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 accessible 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         /** @var FileBackendGroup */
  35         private $fbGroup;
  36
  37         /**
  38          * @see ExternalStoreMedium::__construct()
  39          * @param array $params Additional parameters include:
  40          *   - fbGroup: a FileBackendGroup instance
  41          */
  42         public function __construct( array $params ) {
  43                 parent::__construct( $params );
  44                 if ( !isset( $params['fbGroup'] ) || !( $params['fbGroup'] instanceof FileBackendGroup ) ) {
  45                         throw new InvalidArgumentException( "FileBackendGroup required in 'fbGroup' field." );
  46                 }
  47                 $this->fbGroup = $params['fbGroup'];
  48         }
  49
  50         /**
  51          * The URL returned is of the form of the form mwstore://backend/container/wiki/id
  52          *
  53          * @see ExternalStoreMedium::fetchFromURL()
  54          * @param string $url
  55          * @return bool
  56          */
  57         public function fetchFromURL( $url ) {
  58                 $be = $this->fbGroup->backendFromPath( $url );
  59                 if ( $be instanceof FileBackend ) {
  60                         // We don't need "latest" since objects are immutable and
  61                         // backends should at least have "read-after-create" consistency.
  62                         return $be->getFileContents( [ 'src' => $url ] );
  63                 }
  64
  65                 return false;
  66         }
  67
  68         /**
  69          * Fetch data from given external store URLs.
  70          * The URL returned is of the form of the form mwstore://backend/container/wiki/id
  71          *
  72          * @param array $urls An array of external store URLs
  73          * @return array A map from url to stored content. Failed results are not represented.
  74          */
  75         public function batchFetchFromURLs( array $urls ) {
  76                 $pathsByBackend = [];
  77                 foreach ( $urls as $url ) {
  78                         $be = $this->fbGroup->backendFromPath( $url );
  79                         if ( $be instanceof FileBackend ) {
  80                                 $pathsByBackend[$be->getName()][] = $url;
  81                         }
  82                 }
  83                 $blobs = [];
  84                 foreach ( $pathsByBackend as $backendName => $paths ) {
  85                         $be = $this->fbGroup->get( $backendName );
  86                         $blobs += $be->getFileContentsMulti( [ 'srcs' => $paths ] );
  87                 }
  88
  89                 return $blobs;
  90         }
  91
  92         /**
  93          * @inheritDoc
  94          */
  95         public function store( $backend, $data ) {
  96                 $be = $this->fbGroup->get( $backend );
  97                 // Get three random base 36 characters to act as shard directories
  98                 $rand = Wikimedia\base_convert( mt_rand( 0, 46655 ), 10, 36, 3 );
  99                 // Make sure ID is roughly lexicographically increasing for performance
 100                 $id = str_pad( UIDGenerator::newTimestampedUID128( 32 ), 26, '0', STR_PAD_LEFT );
 101                 // Segregate items by DB domain ID for the sake of bookkeeping
 102                 $domain = $this->isDbDomainExplicit
 103                         ? $this->dbDomain
 104                         // @FIXME: this does not include the schema for b/c but it ideally should
 105                         : WikiMap::getWikiIdFromDbDomain( $this->dbDomain );
 106                 $url = $be->getContainerStoragePath( 'data' ) . '/' . rawurlencode( $domain );
 107                 // Use directory/container sharding
 108                 $url .= ( $be instanceof FSFileBackend )
 109                         ? "/{$rand[0]}/{$rand[1]}/{$rand[2]}/{$id}" // keep directories small
 110                         : "/{$rand[0]}/{$rand[1]}/{$id}"; // container sharding is only 2-levels
 111
 112                 $be->prepare( [ 'dir' => dirname( $url ), 'noAccess' => 1, 'noListing' => 1 ] );
 113                 $status = $be->create( [ 'dst' => $url, 'content' => $data ] );
 114
 115                 if ( $status->isOK() ) {
 116                         return $url;
 117                 }
 118
 119                 throw new MWException( __METHOD__ . ": operation failed: $status" );
 120         }
 121
 122         public function isReadOnly( $backend ) {
 123                 if ( parent::isReadOnly( $backend ) ) {
 124                         return true;
 125                 }
 126
 127                 $be = $this->fbGroup->get( $backend );
 128
 129                 return $be ? $be->isReadOnly() : false;
 130         }
 131 }