(PECL sync >= 1.0.0)
SyncSemaphore::lock — Decreases the count of the semaphore or waits
$wait = -1
) : boolDecreases the count of a SyncSemaphore object or waits until the semaphore becomes non-zero.
waitThe number of milliseconds to wait for the semaphore. A value of -1 is infinite.
成功时返回 true， 或者在失败时返回 false。
Example #1 SyncSemaphore::lock() example
<?php
$semaphore = new SyncSemaphore("LimitedResource_2clients", 2);
if (!$semaphore->lock(3000))
{
echo "Unable to lock semaphore.";
exit();
}
/* ... */
$semaphore->unlock();
?>