includes/externalstore/ExternalStoreMwstore.php

   1 <?php
   2 /**
   3  * External storage in a file backend.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * File backend accessable external objects.
  25  *
  26  * In this system, each store "location" maps to the name of a file backend.
  27  * The file backends must be defined in $wgFileBackends and must be global
  28  * and fully qualified with a global "wikiId" prefix in the configuration.
  29  *
  30  * @ingroup ExternalStorage
  31  * @since 1.21
  32  */
  33 class ExternalStoreMwstore extends ExternalStoreMedium {
  34         /**
  35          * The URL returned is of the form of the form mwstore://backend/container/wiki/id
  36          *
  37          * @see ExternalStoreMedium::fetchFromURL()
  38          */
  39         public function fetchFromURL( $url ) {
  40                 $be = FileBackendGroup::singleton()->backendFromPath( $url );
  41                 if ( $be instanceof FileBackend ) {
  42                         // We don't need "latest" since objects are immutable and
  43                         // backends should at least have "read-after-create" consistency.
  44                         return $be->getFileContents( array( 'src' => $url ) );
  45                 }
  46
  47                 return false;
  48         }
  49
  50         /**
  51          * Fetch data from given external store URLs.
  52          * The URL returned is of the form of the form mwstore://backend/container/wiki/id
  53          *
  54          * @param array $urls An array of external store URLs
  55          * @return array A map from url to stored content. Failed results are not represented.
  56          */
  57         public function batchFetchFromURLs( array $urls ) {
  58                 $pathsByBackend = array();
  59                 foreach ( $urls as $url ) {
  60                         $be = FileBackendGroup::singleton()->backendFromPath( $url );
  61                         if ( $be instanceof FileBackend ) {
  62                                 $pathsByBackend[$be->getName()][] = $url;
  63                         }
  64                 }
  65                 $blobs = array();
  66                 foreach ( $pathsByBackend as $backendName => $paths ) {
  67                         $be = FileBackendGroup::singleton()->get( $backendName );
  68                         $blobs = $blobs + $be->getFileContentsMulti( array( 'srcs' => $paths ) );
  69                 }
  70
  71                 return $blobs;
  72         }
  73
  74         /**
  75          * @see ExternalStoreMedium::store()
  76          */
  77         public function store( $backend, $data ) {
  78                 $be = FileBackendGroup::singleton()->get( $backend );
  79                 if ( $be instanceof FileBackend ) {
  80                         // Get three random base 36 characters to act as shard directories
  81                         $rand = Wikimedia\base_convert( mt_rand( 0, 46655 ), 10, 36, 3 );
  82                         // Make sure ID is roughly lexicographically increasing for performance
  83                         $id = str_pad( UIDGenerator::newTimestampedUID128( 32 ), 26, '0', STR_PAD_LEFT );
  84                         // Segregate items by wiki ID for the sake of bookkeeping
  85                         $wiki = isset( $this->params['wiki'] ) ? $this->params['wiki'] : wfWikiID();
  86
  87                         $url = $be->getContainerStoragePath( 'data' ) . '/' . rawurlencode( $wiki );
  88                         $url .= ( $be instanceof FSFileBackend )
  89                                 ? "/{$rand[0]}/{$rand[1]}/{$rand[2]}/{$id}" // keep directories small
  90                                 : "/{$rand[0]}/{$rand[1]}/{$id}"; // container sharding is only 2-levels
  91
  92                         $be->prepare( array( 'dir' => dirname( $url ), 'noAccess' => 1, 'noListing' => 1 ) );
  93                         if ( $be->create( array( 'dst' => $url, 'content' => $data ) )->isOK() ) {
  94                                 return $url;
  95                         }
  96                 }
  97
  98                 return false;
  99         }
 100 }