/**
* @param string $point_name
* @param \Jamm\Memory\KeyAutoUnlocker $ExitWatcher set variable here to get Watcher into scope.
* When this object will be destructed, event will be generated, to catch exiting from scope of function or loop.
* @see http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization
* @return \Jamm\Memory\KeyAutoUnlocker
*/
public function setWatchedPoint($point_name, \Jamm\Memory\KeyAutoUnlocker &$ExitWatcher = NULL)
{
$this->setPoint($point_name);
if (empty($ExitWatcher)) {
$ExitWatcher = new \Jamm\Memory\KeyAutoUnlocker(array($this, 'watchFunctionExit'));
}
$ExitWatcher->setKey($point_name);
return $ExitWatcher;
}
/**
* 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 $auto_unlocker_variable - pass empty, just declared variable
*/
public function lock_key($key, &$auto_unlocker_variable)
{
$auto_unlocker = NULL;
if (!$this->sem->get_access_write($auto_unlocker)) {
return false;
}
$this->readmemory();
$key = (string) $key;
if (isset($this->mem[self::map_key_locks][$key])) {
return false;
}
$this->mem[self::map_key_locks][$key] = 1;
if ($this->refresh()) {
$auto_unlocker_variable = new \Jamm\Memory\KeyAutoUnlocker(array($this, 'unlock_key'));
$auto_unlocker_variable->setKey($key);
return true;
} else {
return false;
}
}
/**
* 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 $auto_unlocker_variable - pass empty, just declared variable
*/
public function lock_key($key, &$auto_unlocker_variable)
{
$r = $this->mem_object->add(self::lock_key_prefix . $key, 1, $this->key_lock_time);
if (!$r) {
return false;
}
$auto_unlocker_variable = new \Jamm\Memory\KeyAutoUnlocker(array($this, 'unlock_key'));
$auto_unlocker_variable->setKey($key);
return true;
}