includes/Revision/RevisionRenderer.php

   1 <?php
   2 /**
   3  * This file is part of MediaWiki.
   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 namespace MediaWiki\Revision;
  24
  25 use Html;
  26 use InvalidArgumentException;
  27 use MediaWiki\Storage\RevisionRecord;
  28 use ParserOptions;
  29 use ParserOutput;
  30 use Psr\Log\LoggerInterface;
  31 use Psr\Log\NullLogger;
  32 use Title;
  33 use User;
  34 use Wikimedia\Rdbms\ILoadBalancer;
  35
  36 /**
  37  * The RevisionRenderer service provides access to rendered output for revisions.
  38  * It does so be acting as a factory for RenderedRevision instances, which in turn
  39  * provide lazy access to ParserOutput objects.
  40  *
  41  * One key responsibility of RevisionRenderer is implementing the layout used to combine
  42  * the output of multiple slots.
  43  *
  44  * @since 1.32
  45  */
  46 class RevisionRenderer {
  47
  48         /** @var LoggerInterface */
  49         private $saveParseLogger;
  50
  51         /** @var ILoadBalancer */
  52         private $loadBalancer;
  53
  54         /** @var string|bool */
  55         private $wikiId;
  56
  57         /**
  58          * @param ILoadBalancer $loadBalancer
  59          * @param bool|string $wikiId
  60          */
  61         public function __construct( ILoadBalancer $loadBalancer, $wikiId = false ) {
  62                 $this->loadBalancer = $loadBalancer;
  63                 $this->wikiId = $wikiId;
  64
  65                 $this->saveParseLogger = new NullLogger();
  66         }
  67
  68         /**
  69          * @param RevisionRecord $rev
  70          * @param ParserOptions|null $options
  71          * @param User|null $forUser User for privileged access. Default is unprivileged (public)
  72          *        access, unless the 'audience' hint is set to something else RevisionRecord::RAW.
  73          * @param array $hints Hints given as an associative array. Known keys:
  74          *      - 'use-master' Use master when rendering for the parser cache during save.
  75          *        Default is to use a replica.
  76          *      - 'audience' the audience to use for content access. Default is
  77          *        RevisionRecord::FOR_PUBLIC if $forUser is not set, RevisionRecord::FOR_THIS_USER
  78          *        if $forUser is set. Can be set to RevisionRecord::RAW to disable audience checks.
  79          *
  80          * @return RenderedRevision|null The rendered revision, or null if the audience checks fails.
  81          */
  82         public function getRenderedRevision(
  83                 RevisionRecord $rev,
  84                 ParserOptions $options = null,
  85                 User $forUser = null,
  86                 array $hints = []
  87         ) {
  88                 if ( $rev->getWikiId() !== $this->wikiId ) {
  89                         throw new InvalidArgumentException( 'Mismatching wiki ID ' . $rev->getWikiId() );
  90                 }
  91
  92                 $audience = $hints['audience']
  93                         ?? ( $forUser ? RevisionRecord::FOR_THIS_USER : RevisionRecord::FOR_PUBLIC );
  94
  95                 if ( !$rev->audienceCan( RevisionRecord::DELETED_TEXT, $audience, $forUser ) ) {
  96                         // Returning null here is awkward, but consist with the signature of
  97                         // Revision::getContent() and RevisionRecord::getContent().
  98                         return null;
  99                 }
 100
 101                 if ( !$options ) {
 102                         $options = ParserOptions::newCanonical( $forUser ?: 'canonical' );
 103                 }
 104
 105                 $useMaster = $hints['use-master'] ?? false;
 106
 107                 $dbIndex = $useMaster
 108                         ? DB_MASTER // use latest values
 109                         : DB_REPLICA; // T154554
 110
 111                 $options->setSpeculativeRevIdCallback( function () use ( $dbIndex ) {
 112                         return $this->getSpeculativeRevId( $dbIndex );
 113                 } );
 114
 115                 $title = Title::newFromLinkTarget( $rev->getPageAsLinkTarget() );
 116
 117                 $renderedRevision = new RenderedRevision(
 118                         $title,
 119                         $rev,
 120                         $options,
 121                         function ( RenderedRevision $rrev, array $hints ) {
 122                                 return $this->combineSlotOutput( $rrev, $hints );
 123                         },
 124                         $audience,
 125                         $forUser
 126                 );
 127
 128                 $renderedRevision->setSaveParseLogger( $this->saveParseLogger );
 129
 130                 return $renderedRevision;
 131         }
 132
 133         private function getSpeculativeRevId( $dbIndex ) {
 134                 // Use a fresh master connection in order to see the latest data, by avoiding
 135                 // stale data from REPEATABLE-READ snapshots.
 136                 // HACK: But don't use a fresh connection in unit tests, since it would not have
 137                 // the fake tables. This should be handled by the LoadBalancer!
 138                 $flags = defined( 'MW_PHPUNIT_TEST' ) || $dbIndex === DB_REPLICA
 139                         ? 0 : ILoadBalancer::CONN_TRX_AUTOCOMMIT;
 140
 141                 $db = $this->loadBalancer->getConnectionRef( $dbIndex, [], $this->wikiId, $flags );
 142
 143                 return 1 + (int)$db->selectField(
 144                         'revision',
 145                         'MAX(rev_id)',
 146                         [],
 147                         __METHOD__
 148                 );
 149         }
 150
 151         /**
 152          * This implements the layout for combining the output of multiple slots.
 153          *
 154          * @todo Use placement hints from SlotRoleHandlers instead of hard-coding the layout.
 155          *
 156          * @param RenderedRevision $rrev
 157          * @param array $hints see RenderedRevision::getRevisionParserOutput()
 158          *
 159          * @return ParserOutput
 160          */
 161         private function combineSlotOutput( RenderedRevision $rrev, array $hints = [] ) {
 162                 $revision = $rrev->getRevision();
 163                 $slots = $revision->getSlots()->getSlots();
 164
 165                 $withHtml = $hints['generate-html'] ?? true;
 166
 167                 // short circuit if there is only the main slot
 168                 if ( array_keys( $slots ) === [ 'main' ] ) {
 169                         return $rrev->getSlotParserOutput( 'main' );
 170                 }
 171
 172                 // TODO: put fancy layout logic here, see T200915.
 173
 174                 // move main slot to front
 175                 if ( isset( $slots['main'] ) ) {
 176                         $slots = [ 'main' => $slots['main'] ] + $slots;
 177                 }
 178
 179                 $combinedOutput = new ParserOutput( null );
 180                 $slotOutput = [];
 181
 182                 $options = $rrev->getOptions();
 183                 $options->registerWatcher( [ $combinedOutput, 'recordOption' ] );
 184
 185                 foreach ( $slots as $role => $slot ) {
 186                         $out = $rrev->getSlotParserOutput( $role, $hints );
 187                         $slotOutput[$role] = $out;
 188
 189                         $combinedOutput->mergeInternalMetaDataFrom( $out, $role );
 190                         $combinedOutput->mergeTrackingMetaDataFrom( $out );
 191                 }
 192
 193                 if ( $withHtml ) {
 194                         $html = '';
 195                         $first = true;
 196                         /** @var ParserOutput $out */
 197                         foreach ( $slotOutput as $role => $out ) {
 198                                 if ( $first ) {
 199                                         // skip header for the first slot
 200                                         $first = false;
 201                                 } else {
 202                                         // NOTE: this placeholder is hydrated by ParserOutput::getText().
 203                                         $headText = Html::element( 'mw:slotheader', [], $role );
 204                                         $html .= Html::rawElement( 'h1', [ 'class' => 'mw-slot-header' ], $headText );
 205                                 }
 206
 207                                 $html .= $out->getRawText();
 208                                 $combinedOutput->mergeHtmlMetaDataFrom( $out );
 209                         }
 210
 211                         $combinedOutput->setText( $html );
 212                 }
 213
 214                 $options->registerWatcher( null );
 215                 return $combinedOutput;
 216         }
 217
 218 }