C++ CSafeStatic::find方法代码示例

void CInterProcessLock::Unlock()
{
    if (m_Handle == kInvalidLockHandle) {
        NCBI_THROW(CInterProcessLockException, eNotLocked,
                   "Attempt to unlock not-yet-acquired lock");
    }
    CFastMutexGuard LOCK(s_ProcessLock);

    // Check that lock with specified name not already locked
    // in the current process.
    TLocks::iterator it = s_Locks->find(m_SystemName);
    _VERIFY(it != s_Locks->end());

    if ( it->second > 1 ) {
        // Just decrease reference counter
        it->second--;
        return;
    }

    // Release lock

#if defined(NCBI_OS_UNIX)

#  if defined(F_TLOCK)
    int res = lockf(m_Handle, F_ULOCK, 0);
#  elif defined(F_SETLK)
    struct flock lockparam;
    lockparam.l_type   = F_UNLCK;
    lockparam.l_whence = SEEK_SET;
    lockparam.l_start  = 0;
    lockparam.l_len    = 0;  /* whole file */
    int res = fcntl(m_Handle, F_SETLK, &lockparam);
#  else
#   error "No supported lock method.  Please port this code."
#  endif
    if ( res < 0 ) {
        NCBI_THROW(CInterProcessLockException, eUnlockError,
                   "Cannot release the lock");
    }
    close(m_Handle);
    
#elif defined(NCBI_OS_MSWIN)
    if ( !::ReleaseMutex(m_Handle) ) {
        NCBI_THROW(CInterProcessLockException, eUnlockError,
                   "Cannot release the lock");
    }
    ::CloseHandle(m_Handle);
#endif
    m_Handle = kInvalidLockHandle;
    s_Locks->erase(m_SystemName);
}

void CInterProcessLock::Lock(const CTimeout& timeout,
                             const CTimeout& granularity)
{
    CFastMutexGuard LOCK(s_ProcessLock);

    // Check that lock with specified name not already locked
    // in the current process.
    TLocks::iterator it = s_Locks->find(m_SystemName);

    if (m_Handle != kInvalidLockHandle) {
        // The lock is already set in this CInterProcessLock object,
        // just increase reference counter.
        _VERIFY(it != s_Locks->end());
        it->second++;
        return;
    } else {
        if (it != s_Locks->end()) {
            // The lock already exists in the current process.
            // We can use one CInterProcessLock object with
            // multiple Lock() calls, but not with different
            // CInterProcessLock objects. For example, on MS-Windows,
            // we cannot wait on the same mutex in the same thread.
            // So, two different objects can set locks simultaneously.
            // And for OS-compatibility we can do nothing here,
            // except throwing an exception.
            NCBI_THROW(CInterProcessLockException, eMultipleLocks,
                       "Attempt to lock already locked object " \
                       "in the same process");
        }
    }

    // Try to acquire a lock with specified timeout

#if defined(NCBI_OS_UNIX)

    // Open lock file
    mode_t perm = CDirEntry::MakeModeT(
        CDirEntry::fRead | CDirEntry::fWrite /* user */,
        CDirEntry::fRead | CDirEntry::fWrite /* group */,
        0, 0 /* other & special */);
    int fd = open(m_SystemName.c_str(), O_CREAT | O_RDWR, perm);
    if (fd == -1) {
        NCBI_THROW(CInterProcessLockException, eCreateError,
                   string("Error creating lockfile ") + m_SystemName + 
                   ": " + strerror(errno));
    }

    // Try to acquire the lock
    
    int x_errno = 0;
    
    if (timeout.IsInfinite()  ||  timeout.IsDefault()) {
        while ((x_errno = s_UnixLock(fd))) {
            if (errno != EAGAIN)
                break;
        }

    } else {
        unsigned long ms = timeout.GetAsMilliSeconds();
        if ( !ms ) {
            // Timeout == 0
            x_errno = s_UnixLock(fd);
        } else {
            // Timeout > 0
            unsigned long ms_gran;
            if ( granularity.IsInfinite()  ||
                 granularity.IsDefault() ) 
            {
                ms_gran = min(ms/5, (unsigned long)500);
            } else {
                ms_gran = granularity.GetAsMilliSeconds();
            }
            // Try to lock within specified timeout
            for (;;) {
                x_errno = s_UnixLock(fd);
                if ( !x_errno ) {
                    // Successfully locked
                    break;
                }
                if (x_errno != EACCES  &&
                    x_errno != EAGAIN ) {
                    // Error
                    break;
                }
                // Otherwise -- sleep granularity timeout
                unsigned long ms_sleep = ms_gran;
                if (ms_sleep > ms) {
                    ms_sleep = ms;
                }
                if ( !ms_sleep ) {
                     break;
                }
                SleepMilliSec(ms_sleep);
                ms -= ms_sleep;
            }
            // Timeout
            if ( !ms ) {
                close(fd);
                NCBI_THROW(CInterProcessLockException, eLockTimeout,
                           "The lock could not be acquired in the time " \
//.........这里部分代码省略.........