<?php

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

namespace TYPO3\CMS\Core\Locking;

use TYPO3\CMS\Core\Locking\Exception\LockAcquireException;
use TYPO3\CMS\Core\Locking\Exception\LockAcquireWouldBlockException;
use TYPO3\CMS\Core\Locking\Exception\LockCreateException;

/**
 * Interface for locking methods
 */
interface LockingStrategyInterface
{
    /**
     * Exclusive locks can be acquired
     */
    const LOCK_CAPABILITY_EXCLUSIVE = 1;

    /**
     * Shared locks can be acquired
     */
    const LOCK_CAPABILITY_SHARED = 2;

    /**
     * Do not block when acquiring the lock
     */
    const LOCK_CAPABILITY_NOBLOCK = 4;

    /**
     * @return int LOCK_CAPABILITY_* elements combined with bit-wise OR
     */
    public static function getCapabilities();

    /**
     * @return int Returns a priority for the method. 0 to 100, 100 is highest
     */
    public static function getPriority();

    /**
     * @param string $subject ID to identify this lock in the system
     * @throws LockCreateException if the lock could not be created
     */
    public function __construct($subject);

    /**
     * Try to acquire a lock
     *
     * @param int $mode LOCK_CAPABILITY_EXCLUSIVE or LOCK_CAPABILITY_SHARED
     * @return bool Returns TRUE if the lock was acquired successfully
     * @throws LockAcquireException if the lock could not be acquired
     * @throws LockAcquireWouldBlockException if the acquire would have blocked and NOBLOCK was set
     */
    public function acquire($mode = self::LOCK_CAPABILITY_EXCLUSIVE);

    /**
     * Release the lock
     *
     * @return bool Returns TRUE on success or FALSE on failure
     */
    public function release();

    /**
     * Destroys the resource associated with the lock
     */
    public function destroy();

    /**
     * Get status of this lock
     *
     * @return bool Returns TRUE if lock is acquired by this locker, FALSE otherwise
     */
    public function isAcquired();
}
