SessionManager: Change behavior of getSessionById()

[mediawiki.git] / includes / cache / MessageBlobStore.php

<?php
/**
 * Message blobs storage used by ResourceLoader.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @author Roan Kattouw
 * @author Trevor Parscal
 * @author Timo Tijhof
 */

use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;

/**
 * This class generates message blobs for use by ResourceLoader modules.
 *
 * A message blob is a JSON object containing the interface messages for a certain module in
 * a certain language.
 */
class MessageBlobStore implements LoggerAwareInterface {

        /* @var ResourceLoader|null */
        private $resourceloader;

        /**
         * @var LoggerInterface
         */
        protected $logger;

        /**
         * @var WANObjectCache
         */
        protected $wanCache;

        /**
         * @param ResourceLoader $rl
         * @param LoggerInterface $logger
         */
        public function __construct( ResourceLoader $rl = null, LoggerInterface $logger = null ) {
                $this->resourceloader = $rl;
                $this->logger = $logger ?: new NullLogger();
                $this->wanCache = ObjectCache::getMainWANInstance();
        }

        /**
         * @since 1.27
         * @param LoggerInterface $logger
         */
        public function setLogger( LoggerInterface $logger ) {
                $this->logger = $logger;
        }

        /**
         * Get the message blob for a module
         *
         * @since 1.27
         * @param ResourceLoaderModule $module
         * @param string $lang Language code
         * @return string JSON
         */
        public function getBlob( ResourceLoaderModule $module, $lang ) {
                $blobs = $this->getBlobs( array( $module->getName() => $module ), $lang );
                return $blobs[$module->getName()];
        }

        /**
         * Get the message blobs for a set of modules
         *
         * @since 1.27
         * @param ResourceLoaderModule[] $modules Array of module objects keyed by name
         * @param string $lang Language code
         * @return array An array mapping module names to message blobs
         */
        public function getBlobs( array $modules, $lang ) {
                // Each cache key for a message blob by module name and language code also has a generic
                // check key without language code. This is used to invalidate any and all language subkeys
                // that exist for a module from the updateMessage() method.
                $cache = $this->wanCache;
                $checkKeys = array(
                        // Global check key, see clear()
                        $cache->makeKey( __CLASS__ )
                );
                $cacheKeys = array();
                foreach ( $modules as $name => $module ) {
                        $cacheKey = $this->makeCacheKey( $module, $lang );
                        $cacheKeys[$name] = $cacheKey;
                        // Per-module check key, see updateMessage()
                        $checkKeys[$cacheKey][] = $cache->makeKey( __CLASS__, $name );
                }
                $curTTLs = array();
                $result = $cache->getMulti( array_values( $cacheKeys ), $curTTLs, $checkKeys );

                $blobs = array();
                foreach ( $modules as $name => $module ) {
                        $key = $cacheKeys[$name];
                        if ( !isset( $result[$key] ) || $curTTLs[$key] === null || $curTTLs[$key] < 0 ) {
                                $this->logger->info( 'Message blob cache-miss for {module}',
                                        array( 'module' => $name, 'cacheKey' => $key )
                                );
                                $blobs[$name] = $this->recacheMessageBlob( $key, $module, $lang );
                        } else {
                                // Use unexpired cache
                                $blobs[$name] = $result[$key];
                        }
                }
                return $blobs;
        }

        /**
         * @deprecated since 1.27 Use getBlobs() instead
         * @return array
         */
        public function get( ResourceLoader $resourceLoader, $modules, $lang ) {
                return $this->getBlobs( $modules, $lang );
        }

        /**
         * @deprecated since 1.27 Obsolete. Used to populate a cache table in the database.
         * @return bool
         */
        public function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
                return false;
        }

        /**
         * @since 1.27
         * @param ResourceLoaderModule $module
         * @param string $lang
         * @return string Cache key
         */
        private function makeCacheKey( ResourceLoaderModule $module, $lang ) {
                $messages = array_values( array_unique( $module->getMessages() ) );
                sort( $messages );
                return $this->wanCache->makeKey( __CLASS__, $module->getName(), $lang,
                        md5( json_encode( $messages ) )
                );
        }

        /**
         * @since 1.27
         * @param string $cacheKey
         * @param ResourceLoaderModule $module
         * @param string $lang
         * @return string JSON blob
         */
        protected function recacheMessageBlob( $cacheKey, ResourceLoaderModule $module, $lang ) {
                $blob = $this->generateMessageBlob( $module, $lang );
                $cache = $this->wanCache;
                $cache->set( $cacheKey, $blob,
                        // Add part of a day to TTL to avoid all modules expiring at once
                        $cache::TTL_WEEK + mt_rand( 0, $cache::TTL_DAY ),
                        Database::getCacheSetOptions( wfGetDB( DB_SLAVE ) )
                );
                return $blob;
        }

        /**
         * Invalidate cache keys for modules using this message key.
         * Called by MessageCache when a message has changed.
         *
         * @param string $key Message key
         */
        public function updateMessage( $key ) {
                $moduleNames = $this->getResourceLoader()->getModulesByMessage( $key );
                foreach ( $moduleNames as $moduleName ) {
                        // Uses a holdoff to account for database slave lag (for MessageCache)
                        $this->wanCache->touchCheckKey( $this->wanCache->makeKey( __CLASS__, $moduleName ) );
                }
        }

        /**
         * Invalidate cache keys for all known modules.
         * Called by LocalisationCache after cache is regenerated.
         */
        public function clear() {
                $cache = $this->wanCache;
                // Disable holdoff because this invalidates all modules and also not needed since
                // LocalisationCache is stored outside the database and doesn't have lag.
                $cache->touchCheckKey( $cache->makeKey( __CLASS__ ), $cache::HOLDOFF_NONE );
        }

        /**
         * @since 1.27
         * @return ResourceLoader
         */
        protected function getResourceLoader() {
                // Back-compat: This class supports instantiation without a ResourceLoader object.
                // Lazy-initialise this property because most callers don't need it.
                if ( $this->resourceloader === null ) {
                        $this->logger->warning( __CLASS__ . ' created without a ResourceLoader instance' );
                        $this->resourceloader = new ResourceLoader();
                }
                return $this->resourceloader;
        }

        /**
         * @since 1.27
         * @param string $key Message key
         * @param string $lang Language code
         * @return string
         */
        protected function fetchMessage( $key, $lang ) {
                $message = wfMessage( $key )->inLanguage( $lang );
                $value = $message->plain();
                if ( !$message->exists() ) {
                        $this->logger->warning( 'Failed to find {messageKey} ({lang})', array(
                                'messageKey' => $key,
                                'lang' => $lang,
                        ) );
                }
                return $value;
        }

        /**
         * Generate the message blob for a given module in a given language.
         *
         * @param ResourceLoaderModule $module
         * @param string $lang Language code
         * @return string JSON blob
         */
        private function generateMessageBlob( ResourceLoaderModule $module, $lang ) {
                $messages = array();
                foreach ( $module->getMessages() as $key ) {
                        $messages[$key] = $this->fetchMessage( $key, $lang );
                }

                $json = FormatJson::encode( (object)$messages );
                if ( $json === false ) {
                        $this->logger->warning( 'Failed to encode message blob for {module} ({lang})', array(
                                'module' => $module->getName(),
                                'lang' => $lang,
                        ) );
                        $json = '{}';
                }
                return $json;
        }
}