Simple lock managing mechanism

Lock.php

use Nette\Utils\Strings;

class Lock {

	/** @var string */
	protected $dir;

	/** @var array */
	protected $lockHandle = array();



	/**
	 * @param string $dir where to store lock files
	 */
	function __construct($dir) {
		$this->dir = $dir;
	}



	/**
	 * @param $key
	 * @param bool $blocking whether lock should wait or just return false when it tries to get exclusive lock
	 * @throws LockException
	 * @return bool
	 */
	public function lock($key, $blocking = true) {
		$filename = $this->getLockFilename($key);
		$handle = @fopen($filename, 'w+'); // @ - file may not exist
		if (!$handle) {
			$handle = fopen($filename, 'w+');
			if (!$handle) {
				throw new LockException('Could not create file: ' . $filename);
			}
		}

		$this->lockHandle[$key] = $handle;
		return flock($handle, $blocking ? LOCK_EX : LOCK_EX | LOCK_NB);
	}



	public function unlock($key) {
		if (isset($this->lockHandle[$key])) {
			flock($this->lockHandle[$key], LOCK_UN);
			fclose($this->lockHandle[$key]);
			unset($this->lockHandle[$key]);
		}
	}



	public function getLockFilename($key) {
		$key = Strings::webalize($key);
		return usedir($this->dir) . "/$key.lock";
	}



	public function isLocked($key) {
		$lock = $this->lock($key, false);
		if ($lock) {
			$this->unlock($key);
		}
		return !$lock;
	}

}

class LockException extends \Exception {

}