resource sem_get(int $key[, int $max_acquire = 1, int $perm = 0666, int $auto_release = 1])
When using sem_get() to access a semaphore created outside PHP, note that the semaphore must have been created as a set of 3 semaphores (for example, by specifying 3 as the nsems parameter when calling the C semget() function), otherwise PHP will be unable to access the semaphore.
sem_get() returns an id that can be used to access the System V semaphore with the given
A second call to sem_get() for the same key will return a different semaphore identifier, but both identifiers access the same underlying semaphore.
Returns a positive semaphore identifier on success, or
FALSE on error.
- int $key:
- int $max_acquire [ = 1]: The number of processes that can acquire the semaphore simultaneously is set to
- int $perm [ = 0666]: The semaphore permissions. Actually this value is set only if the process finds it is the only process currently attached to the semaphore.
- int $auto_release [ = 1]: Specifies if the semaphore should be automatically released on request shutdown.