--- /dev/null
+<?php
+/**
+ * @defgroup ExternalStorage ExternalStorage
+ */
+
+/**
+ * Interface for data storage in external 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
+ */
+
+/**
+ * Constructor class for key/value blob data kept in external repositories.
+ *
+ * Objects in external stores are defined by a special URL. The URL is of
+ * the form "<store protocol>://<location>/<object name>". The protocol is used
+ * to determine what ExternalStoreMedium class is used. The location identifies
+ * particular storage instances or database clusters for store class to use.
+ *
+ * When an object is inserted into a store, the calling code uses a partial URL of
+ * the form "<store protocol>://<location>" and receives the full object URL on success.
+ * This is useful since object names can be sequential IDs, UUIDs, or hashes.
+ * Callers are not responsible for unique name generation.
+ *
+ * External repositories might be populated by maintenance/async
+ * scripts, thus partial moving of data may be possible, as well
+ * as the possibility to have any storage format (i.e. for archives).
+ *
+ * @ingroup ExternalStorage
+ */
+class ExternalStore {
+ /**
+ * Get an external store object of the given type, with the given parameters
+ *
+ * @param string $proto Type of external storage, should be a value in $wgExternalStores
+ * @param array $params Associative array of ExternalStoreMedium parameters
+ * @return ExternalStoreMedium|bool The store class or false on error
+ */
+ public static function getStoreObject( $proto, array $params = [] ) {
+ global $wgExternalStores;
+
+ if ( !$wgExternalStores || !in_array( $proto, $wgExternalStores ) ) {
+ return false; // protocol not enabled
+ }
+
+ $class = 'ExternalStore' . ucfirst( $proto );
+
+ // Any custom modules should be added to $wgAutoLoadClasses for on-demand loading
+ return class_exists( $class ) ? new $class( $params ) : false;
+ }
+
+ /**
+ * Fetch data from given URL
+ *
+ * @param string $url The URL of the text to get
+ * @param array $params Associative array of ExternalStoreMedium parameters
+ * @return string|bool The text stored or false on error
+ * @throws MWException
+ */
+ public static function fetchFromURL( $url, array $params = [] ) {
+ $parts = explode( '://', $url, 2 );
+ if ( count( $parts ) != 2 ) {
+ return false; // invalid URL
+ }
+
+ list( $proto, $path ) = $parts;
+ if ( $path == '' ) { // bad URL
+ return false;
+ }
+
+ $store = self::getStoreObject( $proto, $params );
+ if ( $store === false ) {
+ return false;
+ }
+
+ return $store->fetchFromURL( $url );
+ }
+
+ /**
+ * Fetch data from multiple URLs with a minimum of round trips
+ *
+ * @param array $urls The URLs of the text to get
+ * @return array Map from url to its data. Data is either string when found
+ * or false on failure.
+ */
+ public static function batchFetchFromURLs( array $urls ) {
+ $batches = [];
+ foreach ( $urls as $url ) {
+ $scheme = parse_url( $url, PHP_URL_SCHEME );
+ if ( $scheme ) {
+ $batches[$scheme][] = $url;
+ }
+ }
+ $retval = [];
+ foreach ( $batches as $proto => $batchedUrls ) {
+ $store = self::getStoreObject( $proto );
+ if ( $store === false ) {
+ continue;
+ }
+ $retval += $store->batchFetchFromURLs( $batchedUrls );
+ }
+ // invalid, not found, db dead, etc.
+ $missing = array_diff( $urls, array_keys( $retval ) );
+ if ( $missing ) {
+ foreach ( $missing as $url ) {
+ $retval[$url] = false;
+ }
+ }
+
+ return $retval;
+ }
+
+ /**
+ * Store a data item to an external store, identified by a partial URL
+ * The protocol part is used to identify the class, the rest is passed to the
+ * class itself as a parameter.
+ *
+ * @param string $url A partial external store URL ("<store type>://<location>")
+ * @param string $data
+ * @param array $params Associative array of ExternalStoreMedium parameters
+ * @return string|bool The URL of the stored data item, or false on error
+ * @throws MWException
+ */
+ public static function insert( $url, $data, array $params = [] ) {
+ $parts = explode( '://', $url, 2 );
+ if ( count( $parts ) != 2 ) {
+ return false; // invalid URL
+ }
+
+ list( $proto, $path ) = $parts;
+ if ( $path == '' ) { // bad URL
+ return false;
+ }
+
+ $store = self::getStoreObject( $proto, $params );
+ if ( $store === false ) {
+ return false;
+ } else {
+ return $store->store( $path, $data );
+ }
+ }
+
+ /**
+ * Like insert() above, but does more of the work for us.
+ * This function does not need a url param, it builds it by
+ * itself. It also fails-over to the next possible clusters
+ * provided by $wgDefaultExternalStore.
+ *
+ * @param string $data
+ * @param array $params Associative array of ExternalStoreMedium parameters
+ * @return string|bool The URL of the stored data item, or false on error
+ * @throws MWException
+ */
+ public static function insertToDefault( $data, array $params = [] ) {
+ global $wgDefaultExternalStore;
+
+ return self::insertWithFallback( (array)$wgDefaultExternalStore, $data, $params );
+ }
+
+ /**
+ * Like insert() above, but does more of the work for us.
+ * This function does not need a url param, it builds it by
+ * itself. It also fails-over to the next possible clusters
+ * as provided in the first parameter.
+ *
+ * @param array $tryStores Refer to $wgDefaultExternalStore
+ * @param string $data
+ * @param array $params Associative array of ExternalStoreMedium parameters
+ * @return string|bool The URL of the stored data item, or false on error
+ * @throws MWException
+ */
+ public static function insertWithFallback( array $tryStores, $data, array $params = [] ) {
+ $error = false;
+ while ( count( $tryStores ) > 0 ) {
+ $index = mt_rand( 0, count( $tryStores ) - 1 );
+ $storeUrl = $tryStores[$index];
+ wfDebug( __METHOD__ . ": trying $storeUrl\n" );
+ list( $proto, $path ) = explode( '://', $storeUrl, 2 );
+ $store = self::getStoreObject( $proto, $params );
+ if ( $store === false ) {
+ throw new MWException( "Invalid external storage protocol - $storeUrl" );
+ }
+ try {
+ $url = $store->store( $path, $data ); // Try to save the object
+ } catch ( Exception $error ) {
+ $url = false;
+ }
+ if ( strlen( $url ) ) {
+ return $url; // Done!
+ } else {
+ unset( $tryStores[$index] ); // Don't try this one again!
+ $tryStores = array_values( $tryStores ); // Must have consecutive keys
+ wfDebugLog( 'ExternalStorage',
+ "Unable to store text to external storage $storeUrl" );
+ }
+ }
+ // All stores failed
+ if ( $error ) {
+ throw $error; // rethrow the last error
+ } else {
+ throw new MWException( "Unable to store text to external storage" );
+ }
+ }
+
+ /**
+ * @param string $data
+ * @param string $wiki
+ * @return string|bool The URL of the stored data item, or false on error
+ * @throws MWException
+ */
+ public static function insertToForeignDefault( $data, $wiki ) {
+ return self::insertToDefault( $data, [ 'wiki' => $wiki ] );
+ }
+}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff