Proposed mutex extension.

extensions/mutex/Mutex.php

+<?php
+
+namespace yii\mutex;
+
+use Yii;
+use yii\base\Component;
+
+abstract class Mutex extends Component
+{
+	public $autoRelease = true;
+
+	private $_locks = array();
+
+
+	public function init()
+	{
+		if ($this->autoRelease) {
+			register_shutdown_function(array($this, 'shutdownFunction'));
+		}
+	}
+
+	/**
+	 * NEVER CALL THIS METHOD UNDER ANY CIRCUMSTANCES
+	 */
+	public function shutdownFunction()
+	{
+		foreach ($this->_locks as $lock) {
+			$this->release($lock);
+		}
+	}
+
+	public function acquireLock($name, $timeout = 0)
+	{
+		if ($this->acquire($name, $timeout)) {
+			$this->_locks[] = $name;
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+	public function releaseLock($name)
+	{
+		if ($this->release($name)) {
+			unset($this->_locks[array_search($name, $this->_locks)]);
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+	public function getIsLockAcquired($name)
+	{
+		if (in_array($name, $this->_locks)) {
+			return true;
+		} else {
+			return $this->getIsAcquired($name);
+		}
+	}
+
+	public function getIsLockLocal($name)
+	{
+		return in_array($name, $this->_locks);
+	}
+
+	abstract protected function acquire($name, $timeout = 0);
+
+	abstract protected function release($name);
+
+	protected function getIsAcquired($name)
+	{
+		return null;
+	}
+
+	abstract public function getIsDistributed();
+}

extensions/mutex/db/Mutex.php

+<?php
+
+namespace yii\mutex\db;
+
+use Yii;
+use yii\db\Connection;
+use yii\base\InvalidConfigException;
+
+abstract class Mutex extends \yii\mutex\Mutex
+{
+	/**
+	 * @var string|Connection
+	 */
+	public $db = 'db';
+
+	public function init()
+	{
+		parent::init();
+		$this->db = Yii::$app->getComponent($this->db);
+		if (!$this->db instanceof Connection) {
+			throw new InvalidConfigException('');
+		}
+	}
+
+	public function getIsDistributed()
+	{
+		return true;
+	}
+}

extensions/mutex/db/mssql/Mutex.php

+<?php
+
+namespace yii\mutex\db\mssql;
+
+use Yii;
+use yii\base\InvalidConfigException;
+
+class Mutex extends \yii\mutex\db\Mutex
+{
+	public function init()
+	{
+		parent::init();
+		$driverName = $this->db->driverName;
+		if ($driverName !== 'sqlsrv' && $driverName !== 'dblib' && $driverName !== 'mssql') {
+			throw new InvalidConfigException('');
+		}
+	}
+
+	protected function acquire($name, $timeout = 0)
+	{
+		// http://msdn.microsoft.com/en-us/library/ms189823.aspx
+	}
+
+	protected function release($name)
+	{
+		// http://msdn.microsoft.com/en-us/library/ms178602.aspx
+	}
+}

extensions/mutex/db/mysql/Mutex.php

+<?php
+
+namespace yii\mutex\db\mysql;
+
+use Yii;
+use yii\base\InvalidConfigException;
+
+class Mutex extends \yii\mutex\db\Mutex
+{
+	public function init()
+	{
+		parent::init();
+		if ($this->db->driverName !== 'mysql') {
+			throw new InvalidConfigException('');
+		}
+	}
+
+	protected function acquire($name, $timeout = 0)
+	{
+		return (boolean)$this->db
+			->createCommand('SELECT GET_LOCK(:name, :timeout)', array(':name' => $name, ':timeout' => $timeout))
+			->queryScalar();
+	}
+
+	protected function release($name)
+	{
+		return (boolean)$this->db
+			->createCommand('SELECT RELEASE_LOCK(:name)', array(':name' => $name))
+			->queryScalar();
+	}
+
+	protected function getIsAcquired($name)
+	{
+		return (boolean)$this->db
+			->createCommand('SELECT IS_FREE_LOCK(:name)', array(':name' => $name))
+			->queryScalar();
+	}
+}

extensions/mutex/unix/Mutex.php

+<?php
+
+namespace yii\mutex\unix;
+
+use Yii;
+use yii\base\InvalidConfigException;
+
+class Mutex extends \yii\mutex\Mutex
+{
+	private $_files = array();
+
+
+	public function init()
+	{
+//		if (stripos(php_uname('s'), 'win') === 0) {
+//			throw new InvalidConfigException('');
+//		}
+	}
+
+	protected function acquire($name, $timeout = 0)
+	{
+		$file = fopen(Yii::$app->getRuntimePath() . '/mutex.' . md5($name) . '.lock', 'w+');
+		if ($file === false) {
+			return false;
+		}
+		$waitTime = 0;
+		while (!flock($file, LOCK_EX | LOCK_NB)) {
+			$waitTime++;
+			if ($waitTime > $timeout) {
+				fclose($file);
+				return false;
+			}
+			sleep(1);
+		}
+		$this->_files[$name] = $file;
+		return true;
+	}
+
+	protected function release($name)
+	{
+		if (!isset($this->_files[$name]) || !flock($this->_files[$name], LOCK_UN)) {
+			return false;
+		} else {
+			fclose($this->_files[$name]);
+			unset($this->_files[$name]);
+			return true;
+		}
+	}
+
+	protected function getIsAcquired($name)
+	{
+		return false;
+	}
+
+	public function getIsDistributed()
+	{
+		return false;
+	}
+}