sem_acquire

(PHP 4, PHP 5, PHP 7)

sem_acquire — Acquire a semaphore

说明

sem_acquire ( resource $sem_identifier [, bool $nowait = FALSE ] ) : bool

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.

参数

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.

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE。

更新日志

版本 说明
5.6.1 The $nowait parameter was added.

参见

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