sem_get
int$key,
[int$max_acquire = 1],
[int$permissions = 0666],
[bool$auto_release = true]
): SysvSemaphore|false
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.
If key is 0, a new private semaphore is created for each call to sem_get.
Parameters
- key
-
- max_acquire
-
The number of processes that can acquire the semaphore simultaneously is set to max_acquire.
- permissions
-
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.
Changelog
| Version | Description |
| 8.0.0 | On success, this function returns a SysvSemaphore instance now; previously, a resource was returned. |
| 8.0.0 | The type of auto_release has been changed from int to bool. |