9.5/_simple_lock_strategy_8php_source.html

<?php

namespace ‪TYPO3\CMS\Core\Locking;


/*

 * 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!

 */


use ‪TYPO3\CMS\Core\Core\Environment;

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

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

use ‪TYPO3\CMS\Core\Security\BlockSerializationTrait;

use ‪TYPO3\CMS\Core\Utility\GeneralUtility;


class ‪SimpleLockStrategy implements ‪LockingStrategyInterface

{

    use ‪BlockSerializationTrait;


    const ‪FILE_LOCK_FOLDER = 'lock/';


    protected ‪$filePath;


    protected ‪$isAcquired = false;


    protected ‪$loops = 150;


    protected ‪$step = 200;


    public function ‪__construct($subject)

    {

        // Tests if the directory for simple locks is available.

        // If not, the directory will be created. The lock path is usually

        // below typo3temp/var, typo3temp/var itself should exist already (or getProjectPath . /var/ respectively)

        $path = ‪Environment::getVarPath() . '/' . ‪self::FILE_LOCK_FOLDER;

        if (!is_dir($path)) {

            // Not using mkdir_deep on purpose here, if typo3temp/var itself

            // does not exist, this issue should be solved on a different

            // level of the application.

            if (!GeneralUtility::mkdir($path)) {

                throw new ‪LockCreateException('Cannot create directory ' . $path, 1460976286);

            }

        }

        if (!is_writable($path)) {

            throw new ‪LockCreateException('Cannot write to directory ' . $path, 1460976340);

        }

        $this->filePath = $path . 'simple_' . md5((string)$subject);

    }


    public function ‪init(‪$loops = 0, ‪$step = 0)

    {

        $this->loops = (int)‪$loops;

        $this->step = (int)‪$step;

    }


    public function ‪__destruct()

    {

        $this->‪release();

    }


    public function ‪release()

    {

        if (!$this->‪isAcquired) {

            return true;

        }


        $success = true;

        if (

            GeneralUtility::isAllowedAbsPath($this->filePath)

            && GeneralUtility::isFirstPartOfStr($this->filePath, ‪Environment::getVarPath() . '/' . self::FILE_LOCK_FOLDER)

        ) {

            if (@unlink($this->filePath) === false) {

                $success = false;

            }

        }


        $this->‪isAcquired = false;

        return $success;

    }


    public function ‪isAcquired()

    {

        return ‪$this->isAcquired;

    }


    public static function ‪getCapabilities()

    {

        return self::LOCK_CAPABILITY_EXCLUSIVE | ‪self::LOCK_CAPABILITY_NOBLOCK;

    }


    public function ‪acquire($mode = self::LOCK_CAPABILITY_EXCLUSIVE)

    {

        if ($this->‪isAcquired) {

            return true;

        }


        if (file_exists($this->filePath)) {

            $maxExecutionTime = (int)ini_get('max_execution_time');

            $maxAge = time() - ($maxExecutionTime ?: 120);

            if (@filectime($this->filePath) < $maxAge) {

                // Remove stale lock file

                @unlink($this->filePath);

            }

        }


        $this->‪isAcquired = false;

        $wouldBlock = false;

        for ($i = 0; $i < ‪$this->loops; $i++) {

            $filePointer = @fopen($this->filePath, 'x');

            if ($filePointer !== false) {

                fclose($filePointer);

                GeneralUtility::fixPermissions($this->filePath);

                $this->‪isAcquired = true;

                break;

            }

            if ($mode & self::LOCK_CAPABILITY_NOBLOCK) {

                $wouldBlock = true;

                break;

            }

            usleep($this->step * 1000);

        }


        if ($mode & self::LOCK_CAPABILITY_NOBLOCK && !$this->‪isAcquired && $wouldBlock) {

            throw new LockAcquireWouldBlockException('Failed to acquire lock because the request would block.', 1460976403);

        }


        return ‪$this->isAcquired;

    }


    public static function ‪getPriority()

    {

        return 50;

    }


    public function ‪destroy()

    {

        @unlink($this->filePath);

    }

}