php 한글 메뉴얼 도움말 검색 사이트 Get a semaphore id [function.sem-get]

설명

resource sem_get ( int $key [, int $max_acquire = 1 [, int $perm = 0666 [, int $auto_release = 1 ]]] )

sem_get() returns an id that can be used to access the System V semaphore with the given key.

A second call to sem_get() for the same key will return a different semaphore identifier, but both identifiers access the same underlying semaphore.

인수

key
max_acquire: The number of processes that can acquire the semaphore simultaneously is set to max_acquire.
perm: The semaphore permissions. Actually this value is set only if the process finds it is the only process currently attached to the semaphore.
auto_release: Specifies if the semaphore should be automatically released on request shutdown.

반환값

Returns a positive semaphore identifier on success, or FALSE on error.

주의

Warning

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.

참고

sem_acquire() - Acquire a semaphore
sem_release() - Release a semaphore
ftok() - Convert a pathname and a project identifier to a System V IPC key