ApcuBackend.php

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<?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\Cache\Backend;
 
use ‪TYPO3\CMS\Core\Cache\Exception;
use ‪TYPO3\CMS\Core\Cache\Frontend\FrontendInterface;
use ‪TYPO3\CMS\Core\Core\Environment;
 
final class ‪ApcuBackend extends ‪AbstractBackend implements ‪TaggableBackendInterface, ‪TransientBackendInterface
{
    private string ‪$identifierPrefix = '';
 
    public function ‪__construct(‪$context, array $options = [])
    {
        if (!extension_loaded('apcu')) {
            throw new ‪Exception('The PHP extension "apcu" must be installed and loaded in order to use the APCu backend.', 1232985914);
        }
        if (PHP_SAPI === 'cli' && ini_get('apc.enable_cli') == 0) {
            throw new ‪Exception('The APCu backend cannot be used because apcu is disabled on CLI.', 1232985915);
        }
        parent::__construct(‪$context, $options);
    }
 
    public function ‪setCache(‪FrontendInterface ‪$cache): void
    {
        parent::setCache(‪$cache);
        $this->identifierPrefix = 'TYPO3_' . hash('xxh3', ‪Environment::getProjectPath() . $this->context . ‪$cache->‪getIdentifier()) . '_';
    }
 
    public function set($entryIdentifier, $data, array $tags = [], $lifetime = null): void
    {
        if (!$this->cache instanceof ‪FrontendInterface) {
            throw new ‪Exception('No cache frontend has been set yet via setCache().', 1232986118);
        }
        $tags[] = '%APCBE%' . ‪$this->cacheIdentifier;
        $expiration = $lifetime ?? ‪$this->defaultLifetime;
        $success = apcu_store($this->identifierPrefix . $entryIdentifier, $data, $expiration);
        if ($success === true) {
            $this->‪removeIdentifierFromAllTags($entryIdentifier);
            $this->‪addIdentifierToTags($entryIdentifier, $tags);
        } else {
            $this->logger->alert('Error using APCu: Could not save data in the cache.');
        }
    }
 
    public function get($entryIdentifier): mixed
    {
        $success = false;
        $value = apcu_fetch($this->identifierPrefix . $entryIdentifier, $success);
        return $success ? $value : $success;
    }
 
    public function ‪has($entryIdentifier): bool
    {
        $success = false;
        apcu_fetch($this->identifierPrefix . $entryIdentifier, $success);
        return $success;
    }
 
    public function remove($entryIdentifier): bool
    {
        $this->‪removeIdentifierFromAllTags($entryIdentifier);
        return apcu_delete($this->identifierPrefix . $entryIdentifier);
    }
 
    public function ‪findIdentifiersByTag($tag): array
    {
        $success = false;
        $identifiers = apcu_fetch($this->identifierPrefix . 'tag_' . $tag, $success);
        if ($success === false) {
            return [];
        }
        return (array)$identifiers;
    }
 
    public function ‪flush(): void
    {
        if (!$this->cache instanceof ‪FrontendInterface) {
            throw new ‪Exception('Yet no cache frontend has been set via setCache().', 1232986571);
        }
        $this->‪flushByTag('%APCBE%' . $this->cacheIdentifier);
    }
 
    public function ‪flushByTag($tag): void
    {
        $identifiers = $this->‪findIdentifiersByTag($tag);
        foreach ($identifiers as ‪$identifier) {
            $this->remove(‪$identifier);
        }
    }
 
    private function ‪addIdentifierToTags(string $entryIdentifier, array $tags): void
    {
        // 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[] = $entryIdentifier;
                apcu_store($this->identifierPrefix . '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 ($existingTagsUpdated) {
            apcu_store($this->identifierPrefix . 'ident_' . $entryIdentifier, $existingTags);
        }
    }
 
    private function ‪removeIdentifierFromAllTags(string $entryIdentifier): void
    {
        // Get tags for this identifier
        $tags = $this->‪findTagsByIdentifier($entryIdentifier);
        // De-associate 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)) {
                    apcu_store($this->identifierPrefix . 'tag_' . $tag, $identifiers);
                } else {
                    apcu_delete($this->identifierPrefix . 'tag_' . $tag);
                }
            }
        }
        // Clear reverse tag index for this identifier
        apcu_delete($this->identifierPrefix . 'ident_' . $entryIdentifier);
    }
 
    private function ‪findTagsByIdentifier(string ‪$identifier): array
    {
        $success = false;
        $tags = apcu_fetch($this->identifierPrefix . 'ident_' . ‪$identifier, $success);
        return $success ? (array)$tags : [];
    }
 
    public function ‪collectGarbage(): void
    {
        // Noop, APCu has internal GC
    }
}