ApcBackend.php

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<?php
namespace TYPO3\CMS\Core\Cache\Backend;

/*
 * 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\Utility\GeneralUtility;

class ApcBackend extends \TYPO3\CMS\Core\Cache\Backend\AbstractBackend implements \TYPO3\CMS\Core\Cache\Backend\TaggableBackendInterface
{
    protected $identifierPrefix;

    protected function setIdentifierPrefix($identifierPrefix)
    {
        $this->identifierPrefix = $identifierPrefix;
    }

    protected function getIdentifierPrefix()
    {
        return $this->identifierPrefix;
    }

    public function __construct($context, array $options = [])
    {
        if (!extension_loaded('apc')) {
            throw new \TYPO3\CMS\Core\Cache\Exception('The PHP extension "apc" or "apcu" must be installed and loaded in order to use the APC backend.', 1232985414);
        }
        if (PHP_SAPI === 'cli' && ini_get('apc.enable_cli') == 0) {
            throw new \TYPO3\CMS\Core\Cache\Exception('The APC backend cannot be used because apc is disabled on CLI.', 1232985415);
        }
        parent::__construct($context, $options);
    }

    public function setCache(\TYPO3\CMS\Core\Cache\Frontend\FrontendInterface $cache)
    {
        parent::setCache($cache);
        $processUser = $this->getCurrentUserData();
        $pathHash = \TYPO3\CMS\Core\Utility\GeneralUtility::shortMD5($this->getPathSite() . $processUser['name'] . $this->context . $cache->getIdentifier(), 12);
        $this->setIdentifierPrefix('TYPO3_' . $pathHash);
    }

    protected function getCurrentUserData()
    {
        return extension_loaded('posix') ? posix_getpwuid(posix_geteuid()) : ['name' => 'default'];
    }

    protected function getPathSite()
    {
        return PATH_site;
    }

    public function set($entryIdentifier, $data, array $tags = [], $lifetime = null)
    {
        if (!$this->cache instanceof \TYPO3\CMS\Core\Cache\Frontend\FrontendInterface) {
            throw new \TYPO3\CMS\Core\Cache\Exception('No cache frontend has been set yet via setCache().', 1232986818);
        }
        if (!is_string($data)) {
            throw new \TYPO3\CMS\Core\Cache\Exception\InvalidDataException('The specified data is of type "' . gettype($data) . '" but a string is expected.', 1232986825);
        }
        $tags[] = '%APCBE%' . $this->cacheIdentifier;
        $expiration = $lifetime !== null ? $lifetime : $this->defaultLifetime;
        $success = apc_store($this->getIdentifierPrefix() . $entryIdentifier, $data, $expiration);
        if ($success === true) {
            $this->removeIdentifierFromAllTags($entryIdentifier);
            $this->addIdentifierToTags($entryIdentifier, $tags);
        } else {
            $errorMessage = 'Error using APCu: Could not save data in the cache.';
            GeneralUtility::sysLog($errorMessage, 'core', GeneralUtility::SYSLOG_SEVERITY_ERROR);
        }
    }

    public function get($entryIdentifier)
    {
        $success = false;
        $value = apc_fetch($this->getIdentifierPrefix() . $entryIdentifier, $success);
        return $success ? $value : $success;
    }

    public function has($entryIdentifier)
    {
        $success = false;
        apc_fetch($this->getIdentifierPrefix() . $entryIdentifier, $success);
        return $success;
    }

    public function remove($entryIdentifier)
    {
        $this->removeIdentifierFromAllTags($entryIdentifier);
        return apc_delete($this->getIdentifierPrefix() . $entryIdentifier);
    }

    public function findIdentifiersByTag($tag)
    {
        $success = false;
        $identifiers = apc_fetch($this->getIdentifierPrefix() . 'tag_' . $tag, $success);
        if ($success === false) {
            return [];
        }
        return (array)$identifiers;
    }

    protected function findTagsByIdentifier($identifier)
    {
        $success = false;
        $tags = apc_fetch($this->getIdentifierPrefix() . 'ident_' . $identifier, $success);
        return $success ? (array)$tags : [];
    }

    public function flush()
    {
        if (!$this->cache instanceof \TYPO3\CMS\Core\Cache\Frontend\FrontendInterface) {
            throw new \TYPO3\CMS\Core\Cache\Exception('Yet no cache frontend has been set via setCache().', 1232986971);
        }
        $this->flushByTag('%APCBE%' . $this->cacheIdentifier);
    }

    public function flushByTag($tag)
    {
        $identifiers = $this->findIdentifiersByTag($tag);
        foreach ($identifiers as $identifier) {
            $this->remove($identifier);
        }
    }

    protected function addIdentifierToTags($entryIdentifier, array $tags)
    {
        // Get identifier-to-tag index to look for updates
        $existingTags = $this->findTagsByIdentifier($entryIdentifier);
        $existingTagsUpdated = false;

        foreach ($tags as $tag) {
            // Update tag-to-identifier index
            $identifiers = $this->findIdentifiersByTag($tag);
            if (!in_array($entryIdentifier, $identifiers, true)) {
                $identifiers[] = $entryIdentifier;
                apc_store($this->getIdentifierPrefix() . 'tag_' . $tag, $identifiers);
            }
            // Test if identifier-to-tag index needs update
            if (!in_array($tag, $existingTags, true)) {
                $existingTags[] = $tag;
                $existingTagsUpdated = true;
            }
        }

        // Update identifier-to-tag index if needed
        if ($existingTagsUpdated) {
            apc_store($this->getIdentifierPrefix() . 'ident_' . $entryIdentifier, $existingTags);
        }
    }

    protected function removeIdentifierFromAllTags($entryIdentifier)
    {
        // Get tags for this identifier
        $tags = $this->findTagsByIdentifier($entryIdentifier);
        // Deassociate tags with this identifier
        foreach ($tags as $tag) {
            $identifiers = $this->findIdentifiersByTag($tag);
            // Formally array_search() below should never return FALSE due to
            // the behavior of findTagsByIdentifier(). But if reverse index is
            // corrupted, we still can get 'FALSE' from array_search(). This is
            // not a problem because we are removing this identifier from
            // anywhere.
            if (($key = array_search($entryIdentifier, $identifiers)) !== false) {
                unset($identifiers[$key]);
                if (!empty($identifiers)) {
                    apc_store($this->getIdentifierPrefix() . 'tag_' . $tag, $identifiers);
                } else {
                    apc_delete($this->getIdentifierPrefix() . 'tag_' . $tag);
                }
            }
        }
        // Clear reverse tag index for this identifier
        apc_delete($this->getIdentifierPrefix() . 'ident_' . $entryIdentifier);
    }

    public function collectGarbage()
    {
    }
}