Semaphore Functions
PHP Manual

sem_acquire

Acquire a semaphore

Description

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.

Parameters

sem_identifier

sem_identifier is a semaphore resource, obtained from sem_get.

nowait

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.

Return Values

Returns TRUE on success or FALSE on failure.

Changelog

Version Description
5.6.1 The $nowait parameter was added.

See Also

  • sem_get
  • sem_release