ApcBackend.php

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

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

    protected function getPathSite() {
        return PATH_site;
    }

    public function set($entryIdentifier, $data, array $tags = array(), $lifetime = NULL) {
        if (!$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 {
            throw new \TYPO3\CMS\Core\Cache\Exception('Could not set value.', 1232986877);
        }
    }

    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 array();
        } else {
            return (array) $identifiers;
        }
    }

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

    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[$key]);
                if (count($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() {

    }

}