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