ProccessManagementTask.php

<?php
App::uses('WorkerTask', 'Console/Command');

/**
 * ProccessManagement Task
 *
 * Helps with CLI handling of mutex and signals
 *
 * IMPORTANT:
 *
 * Remember to add the following code at the top of Config/bootstrap.php
 * if you do not, signal handling will fail silently
 *
 * ```
 * if (php_sapi_name() === 'cli') {
 *	declare(ticks = 1);
 * }
 * ```
 */
class ProccessManagementTask extends AppShell {

/**
 * We need our lock file to be stored as a class property so it
 * won't get free()'d because there is no reference to it.
 *
 * That would free the lock on the file too :)
 *
 * @var resource
 */
	protected $_lockHandle;

/**
 * Make sure to get exclusive right to run this process, based on a file
 *
 * Should be used together with ProccessManagement->getLockFile()
 *
 * @param string $lockFile
 * @return void
 */
	public function mutex($lockFile) {
		$this->log(sprintf('Using lock file: %s', $lockFile), 'info');

		$this->_lockHandle = fopen($lockFile, 'w+');
		if (!flock($this->_lockHandle, LOCK_EX | LOCK_NB)) {
			$this->log(sprintf('Could not get exclusive lock, other process must be running'), 'warning');
			$this->_stop(-1);
		}
	}

/**
 * Get a lock file based on Nodes best practices
 *
 * The identifier should be something unique and static for each process
 *
 * @param Object $class The primary invoked Shell
 * @param string $identifier A unique identifier
 * @return string
 */
	public function getLockFile(Object $class, $identifier) {
		return $lockFile = sprintf('/tmp/%s_%s_%s.lock', Nodes\Environment::getProjectName(), get_class($class), $identifier);
	}

/**
 * Register signals and when they are triggered, write a Signal.shutdown property
 *
 * REMEMBER TO HAVE declare(ticks = 1); in the top of your Config/bootstrap.php file
 *
 * @return void
 */
	public function signals() {
		Configure::write('Signal.shutdown', false);

		$this->log('Installing signal handlers', 'info');

		pcntl_signal(SIGTERM, array($this, "sig_handler"));
		pcntl_signal(SIGHUP, array($this, "sig_handler"));
		pcntl_signal(SIGUSR1, array($this, "sig_handler"));
		pcntl_signal(SIGUSR2, array($this, "sig_handler"));
	}

/**
 * Simply set a Signal flag and do nothing more
 *
 * @param integer $signo
 * @return void
 */
	public function sig_handler($signo) {
		Configure::write('Signal.shutdown', true);
	}
}

sample.php

/**
 * Starts a Gearman worker long-living process
 *
 * @return void
 **/
	public function server() {
		$identifier = isset($this->params['process_id']) ? $this->params['process_id'] : 'cli';

		$this->ProccessManagement->mutex($this->ProccessManagement->getLockFile($this, $identifier));
		$this->ProccessManagement->signals();