QueueBus.php

<?php
/**
 * @author Robin Appelman <icewind@owncloud.com>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OC\Command;

use OCP\Command\IBus;
use OCP\Command\ICommand;

class QueueBus implements IBus {
	/**
	 * @var (ICommand|callable)[]
	 */
	private $queue = [];

	/**
	 * Schedule a command to be fired
	 *
	 * @param \OCP\Command\ICommand | callable $command
	 */
	public function push($command) {
		$this->queue[] = $command;
	}

	/**
	 * Require all commands using a trait to be run synchronous
	 *
	 * @param string $trait
	 */
	public function requireSync($trait) {
	}

	/**
	 * @param \OCP\Command\ICommand | callable $command
	 */
	private function runCommand($command) {
		if ($command instanceof ICommand) {
			// ensure the command can be serialized
			$serialized = \serialize($command);
			if (\strlen($serialized) > 4000) {
				throw new \InvalidArgumentException('Trying to push a command which serialized form can not be stored in the database (>4000 character)');
			}
			// allowed_classes => true: PHP's allowed_classes does not resolve interface
			// hierarchies, so passing ICommand::class (an interface) would produce
			// __PHP_Incomplete_Class. The serialized value was just produced from
			// $command above in this same method — it is a pure in-memory round-trip
			// and not an external attack surface.
			$unserialized = \unserialize($serialized, ['allowed_classes' => true]);
			$unserialized->handle();
		} else {
			$command();
		}
	}

	public function run() {
		while ($command = \array_shift($this->queue)) {
			$this->runCommand($command);
		}
	}
}