Add a way for packagers to override some installation details

[mediawiki.git] / includes / filerepo / RepoGroup.php

<?php
/**
 * Prioritized list of file repositories.
 *
 * 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
 * @ingroup FileRepo
 */

/**
 * Prioritized list of file repositories
 *
 * @ingroup FileRepo
 */
class RepoGroup {
        /**
         * @var LocalRepo
         */
        var $localRepo;

        var $foreignRepos, $reposInitialised = false;
        var $localInfo, $foreignInfo;
        var $cache;

        /**
         * @var RepoGroup
         */
        protected static $instance;
        const MAX_CACHE_SIZE = 500;

        /**
         * Get a RepoGroup instance. At present only one instance of RepoGroup is
         * needed in a MediaWiki invocation, this may change in the future.
         * @return RepoGroup
         */
        static function singleton() {
                if ( self::$instance ) {
                        return self::$instance;
                }
                global $wgLocalFileRepo, $wgForeignFileRepos;
                self::$instance = new RepoGroup( $wgLocalFileRepo, $wgForeignFileRepos );
                return self::$instance;
        }

        /**
         * Destroy the singleton instance, so that a new one will be created next
         * time singleton() is called.
         */
        static function destroySingleton() {
                self::$instance = null;
        }

        /**
         * Set the singleton instance to a given object
         * Used by extensions which hook into the Repo chain.
         * It's not enough to just create a superclass ... you have
         * to get people to call into it even though all they know is RepoGroup::singleton()
         *
         * @param $instance RepoGroup
         */
        static function setSingleton( $instance ) {
                self::$instance = $instance;
        }

        /**
         * Construct a group of file repositories.
         *
         * @param $localInfo array Associative array for local repo's info
         * @param $foreignInfo Array of repository info arrays.
         *     Each info array is an associative array with the 'class' member
         *     giving the class name. The entire array is passed to the repository
         *     constructor as the first parameter.
         */
        function __construct( $localInfo, $foreignInfo ) {
                $this->localInfo = $localInfo;
                $this->foreignInfo = $foreignInfo;
                $this->cache = array();
        }

        /**
         * Search repositories for an image.
         * You can also use wfFindFile() to do this.
         *
         * @param $title Title|string Title object or string
         * @param $options array Associative array of options:
         *     time:           requested time for an archived image, or false for the
         *                     current version. An image object will be returned which was
         *                     created at the specified time.
         *
         *     ignoreRedirect: If true, do not follow file redirects
         *
         *     private:        If true, return restricted (deleted) files if the current
         *                     user is allowed to view them. Otherwise, such files will not
         *                     be found.
         *
         *     bypassCache:    If true, do not use the process-local cache of File objects
         * @return File object or false if it is not found
         */
        function findFile( $title, $options = array() ) {
                if ( !is_array( $options ) ) {
                        // MW 1.15 compat
                        $options = array( 'time' => $options );
                }
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }
                $title = File::normalizeTitle( $title );
                if ( !$title ) {
                        return false;
                }

                # Check the cache
                if ( empty( $options['ignoreRedirect'] )
                        && empty( $options['private'] )
                        && empty( $options['bypassCache'] ) )
                {
                        $time = isset( $options['time'] ) ? $options['time'] : '';
                        $dbkey = $title->getDBkey();
                        if ( isset( $this->cache[$dbkey][$time] ) ) {
                                wfDebug( __METHOD__.": got File:$dbkey from process cache\n" );
                                # Move it to the end of the list so that we can delete the LRU entry later
                                $this->pingCache( $dbkey );
                                # Return the entry
                                return $this->cache[$dbkey][$time];
                        }
                        $useCache = true;
                } else {
                        $useCache = false;
                }

                # Check the local repo
                $image = $this->localRepo->findFile( $title, $options );

                # Check the foreign repos
                if ( !$image ) {
                        foreach ( $this->foreignRepos as $repo ) {
                                $image = $repo->findFile( $title, $options );
                                if ( $image ) {
                                        break;
                                }
                        }
                }

                $image = $image ? $image : false; // type sanity
                # Cache file existence or non-existence
                if ( $useCache && ( !$image || $image->isCacheable() ) ) {
                        $this->trimCache();
                        $this->cache[$dbkey][$time] = $image;
                }

                return $image;
        }

        /**
         * @param $inputItems array
         * @return array
         */
        function findFiles( $inputItems ) {
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }

                $items = array();
                foreach ( $inputItems as $item ) {
                        if ( !is_array( $item ) ) {
                                $item = array( 'title' => $item );
                        }
                        $item['title'] = File::normalizeTitle( $item['title'] );
                        if ( $item['title'] ) {
                                $items[$item['title']->getDBkey()] = $item;
                        }
                }

                $images = $this->localRepo->findFiles( $items );

                foreach ( $this->foreignRepos as $repo ) {
                        // Remove found files from $items
                        foreach ( $images as $name => $image ) {
                                unset( $items[$name] );
                        }

                        $images = array_merge( $images, $repo->findFiles( $items ) );
                }
                return $images;
        }

        /**
         * Interface for FileRepo::checkRedirect()
         * @param $title Title
         * @return bool
         */
        function checkRedirect( Title $title ) {
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }

                $redir = $this->localRepo->checkRedirect( $title );
                if( $redir ) {
                        return $redir;
                }
                foreach ( $this->foreignRepos as $repo ) {
                        $redir = $repo->checkRedirect( $title );
                        if ( $redir ) {
                                return $redir;
                        }
                }
                return false;
        }

        /**
         * Find an instance of the file with this key, created at the specified time
         * Returns false if the file does not exist.
         *
         * @param $hash String base 36 SHA-1 hash
         * @param $options array Option array, same as findFile()
         * @return File object or false if it is not found
         */
        function findFileFromKey( $hash, $options = array() ) {
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }

                $file = $this->localRepo->findFileFromKey( $hash, $options );
                if ( !$file ) {
                        foreach ( $this->foreignRepos as $repo ) {
                                $file = $repo->findFileFromKey( $hash, $options );
                                if ( $file ) break;
                        }
                }
                return $file;
        }

        /**
         * Find all instances of files with this key
         *
         * @param $hash String base 36 SHA-1 hash
         * @return Array of File objects
         */
        function findBySha1( $hash ) {
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }

                $result = $this->localRepo->findBySha1( $hash );
                foreach ( $this->foreignRepos as $repo ) {
                        $result = array_merge( $result, $repo->findBySha1( $hash ) );
                }
                return $result;
        }

        /**
         * Get the repo instance with a given key.
         * @param $index string|int
         * @return bool|LocalRepo
         */
        function getRepo( $index ) {
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }
                if ( $index === 'local' ) {
                        return $this->localRepo;
                } elseif ( isset( $this->foreignRepos[$index] ) ) {
                        return $this->foreignRepos[$index];
                } else {
                        return false;
                }
        }

        /**
         * Get the repo instance by its name
         * @param $name string
         * @return bool
         */
        function getRepoByName( $name ) {
                if ( !$this->reposInitialised ) {
                        $this->initialiseRepos();
                }
                foreach ( $this->foreignRepos as $repo ) {
                        if ( $repo->name == $name ) {
                                return $repo;
                        }
                }
                return false;
        }

        /**
         * Get the local repository, i.e. the one corresponding to the local image
         * table. Files are typically uploaded to the local repository.
         *
         * @return LocalRepo
         */
        function getLocalRepo() {
                return $this->getRepo( 'local' );
        }

        /**
         * Call a function for each foreign repo, with the repo object as the
         * first parameter.
         *
         * @param $callback Callback: the function to call
         * @param $params Array: optional additional parameters to pass to the function
         * @return bool
         */
        function forEachForeignRepo( $callback, $params = array() ) {
                foreach( $this->foreignRepos as $repo ) {
                        $args = array_merge( array( $repo ), $params );
                        if( call_user_func_array( $callback, $args ) ) {
                                return true;
                        }
                }
                return false;
        }

        /**
         * Does the installation have any foreign repos set up?
         * @return Boolean
         */
        function hasForeignRepos() {
                return (bool)$this->foreignRepos;
        }

        /**
         * Initialise the $repos array
         */
        function initialiseRepos() {
                if ( $this->reposInitialised ) {
                        return;
                }
                $this->reposInitialised = true;

                $this->localRepo = $this->newRepo( $this->localInfo );
                $this->foreignRepos = array();
                foreach ( $this->foreignInfo as $key => $info ) {
                        $this->foreignRepos[$key] = $this->newRepo( $info );
                }
        }

        /**
         * Create a repo class based on an info structure
         */
        protected function newRepo( $info ) {
                $class = $info['class'];
                return new $class( $info );
        }

        /**
         * Split a virtual URL into repo, zone and rel parts
         * @param $url string
         * @throws MWException
         * @return array containing repo, zone and rel
         */
        function splitVirtualUrl( $url ) {
                if ( substr( $url, 0, 9 ) != 'mwrepo://' ) {
                        throw new MWException( __METHOD__.': unknown protocol' );
                }

                $bits = explode( '/', substr( $url, 9 ), 3 );
                if ( count( $bits ) != 3 ) {
                        throw new MWException( __METHOD__.": invalid mwrepo URL: $url" );
                }
                return $bits;
        }

        /**
         * @param $fileName string
         * @return array
         */
        function getFileProps( $fileName ) {
                if ( FileRepo::isVirtualUrl( $fileName ) ) {
                        list( $repoName, /* $zone */, /* $rel */ ) = $this->splitVirtualUrl( $fileName );
                        if ( $repoName === '' ) {
                                $repoName = 'local';
                        }
                        $repo = $this->getRepo( $repoName );
                        return $repo->getFileProps( $fileName );
                } else {
                        return FSFile::getPropsFromPath( $fileName );
                }
        }

        /**
         * Move a cache entry to the top (such as when accessed)
         */
        protected function pingCache( $key ) {
                if ( isset( $this->cache[$key] ) ) {
                        $tmp = $this->cache[$key];
                        unset( $this->cache[$key] );
                        $this->cache[$key] = $tmp;
                }
        }

        /**
         * Limit cache memory
         */
        protected function trimCache() {
                while ( count( $this->cache ) >= self::MAX_CACHE_SIZE ) {
                        reset( $this->cache );
                        $key = key( $this->cache );
                        wfDebug( __METHOD__.": evicting $key\n" );
                        unset( $this->cache[$key] );
                }
        }

        /**
         * Clear RepoGroup process cache used for finding a file
         * @param $title Title|null Title of the file or null to clear all files
         */
        public function clearCache( Title $title = null ) {
                if ( $title == null ) {
                        $this->cache = array();
                } else {
                        $dbKey = $title->getDBkey();
                        if ( isset( $this->cache[$dbKey] ) ) {
                                unset( $this->cache[$dbKey] );
                        }
                }
        }
}