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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Defines abstract factory class for generating locks.
*
* @package core
* @copyright Damyon Wiese 2013
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core\lock;
defined('MOODLE_INTERNAL') || die();
/**
* Defines abstract factory class for generating locks.
*
* @package core
* @category lock
* @copyright Damyon Wiese 2013
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface lock_factory {
/**
* Define the constructor signature required by the lock_config class.
*
* @param string $type - The type this lock is used for (e.g. cron, cache)
*/
public function __construct($type);
/**
* Return information about the blocking behaviour of the locks on this platform.
*
* @return boolean - False if attempting to get a lock will block indefinitely.
*/
public function supports_timeout();
/**
* Will this lock be automatically released when the process ends.
* This should never be relied upon in code - but is useful in the case of
* fatal errors. If a lock type does not support this auto release,
* the max lock time parameter must be obeyed to eventually clean up a lock.
*
* @return boolean - True if this lock type will be automatically released when the current process ends.
*/
public function supports_auto_release();
/**
* Supports recursion.
*
* @return boolean - True if attempting to get 2 locks on the same resource will "stack"
*/
public function supports_recursion();
/**
* Is available.
*
* @return boolean - True if this lock type is available in this environment.
*/
public function is_available();
/**
* Get a lock within the specified timeout or return false.
*
* @param string $resource - The identifier for the lock. Should use frankenstyle prefix.
* @param int $timeout - The number of seconds to wait for a lock before giving up.
* Not all lock types will support this.
* @param int $maxlifetime - The number of seconds to wait before reclaiming a stale lock.
* Not all lock types will use this - e.g. if they support auto releasing
* a lock when a process ends.
* @return \core\lock\lock|boolean - An instance of \core\lock\lock if the lock was obtained, or false.
*/
public function get_lock($resource, $timeout, $maxlifetime = 86400);
/**
* Release a lock that was previously obtained with @lock.
*
* @param lock $lock - The lock to release.
* @return boolean - True if the lock is no longer held (including if it was never held).
*/
public function release_lock(lock $lock);
/**
* Extend the timeout on a held lock.
*
* @param lock $lock - lock obtained from this factory
* @param int $maxlifetime - new max time to hold the lock
* @return boolean - True if the lock was extended.
*/
public function extend_lock(lock $lock, $maxlifetime = 86400);
}