blocxx

IPCMutex.cpp

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00001 /*******************************************************************************
00002 * Copyright (C) 2005 Novell, Inc. All rights reserved.
00003 *
00004 * Redistribution and use in source and binary forms, with or without
00005 * modification, are permitted provided that the following conditions are met:
00006 *
00007 *  - Redistributions of source code must retain the above copyright notice,
00008 *    this list of conditions and the following disclaimer.
00009 *
00010 *  - Redistributions in binary form must reproduce the above copyright notice,
00011 *    this list of conditions and the following disclaimer in the documentation
00012 *    and/or other materials provided with the distribution.
00013 *
00014 *  - Neither the name of Novell, Inc., nor the names of its
00015 *    contributors may be used to endorse or promote products derived from this
00016 *    software without specific prior written permission.
00017 *
00018 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
00019 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00020 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00021 * ARE DISCLAIMED. IN NO EVENT SHALL Novell, Inc., OR THE 
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00028 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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00030 
00031 
00036 #include "blocxx/BLOCXX_config.h"
00037 
00038 #ifdef BLOCXX_GNU_LINUX
00039 #include "blocxx/IPCMutex.hpp"
00040 #include "blocxx/ExceptionIds.hpp"
00041 
00042 
00043 namespace BLOCXX_NAMESPACE
00044 {
00045 
00046 const int ADD_KEY = 1; 
00047 const int BLOCK_FOR_KEY = -1; 
00048 
00049 BLOCXX_DEFINE_EXCEPTION_WITH_ID(IPCMutex);
00050 
00051 
00053 IPCMutex::IPCMutex(int semKey)
00054 {
00055    m_sbuf.sem_num = 0; 
00056    m_sbuf.sem_flg = 0; 
00057    m_semid = semget((key_t)semKey, 1, 0666); 
00058    if (m_semid == -1)
00059    {
00060       m_semid = semget((key_t)semKey, 1, IPC_CREAT | 0666); 
00061       if (m_semid == -1)
00062       {
00063          BLOCXX_THROW(IPCMutexException, 
00064                    "Unable to create semaphore"); 
00065          return; 
00066       }
00067       m_arg.val = 1; 
00068       if (semctl(m_semid, 0, SETVAL, m_arg) != 0)
00069       {
00070          BLOCXX_THROW_ERRNO_MSG(IPCMutexException, 
00071             "semctl() failed"); 
00072       }
00073    }
00074 }
00075 
00077 void
00078 IPCMutex::wait()
00079 {
00080    m_sbuf.sem_op = BLOCK_FOR_KEY; 
00081    if (semop(m_semid, &m_sbuf, 1) != 0)
00082    {
00083       BLOCXX_THROW_ERRNO_MSG(IPCMutexException, 
00084          "Failed to wait on semaphore"); 
00085    }
00086 }
00087 
00089 void
00090 IPCMutex::signal()
00091 {
00092    m_sbuf.sem_op = ADD_KEY; 
00093    if (semop(m_semid, &m_sbuf, 1) != 0)
00094    {
00095       BLOCXX_THROW_ERRNO_MSG(IPCMutexException, 
00096          "Failed to signal semaphore"); 
00097    }
00098 }
00099 
00101 // static 
00102 void
00103 IPCMutex::free(int semKey)
00104 {
00105    int semid = semget((key_t)semKey, 1, 0666); 
00106    if (semid != -1)
00107    {
00108       semctl(semid, 1, IPC_RMID, 0); 
00109    }
00110 }
00111 
00113 IPCMutexLock::IPCMutexLock(IPCMutex& sem)
00114 : m_sem(sem)
00115 {
00116    m_sem.wait(); 
00117 }
00118 
00120 IPCMutexLock::~IPCMutexLock()
00121 {
00122    m_sem.signal(); 
00123 }
00124 
00125 }
00126 
00127 #endif // BLOCXX_GNU_LINUX