(PHP 4, PHP 5, PHP 7)
sem_acquire — Acquire a semaphore
$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.
sem_identifier
sem_identifier is a semaphore resource,
obtained from sem_get().
nowaitSpecifies 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.
成功时返回 TRUE， 或者在失败时返回 FALSE。
| 版本 | 说明 |
|---|---|
| 5.6.1 |
The $nowait parameter was added.
|