FileLock.php

<?php

/** 
 * This has the same interface as the previous FileLock but supports multiple locks.
 * This allows you to run x processes at the same time.
 */
class FileLock {

	public $lockFile = null;

	public $config = array();

	public function __construct($config = array()) {
		$this->config = $config + array(
			'format' => 'file{:num}.lock',
			'file' => null,
			'max' => 5,
		);
	}

	public function __destruct() {
		$this->cleanup();
	}

	public function lock() {
		$this->lockFile = $this->findEmptyLock();
		file_put_contents($this->lockFile, time());
	}

	public function unlock() {
		$this->lockFile && unlink($this->lockFile);
	}

	/**
	 * You are only locked if all potential lock files exist.
	 */
	public function isLocked() {
		return !$this->findEmptyLock();
	}

	protected function findEmptyLock() {
		return $this->iterateLocks(function($lock) {
			if (!file_exists($lock)) {
				return $lock;
			}
			return false;
		});
	}

	/**
	 * Will allow you to iterate all the potential lock files.
	 * The first `trueish` value returns breaks the iteration cycle.
	 *
	 * @return mixed The trueish value the callback returns or `false`.
	 */
	protected function iterateLocks($callback) {
		$max = $this->config['max'];
		$format = $this->config['format'];
		for ($i = 0; $i<$max;$i++) {
			if ($value = $callback(str_replace('{:num}', $i, $format))) {
				return $value;
			}
		}
		return false;
	}

	/**
	 * Clean's up dead lock files.
	 *
	 * @param int $age The max age of a lock file.
	 * @return bool True
	 */
	public function cleanup($age = 600) {
		$this->iterateLocks(function($lock) {
			$time = file_exists($lock) ? (int) file_get_contents($lock) : time();
			if ($time + $age < time()) {
				unlink($lock);
			}
		});
		return true;
	}

}