apcu_clear_cache - PHP code example

How to Clear Caches With the PHP Function apcu_clear_cache

PHP’s APCu library can improve performance by caching data and reducing database calls. But it’s important to clear caches as often as possible to avoid a buildup of old information. In this article, Reintech’s PHP developer, Jeremy Clark, explains how to do it by using the built-in function apcu_clear_cache.

APCu is the official replacement for the outdated APC extension. APC provided both opcode caching (opcache) and object caching functionality. Since PHP 5.5 and later include their own opcache, APCu now only provides object caching functionality, which is what Drupal uses.

The apcu_clear_cache function clears the APCu data cache for a single application container. This includes both the user and system caches. APCu’s user cache stores a key/value pair, and the system cache, which holds the opcode cache, is per-process rather than shared memory.

If you’re unable to clear your cache using this method, you may need to change the shm_size in your service configuration. Otherwise, you’ll need to run a script or use the Clear Caches button in your Site Dashboard to clean your cache. If this doesn’t work, you may need to restart your server. Alternatively, you can use a third-party tool like CacheTool to connect to a FastCGI daemon (such as PHP-FPM) and operate on its cache.

apcu_clear_cache example

/** * Clear opcode caches to make sure that the * updated files are used in the following requests. */
    public static function clearOpcodeCache()
    {
        if (\function_exists('opcache_reset')) {
            opcache_reset();
        }

        if (\function_exists('apcu_clear_cache')) {
            apcu_clear_cache();
        }
    }

    /** * @param \Slim\Slim $app * * @return $this */
    public static function getBaseUrl($app)
    {
        $filename = (isset($_SERVER['SCRIPT_FILENAME']))
                ?

/** * Clear opcode caches to make sure that the * updated plugin files are used in the following requests. */
    private function clearOpcodeCache(): void
    {
        if (\function_exists('opcache_reset')) {
            opcache_reset();
        }

        if (\function_exists('apcu_clear_cache')) {
            apcu_clear_cache();
        }
    }

    private function assertPrefix(string $filename, string $prefix): void
    {
        if (strpos($filename, $prefix) !== 0) {
            throw new RuntimeException(sprintf('Detected invalid file/directory %s in the plugin zip: %s', $filename, $prefix));
        }
    }

    private function assertNoDirectoryTraversal(string $filename): void
    {

    public function clean($mode = Zend_Cache::CLEANING_MODE_ALL, $tags = array())
    {
        switch ($mode) {
            case Zend_Cache::CLEANING_MODE_ALL:
                return apcu_clear_cache();
                break;
            case Zend_Cache::CLEANING_MODE_OLD:
                $this->_log("Zend_Cache_Backend_Apcu::clean() : CLEANING_MODE_OLD is unsupported by the Apcu backend");
                break;
            case Zend_Cache::CLEANING_MODE_MATCHING_TAG:
            case Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG:
            case Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG:
                $this->_log(self::TAGS_UNSUPPORTED_BY_CLEAN_OF_APCU_BACKEND);
                break;
            default:
                Zend_Cache::throwException('Invalid mode for clean() method');

/** * Clear opcode caches to make sure that the * updated plugin files are used in the following requests. */
    private function clearOpcodeCache()
    {
        if (\function_exists('opcache_reset')) {
            opcache_reset();
        }

        if (\function_exists('apcu_clear_cache')) {
            apcu_clear_cache();
        }
    }

    /** * @param string $filename * @param string $prefix */
    private function assertPrefix($filename, $prefix)
    {
        if (strpos($filename, $prefix) !== 0) {
            throw new RuntimeException(sprintf('Detected invalid file/directory %s in the plugin zip: %s', $filename, $prefix));
        }

/** * Clear opcode caches to make sure that the * updated plugin files are used in the following requests. */
    private function clearOpcodeCache()
    {
        if (\function_exists('opcache_reset')) {
            opcache_reset();
        }

        if (\function_exists('apcu_clear_cache')) {
            apcu_clear_cache();
        }
    }

    /** * @param PluginStruct|LicenceStruct $plugin * * @throws RuntimeException * * @return PluginStruct */
    private function createPluginStruct($plugin)
    {

public function clearProxyCache()
    {
        $configuration = $this->emConfig;

        $metaDataCache = $configuration->getMetadataCacheImpl();
        if ($metaDataCache !== null && method_exists($metaDataCache, 'deleteAll')) {
            $metaDataCache->deleteAll();
        }

        // Clear the APCu cache because this may cause problems when attributes are removed         if (\function_exists('apcu_clear_cache')) {
            apcu_clear_cache();
        }

        // Clear Shopware Proxies / Classmaps / Container         $this->clearDirectory($this->hookProxyDir);

        // Clear Annotation file cache         $this->clearDirectory($this->modelProxyDir);
    }

    public function clearOpCache()
    {

    protected function doHave(string $id): bool
    {
        return apcu_exists($id);
    }

    protected function doClear(string $namespace): bool
    {
        return isset($namespace[0]) && class_exists(\APCUIterator::class, false) && ('cli' !== \PHP_SAPI || filter_var(\ini_get('apc.enable_cli'), \FILTER_VALIDATE_BOOL))
            ? apcu_delete(new \APCUIterator(sprintf('/^%s/', preg_quote($namespace, '/')), \APC_ITER_KEY))
            : apcu_clear_cache();
    }

    protected function doDelete(array $ids): bool
    {
        foreach ($ids as $id) {
            apcu_delete($id);
        }

        return true;
    }

/** * Clear opcode caches to make sure that the * updated plugin files are used in the following requests. */
    private function clearOpcodeCache(): void
    {
        if (\function_exists('opcache_reset')) {
            opcache_reset();
        }

        if (\function_exists('apcu_clear_cache')) {
            apcu_clear_cache();
        }
    }

    private function assertPrefix(string $filename, string $prefix): void
    {
        if (mb_strpos($filename, $prefix) !== 0) {
            throw new PluginExtractionException(
                sprintf(
                    'Detected invalid file/directory %s in the plugin zip: %s',
                    $filename,
                    $prefix
                )