sem_get
(PHP 4, PHP 5, PHP 7)
sem_get — Get a semaphore id
Description
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.
Parameters
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.
Return Values
Returns a positive semaphore identifier on success, or FALSE on error.
Notes
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.
See Also
- sem_acquire() - Acquire a semaphore
- sem_release() - Release a semaphore
- ftok() - Convert a pathname and a project identifier to a System V IPC key
← sem_acquire
sem_release →
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