/**
* Get exclusive mutex for key. Key will be still accessible to read and write, but
* another process can exclude dog-pile effect, if before updating the key he will try to get this mutex.
* @param mixed $key
* @param mixed $auto_unlocker_variable - pass empty, just declared variable
* @return bool
*/
public function lock_key($key, &$auto_unlocker_variable)
{
$r = $this->redis->SetNX($this->lock_key_prefix . $key, 1);
if (!$r) {
return false;
}
$this->redis->Expire($this->lock_key_prefix . $key, $this->key_lock_time);
$auto_unlocker_variable = new KeyAutoUnlocker(array($this, 'unlock_key'));
$auto_unlocker_variable->setKey($key);
return true;
}
/**
* Get exclusive mutex for key. Key will be still accessible to read and write, but
* another process can exclude dog-pile effect, if before updating the key he will try to get this mutex.
* Example:
* Process 1 reads key simultaneously with Process 2.
* Value of this key are too old, so Process 1 going to refresh it. Simultaneously with Process 2.
* But both of them trying to lock_key, and Process 1 only will refresh value of key (taking it from database, e.g.),
* and Process 2 can decide, what he want to do - use old value and not spent time to database, or something else.
* @param mixed $key
* @param mixed $auto_unlocker_variable - pass empty, just declared variable
* @return bool
*/
public function lock_key($key, &$auto_unlocker_variable)
{
$r = apc_add($this->lock_key_prefix . $key, 1, $this->key_lock_time);
if (!$r) {
return false;
}
$auto_unlocker_variable = new KeyAutoUnlocker(array($this, 'unlock_key'));
$auto_unlocker_variable->setKey($key);
return true;
}