SyncMutex::unlock

(PECL sync >= 1.0.0)

SyncMutex::unlock — Unlocks the mutex

说明

public SyncMutex::unlock ( bool $all = false ) : bool

Decreases the internal counter of a SyncMutex object. When the internal counter reaches zero, the actual lock on the object is released.

参数

all: Specifies whether or not to set the internal counter to zero and therefore release the lock.

返回值

成功时返回 true，或者在失败时返回 false。

范例

Example #1 SyncMutex::unlock() example


<?php
$mutex = new SyncMutex("UniqueName");

$mutex->lock();

/* ... */

$mutex->unlock();
?>

参见

SyncMutex::lock() - Waits for an exclusive lock

User Contributed Notes

npelov at croler dot net 10-May-2020 09:18


If the php process dies unexpectedly (on linux) the lock will remain with no option to remove it. unlock() will not work if the lock is being held by other process. SyncMutex uses shared mem. in that case you can delete the shared memory object in /dev/shm. To list the objects:



ls /dev/shm/Sync_Mutex*



Keep in mind that objects remain there even after unlocking. So if you use lots of random mutex names then the number of these objects will grow and and you might want to cleanup at some point



Example sync.php:

<?php



$s = new SyncMutex("mymutex");



if(!$s->lock()){

  echo "cannot lock\n";

  exit;

}

echo "locked\n";

sleep(10);

$s->unlock();

echo "unlocked\n";

?>



then run:



php -f sync.php



and press ctrl-c. If you run it again it won't lock. So what you can do is:



rm -f /dev/shm/Sync_Mutex-*-mymutex



Then run it again - it'll lock again