Php/docs/function.sem-acquire

• PHP Manual
• Semaphore 函数
• Acquire a semaphore

sem_acquire

(PHP 4, PHP 5, PHP 7)

sem_acquire — Acquire a semaphore

说明

sem_acquire ( SysvSemaphore $semaphore [, bool $non_blocking = 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

semaphore

semaphore is a semaphore obtained from sem_get().

non_blocking

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
8.0.0	semaphore expects a SysvSemaphore instance now; previously, a resource was expected.

参见

• sem_get() - Get a semaphore id
• sem_release() - Release a semaphore