// routines to use it (p blocks, cond p does not)
// 1 on success, -1 fail
int vrpn_Semaphore::p()
{
#ifdef sgi
if (fUsingLock) {
if (ussetlock(l) != 1) {
perror("vrpn_Semaphore::p: ussetlock:");
return -1;
}
}
else {
if (uspsema(ps) != 1) {
perror("vrpn_Semaphore::p: uspsema:");
return -1;
}
}
#elif defined(_WIN32)
switch (WaitForSingleObject(hSemaphore, INFINITE)) {
case WAIT_OBJECT_0:
// got the resource
break;
case WAIT_TIMEOUT:
ALL_ASSERT(0, "vrpn_Semaphore::p: infinite wait time timed out!");
return -1;
break;
case WAIT_ABANDONED:
ALL_ASSERT(0, "vrpn_Semaphore::p: thread holding resource died");
return -1;
break;
case WAIT_FAILED:
// get error info from windows (from FormatMessage help page)
LPVOID lpMsgBuf;
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL,
GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
// Default language
(LPTSTR)&lpMsgBuf, 0, NULL);
fprintf(stderr,
"vrpn_Semaphore::p: error waiting for resource, "
"WIN32 WaitForSingleObject call caused the following error: %s",
(LPTSTR)lpMsgBuf);
// Free the buffer.
LocalFree(lpMsgBuf);
return -1;
break;
default:
ALL_ASSERT(0, "vrpn_Semaphore::p: unknown return code");
return -1;
}
#else
// Posix by default
if (sem_wait(semaphore) != 0) {
perror("vrpn_Semaphore::p: ");
return -1;
}
#endif
return 1;
}
void SemaphoreGuard::handleLockResult_(int result)
{
ALL_ASSERT(result >= 0, "Lock error!");
if (result == 1) {
locked_ = true;
}
}
/// @brief Unlocks the resource, if we have locked it.
void SemaphoreGuard::unlock()
{
if (locked_) {
int result = sem_.v();
ALL_ASSERT(result == 0, "failed to unlock semaphore!");
locked_ = false;
}
}
// 0 if it can't get the resource, 1 if it can
// -1 if fail
int vrpn_Semaphore::condP() {
int iRetVal=1;
#ifdef sgi
if (fUsingLock) {
// don't spin at all
iRetVal = uscsetlock(l, 0);
if (iRetVal<=0) {
perror("vrpn_Semaphore::condP: uscsetlock:");
return -1;
}
} else {
iRetVal = uscpsema(ps);
if (iRetVal<=0) {
perror("vrpn_Semaphore::condP: uscpsema:");
return -1;
}
}
#elif defined(_WIN32)
switch (WaitForSingleObject(hSemaphore, 0)) {
case WAIT_OBJECT_0:
// got the resource
break;
case WAIT_TIMEOUT:
// resource not free
iRetVal=0;
break;
case WAIT_ABANDONED:
ALL_ASSERT(0,"vrpn_Semaphore::condP: thread holding resource died");
return -1;
break;
case WAIT_FAILED:
// get error info from windows (from FormatMessage help page)
LPVOID lpMsgBuf;
FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM,
NULL, GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
// Default language
(LPTSTR) &lpMsgBuf, 0, NULL );
fprintf(stderr, "Semaphore::condP: error waiting for resource, "
"WIN32 WaitForSingleObject call caused the following error: %s", (LPTSTR) lpMsgBuf);
// Free the buffer.
LocalFree( lpMsgBuf );
return -1;
break;
default:
ALL_ASSERT(0,"vrpn_Semaphore::p: unknown return code");
return -1;
}
#else
// Posix by default
iRetVal = sem_trywait(semaphore);
if (iRetVal == 0) { iRetVal = 1;
} else if (errno == EAGAIN) { iRetVal = 0;
} else {
perror("vrpn_Semaphore::condP: ");
iRetVal = -1;
}
#endif
return iRetVal;
}
