(PECL sync >= 1.0.0)
SyncReaderWriter::writelock — Waits for an exclusive write lock
$wait = -1
) : boolObtains an exclusive write lock on a SyncReaderWriter object.
waitThe number of milliseconds to wait for a lock. A value of -1 is infinite.
成功时返回 true， 或者在失败时返回 false。
Example #1 SyncReaderWriter::writelock() example
<?php
$readwrite = new SyncReaderWriter("FileCacheLock");
$readwrite->writelock();
/* ... */
$readwrite->writeunlock();
?>