Your IP : 216.73.217.95
<?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;
/**
* A caching backend which stores cache entries by using APCu.
*
* The APCu backend is not very good with tagging and scales O(2n) with the
* number of tags. Do not use this backend if the data to be cached has many tags!
*
* This backend uses the following types of keys:
* - tag_xxx
* xxx is tag name, value is array of associated identifiers identifier. This
* is "forward" tag index. It is mainly used for obtaining content by tag
* (get identifier by tag -> get content by identifier)
* - ident_xxx
* xxx is identifier, value is array of associated tags. This is "reverse" tag
* index. It provides quick access for all tags associated with this identifier
* and used when removing the identifier
*
* Each key is prepended with a prefix. The prefix makes sure keys from the different
* installations do not conflict. By default, prefix consists from two parts
* separated by underscore character and ends in yet another underscore character:
* - "TYPO3"
* - Hash of path to TYPO3 and user running TYPO3
*/
final class ApcuBackend extends AbstractBackend implements TaggableBackendInterface, TransientBackendInterface
{
/**
* A prefix to separate stored data from other data possible stored in the APC.
*/
private string $identifierPrefix = '';
/**
* Constructs this backend
*
* @param string $context Unused, for backward compatibility only
* @param array $options Configuration options - unused here
* @throws Exception
*/
public function __construct($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);
}
/**
* Initializes the identifier prefix when setting the cache.
*/
public function setCache(FrontendInterface $cache): void
{
parent::setCache($cache);
$this->identifierPrefix = 'TYPO3_' . hash('xxh3', Environment::getProjectPath() . $this->context . $cache->getIdentifier()) . '_';
}
/**
* Saves data in the cache.
*
* @param string $entryIdentifier An identifier for this specific cache entry
* @param mixed $data The data to be stored
* @param array $tags Tags to associate with this cache entry
* @param int $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
* @throws Exception if no cache frontend has been set.
*/
public function set($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);
}
$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.');
}
}
/**
* Loads data from the cache.
*
* @param string $entryIdentifier An identifier which describes the cache entry to load
* @return mixed The cache entry's content as a string or FALSE if the cache entry could not be loaded
*/
public function get($entryIdentifier): mixed
{
$success = false;
$value = apcu_fetch($this->identifierPrefix . $entryIdentifier, $success);
return $success ? $value : $success;
}
/**
* Checks if a cache entry with the specified identifier exists.
*
* @param string $entryIdentifier An identifier specifying the cache entry
* @return bool TRUE if such an entry exists, FALSE if not
*/
public function has($entryIdentifier): bool
{
$success = false;
apcu_fetch($this->identifierPrefix . $entryIdentifier, $success);
return $success;
}
/**
* Removes all cache entries matching the specified identifier.
* Usually this only affects one entry but if - for what reason ever -
* old entries for the identifier still exist, they are removed as well.
*
* @param string $entryIdentifier Specifies the cache entry to remove
* @return bool TRUE if (at least) an entry could be removed or FALSE if no entry was found
*/
public function remove($entryIdentifier): bool
{
$this->removeIdentifierFromAllTags($entryIdentifier);
return apcu_delete($this->identifierPrefix . $entryIdentifier);
}
/**
* Finds and returns all cache entry identifiers which are tagged by the
* specified tag.
*
* @param string $tag The tag to search for
* @return array An array with identifiers of all matching entries. An empty array if no entries matched
*/
public function findIdentifiersByTag($tag): array
{
$success = false;
$identifiers = apcu_fetch($this->identifierPrefix . 'tag_' . $tag, $success);
if ($success === false) {
return [];
}
return (array)$identifiers;
}
/**
* Removes all cache entries of this cache.
*
* @throws Exception
*/
public function flush(): void
{
if (!$this->cache instanceof FrontendInterface) {
throw new Exception('Yet no cache frontend has been set via setCache().', 1232986571);
}
apcu_delete(new \APCUIterator('/^' . preg_quote($this->identifierPrefix, '/') . '/'));
}
/**
* Removes all cache entries of this cache which are tagged by the specified tag.
*
* @param string $tag The tag the entries must have
*/
public function flushByTag($tag): void
{
$identifiers = $this->findIdentifiersByTag($tag);
foreach ($identifiers as $identifier) {
$this->remove($identifier);
}
}
/**
* Associates the identifier with the given tags
*/
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);
}
}
/**
* Removes association of the identifier with the given tags
*/
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);
}
/**
* Finds all tags for the given identifier. This function uses reverse tag
* index to search for tags.
*/
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
}
}