bool sem_acquire(resource $sem_identifier[, bool $nowait = false])
sem_acquire() by default blocks (if necessary) until the semaphore can be acquired. A process attempting to acquire a semaphore which it has already acquired will block forever if acquiring the semaphore would cause its maximum number of semaphore to be exceeded.
After processing a request, any semaphores acquired by the process but not explicitly released will be released automatically and a warning will be generated.
TRUE on success or
FALSE on failure.
- resource $sem_identifier:
sem_identifieris a semaphore resource, obtained from sem_get().
- bool $nowait [ = false]: Specifies if the process shouldn't wait for the semaphore to be acquired. If set to true, the call will return false immediately if a semaphore cannot be immediately acquired.