This is achieved by using a "lock" mechanism. Each possibly concurrent thread cooperates by acquiring
a lock before accessing the corresponding data.
Usage example:
if ($mutex->acquire($mutexName)) {
business logic execution
} else {
execution is blocked!
}
This is a base class, which should be extended in order to implement the actual lock mechanism.
/**
* Initializes MySQL specific mutex component implementation.
* @throws InvalidConfigException if [[db]] is not MySQL connection.
*/
public function init()
{
parent::init();
if ($this->db->driverName !== 'mysql') {
throw new InvalidConfigException('In order to use MysqlMutex connection must be configured to use MySQL database.');
}
}
/**
* Initializes generic database table based mutex implementation.
* @throws InvalidConfigException if [[db]] is invalid.
*/
public function init()
{
parent::init();
if (is_string($this->db)) {
$this->db = Yii::$app->getComponent($this->db);
}
if (!$this->db instanceof Connection) {
throw new InvalidConfigException('Mutex::db must be either a DB connection instance or the application component ID of a DB connection.');
}
}
/**
* Initializes generic database table based mutex implementation.
* @throws InvalidConfigException if [[db]] is invalid.
*/
public function init()
{
parent::init();
$this->db = Instance::ensure($this->db, Connection::className());
}
/**
* Acquires current action lock.
* @return boolean lock acquiring result.
*/
protected function acquireMutex()
{
$this->mutex = Instance::ensure($this->mutex, Mutex::className());
return $this->mutex->acquire($this->composeMutexName());
}
/**
* @return \yii\mutex\Mutex
* @throws \yii\base\InvalidConfigException
*/
protected function getMutex()
{
return Instance::ensure($this->mutexID, Mutex::className());
}
/**
* @inheritdoc
*/
public function init()
{
parent::init();
$this->cache = is_string($this->cache) ? Yii::$app->get($this->cache, false) : $this->cache;
}