XcacheBackend.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\Cache\Exception;

class XcacheBackend extends AbstractBackend implements TaggableBackendInterface
{
    protected $identifierPrefix;

    public function __construct($context, array $options = [])
    {
        if (!extension_loaded('xcache')) {
            throw new Exception(
                'The PHP extension "xcache" must be installed and loaded in order to use the xcache backend.',
                1363116592
            );
        }
        parent::__construct($context, $options);
    }

    public function set($entryIdentifier, $data, array $tags = [], $lifetime = null)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return;
        }
        if (!$this->cache instanceof \TYPO3\CMS\Core\Cache\Frontend\FrontendInterface) {
            throw new Exception(
                'No cache frontend has been set yet via setCache().',
                1363117491
            );
        }
        if (!is_string($data)) {
            throw new Exception\InvalidDataException(
                'The specified data is of type "' . gettype($data) . '" but a string is expected.',
                1363117435
            );
        }
        $tags[] = '%XCBE%' . $this->cache->getIdentifier();
        $expiration = $lifetime !== null ? $lifetime : $this->defaultLifetime;
        $success = xcache_set($this->identifierPrefix . $entryIdentifier, $data, $expiration);
        if ($success === true) {
            $this->removeIdentifierFromAllTags($entryIdentifier);
            $this->addIdentifierToTags($entryIdentifier, $tags);
        } else {
            throw new Exception(
                'Could not set value.',
                1363117507
            );
        }
    }

    public function get($entryIdentifier)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return false;
        }
        $value = xcache_get($this->identifierPrefix . $entryIdentifier);
        return $value ?: false;
    }

    public function has($entryIdentifier)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return false;
        }
        return xcache_isset($this->identifierPrefix . $entryIdentifier);
    }

    public function remove($entryIdentifier)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return false;
        }
        $this->removeIdentifierFromAllTags($entryIdentifier);
        return xcache_unset($this->identifierPrefix . $entryIdentifier);
    }

    public function findIdentifiersByTag($tag)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return [];
        }
        $identifiers = xcache_get($this->identifierPrefix . 'tag_' . $tag);
        return $identifiers ?: [];
    }

    protected function findTagsByIdentifier($identifier)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return [];
        }
        $tags = xcache_get($this->identifierPrefix . 'ident_' . $identifier);
        return $tags ?: [];
    }

    public function flush()
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return;
        }
        if (!$this->cache instanceof \TYPO3\CMS\Core\Cache\Frontend\FrontendInterface) {
            throw new Exception(
                'Yet no cache frontend has been set via setCache().',
                1363117531
            );
        }
        $this->flushByTag('%XCBE%' . $this->cache->getIdentifier());
    }

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

    protected function addIdentifierToTags($entryIdentifier, array $tags)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return;
        }

        // 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[] = $entryIdentifier;
                xcache_set($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 ($existingTagsUpdated) {
            xcache_set($this->identifierPrefix . 'ident_' . $entryIdentifier, $existingTags);
        }
    }

    protected function removeIdentifierFromAllTags($entryIdentifier)
    {
        if ($this->runningFromCliOrWrongConfiguration()) {
            return;
        }
        // Get tags for this identifier
        $tags = $this->findTagsByIdentifier($entryIdentifier);
        // Disassociate 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)) {
                    xcache_set($this->identifierPrefix . 'tag_' . $tag, $identifiers);
                } else {
                    xcache_unset($this->identifierPrefix . 'tag_' . $tag);
                }
            }
        }
        // Clear reverse tag index for this identifier
        xcache_unset($this->identifierPrefix . 'ident_' . $entryIdentifier);
    }

    public function collectGarbage()
    {
    }

    protected function runningFromCliOrWrongConfiguration()
    {
        $varSize = ini_get('xcache.var_size');
        return php_sapi_name() === 'cli' || empty($varSize);
    }
}