutex); 50 pthread_cond_destroy(&m_cond); 51 } 52 53 54 //------------------------------------------------------------------------------ 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 //------------------------------------------------------------------------------ 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 //------------------------------------------------------------------------------ 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 //------------------------------------------------------------------------------ 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
