IPCMutex.cpp

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00030 
00031 
00036 #include "blocxx/BLOCXX_config.h"
00037 #include "blocxx/IPCMutex.hpp"
00038 #include "blocxx/ExceptionIds.hpp"
00039 
00040 
00041 namespace BLOCXX_NAMESPACE
00042 {
00043 
00044 const int ADD_KEY = 1; 
00045 const int BLOCK_FOR_KEY = -1; 
00046 
00047 BLOCXX_DEFINE_EXCEPTION_WITH_ID(IPCMutex);
00048 
00049 
00051 IPCMutex::IPCMutex(int semKey)
00052 {
00053    m_sbuf.sem_num = 0; 
00054    m_sbuf.sem_flg = 0; 
00055    m_semid = semget((key_t)semKey, 1, 0666); 
00056    if (m_semid == -1)
00057    {
00058       m_semid = semget((key_t)semKey, 1, IPC_CREAT | 0666); 
00059       if (m_semid == -1)
00060       {
00061          BLOCXX_THROW(IPCMutexException, 
00062                    "Unable to create semaphore"); 
00063          return; 
00064       }
00065       m_arg.val = 1; 
00066       semctl(m_semid, 0, SETVAL, m_arg); 
00067    }
00068 }
00069 
00071 void
00072 IPCMutex::wait()
00073 {
00074    m_sbuf.sem_op = BLOCK_FOR_KEY; 
00075    semop(m_semid, &m_sbuf, 1); 
00076 }
00077 
00079 void
00080 IPCMutex::signal()
00081 {
00082    m_sbuf.sem_op = ADD_KEY; 
00083    semop(m_semid, &m_sbuf, 1); 
00084 }
00085 
00087 // static 
00088 void
00089 IPCMutex::free(int semKey)
00090 {
00091    int semid = semget((key_t)semKey, 1, 0666); 
00092    if (semid != -1)
00093    {
00094       semctl(semid, 1, IPC_RMID, 0); 
00095    }
00096 }
00097 
00099 IPCMutexLock::IPCMutexLock(IPCMutex& sem)
00100 : m_sem(sem)
00101 {
00102    m_sem.wait(); 
00103 }
00104 
00106 IPCMutexLock::~IPCMutexLock()
00107 {
00108    m_sem.signal(); 
00109 }
00110 
00111 }

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