midcom_services_cache_module

Complexity

Total Complexity

15

Size/Duplication

Total Lines	125
Duplicated Lines	0 %

Test Coverage

Coverage

53.33%

Importance

Changes	1
Bugs	0	Features	0

4 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	4	1
B	prepare_backend()	0	34	9
A	invalidate_all()	0	5	2
A	_create_backend()	0	18	3

<?php
/**
 * @package midcom.services
 * @author The Midgard Project, http://www.midgard-project.org
 * @copyright The Midgard Project, http://www.midgard-project.org
 * @license http://www.gnu.org/licenses/lgpl.html GNU Lesser General Public License
 */

use Doctrine\Common\Cache;
use Doctrine\Common\Cache\CacheProvider;

/**
 * This is the base class for the MidCOM cache modules. It provides a basic infrastructure
 * for building your own caching service, providing hooks for initialization.
 *
 * It provides convenience methods to start up the cache module, for example for the creation
 * of a cache backend instance. There is no specific initialization done during startup, to
 * allow the modules to do their own magic during startup (it is difficult to generalize such
 * stuff).
 *
 * @package midcom.services
 */
abstract class midcom_services_cache_module
{
    /**
     * A list of all backends created by _create_backend(). They will be automatically
     * shut down when the module shuts down. They are indexed by their name.
     *
     * @var Doctrine\Common\Cache\CacheProvider[]
     */
    private $_backends = [];

    /**
     * The cache key prefix.
     *
     * @var string
     */
    private $_prefix;

    /**
     * Cache backend instance.
     *
     * @var Doctrine\Common\Cache\CacheProvider
     */
    protected $backend;

    /**
     * Initialize the module. This will initialize the class configuration
     * and call the corresponding event handler.
     */
    public function __construct()
    {
        $this->_prefix = get_class($this) . $_SERVER['SERVER_NAME'];
        $this->backend = new Cache\VoidCache();
    }

    /**
     * Creates an instance of the handler described by the configuration passed to
     * the function.
     *
     * The configuration array must include the configuration parameters driver and
     * directory, as outlined in the midcom_services_cache_backend class documentation.
     *
     * All backends will be collected in the $_backends array, indexed by their name.
     *
     * Any duplicate instantiation will be intercepted, throwing a critical error.
     *
     * @param string $name The name of the backend, must be unique throughout the system.
     * @param array $config The configuration of the backend to create. It must contain
     *     the key 'driver', which indicates which backend to use.
     */
    protected function _create_backend($name, array $config) : CacheProvider
    {
        $name = $this->_prefix . $name;

        if (array_key_exists($name, $this->_backends)) {
            throw new midcom_error("Cannot create backend driver instance {$name}: A backend with this name does already exist.");
        }

        if (!array_key_exists('driver', $config)) {
            throw new midcom_error("Cannot create backend driver instance {$name}: The driver class is not specified in the configuration.");
        }

        $backend = $this->prepare_backend($config, $name);
        $backend->setNamespace($name);

        $this->_backends[$name] = $backend;

        return $backend;
    }

    private function prepare_backend(array $config, string $name) : CacheProvider
    {
        $directory = midcom::get()->getCacheDir();
        if (!empty($config['directory'])) {
            $directory .= '/' . $config['directory'];
        }

        switch ($config['driver']) {
            case 'apc':
                $backend = new Cache\ApcuCache();
                break;
            case 'memcached':
                if ($memcached = midcom_services_cache_module_memcache::prepare_memcached($config)) {
                    $backend = new Cache\MemcachedCache();
                    $backend->setMemcached($memcached);
                    break;
                }
                debug_add("memcache: Failed to connect. Falling back to filecache", MIDCOM_LOG_ERROR);
                // fall-through
            case 'dba':
            case 'flatfile':
                $backend = new Cache\FilesystemCache($directory . '/' . $name);
                break;
            case 'sqlite':
                $sqlite = new SQLite3("{$directory}/sqlite.db");
                $backend = new Cache\SQLite3Cache($sqlite, $name);
                break;
            case 'null':
            default:
                $backend = new Cache\VoidCache();
                break;
        }

        return $backend;
    }

    /**
     * Invalidate the cache completely, dropping all entries. The default implementation will
     * drop all entries from all registered cache backends using CacheProvider::flushAll().
     * Override this function if this behavior doesn't suit your needs.
     */
    public function invalidate_all()
    {
        foreach ($this->_backends as $name => $backend) {
            debug_add("Invalidating cache backend {$name}...", MIDCOM_LOG_INFO);
            $backend->flushAll();
        }
    }

    /**
     * Invalidate all cache objects related to the given GUID.
     *
     * @param string $guid The GUID that has to be invalidated.
     * @param object $object The object that has to be invalidated (if available).
     */
    abstract public function invalidate($guid, $object = null);
}