EMutex.php

<?php
/**
 * EMutex
 *
 * This is the mutex extension V1.10 available here:
 * http://www.yiiframework.com/extension/mutex
 *
 * (Tabs replaced by spaces + empty lines removed)
 */
class EMutex extends CApplicationComponent
{

    public $mutexFile;

    private $_locks = array();

    public function init()
    {
        parent::init();

        if (null === $this->mutexFile)
        {
            $this->mutexFile = Yii::app()->getRuntimePath() . '/mutex.bin';
        }

    }

    public function lock($id, $timeout = 0)
    {

        $lockFileHandle = $this->_getLockFileHandle($id);
        if (flock($lockFileHandle, LOCK_EX))
        {
            $data = @unserialize(@file_get_contents($this->mutexFile));

            if (empty($data))
            {
                $data = array();
            }

            if (!isset($data[$id]) || ($data[$id][0] > 0 && $data[$id][0] + $data[$id][1] <= microtime(true)))
            {
                $data[$id] = array($timeout, microtime(true));
                array_push($this->_locks, $id);
                $result = (bool)file_put_contents($this->mutexFile, serialize($data));
            }
        }
        fclose($lockFileHandle);
        @unlink($this->_getLockFile($id));

        return isset($result) ? $result : false;
    }

    public function unlock($id = null)
    {
        if (null === $id && null === ($id = array_pop($this->_locks)))
        {
            throw new CException("No lock available that could be released. Make sure to setup a lock first.");
        }
        elseif (in_array($id, $this->_locks))
        {
            throw new CException("Don't define the id for a local lock. Only do it for locks that weren't created within the current request.");
        }

        $lockFileHandle = $this->_getLockFileHandle($id);
        if (flock($lockFileHandle, LOCK_EX))
        {
            $data = @unserialize(@file_get_contents($this->mutexFile));
            if (!empty($data) && isset($data[$id]))
            {
                unset($data[$id]);
                $result = (bool)file_put_contents($this->mutexFile, serialize($data));
            }
        }
        fclose($lockFileHandle);
        @unlink($this->_getLockFile($id));

        return isset($result) ? $result : false;
    }

    private function _getLockFile($id)
    {
        return "{$this->mutexFile}." . md5($id) . '.lock';
    }

    private function _getLockFileHandle($id)
    {
        return fopen($this->_getLockFile($id), 'a+b');
    }

}