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 LoggerInterface $saveParseLogger
  69          */
  70         public function setLogger( LoggerInterface $saveParseLogger ) {
  71                 $this->saveParseLogger = $saveParseLogger;
  72         }
  73
  74         /**
  75          * @param RevisionRecord $rev
  76          * @param ParserOptions|null $options
  77          * @param User|null $forUser User for privileged access. Default is unprivileged (public)
  78          *        access, unless the 'audience' hint is set to something else RevisionRecord::RAW.
  79          * @param array $hints Hints given as an associative array. Known keys:
  80          *      - 'use-master' Use master when rendering for the parser cache during save.
  81          *        Default is to use a replica.
  82          *      - 'audience' the audience to use for content access. Default is
  83          *        RevisionRecord::FOR_PUBLIC if $forUser is not set, RevisionRecord::FOR_THIS_USER
  84          *        if $forUser is set. Can be set to RevisionRecord::RAW to disable audience checks.
  85          *      - 'known-revision-output' a combined ParserOutput for the revision, perhaps from
  86          *        some cache. the caller is responsible for ensuring that the ParserOutput indeed
  87          *        matched the $rev and $options. This mechanism is intended as a temporary stop-gap,
  88          *        for the time until caches have been changed to store RenderedRevision states instead
  89          *        of ParserOutput objects.
  90          *
  91          * @return RenderedRevision|null The rendered revision, or null if the audience checks fails.
  92          */
  93         public function getRenderedRevision(
  94                 RevisionRecord $rev,
  95                 ParserOptions $options = null,
  96                 User $forUser = null,
  97                 array $hints = []
  98         ) {
  99                 if ( $rev->getWikiId() !== $this->wikiId ) {
 100                         throw new InvalidArgumentException( 'Mismatching wiki ID ' . $rev->getWikiId() );
 101                 }
 102
 103                 $audience = $hints['audience']
 104                         ?? ( $forUser ? RevisionRecord::FOR_THIS_USER : RevisionRecord::FOR_PUBLIC );
 105
 106                 if ( !$rev->audienceCan( RevisionRecord::DELETED_TEXT, $audience, $forUser ) ) {
 107                         // Returning null here is awkward, but consist with the signature of
 108                         // Revision::getContent() and RevisionRecord::getContent().
 109                         return null;
 110                 }
 111
 112                 if ( !$options ) {
 113                         $options = ParserOptions::newCanonical( $forUser ?: 'canonical' );
 114                 }
 115
 116                 $useMaster = $hints['use-master'] ?? false;
 117
 118                 $dbIndex = $useMaster
 119                         ? DB_MASTER // use latest values
 120                         : DB_REPLICA; // T154554
 121
 122                 $options->setSpeculativeRevIdCallback( function () use ( $dbIndex ) {
 123                         return $this->getSpeculativeRevId( $dbIndex );
 124                 } );
 125
 126                 $title = Title::newFromLinkTarget( $rev->getPageAsLinkTarget() );
 127
 128                 $renderedRevision = new RenderedRevision(
 129                         $title,
 130                         $rev,
 131                         $options,
 132                         function ( RenderedRevision $rrev, array $hints ) {
 133                                 return $this->combineSlotOutput( $rrev, $hints );
 134                         },
 135                         $audience,
 136                         $forUser
 137                 );
 138
 139                 $renderedRevision->setSaveParseLogger( $this->saveParseLogger );
 140
 141                 if ( isset( $hints['known-revision-output'] ) ) {
 142                         $renderedRevision->setRevisionParserOutput( $hints['known-revision-output'] );
 143                 }
 144
 145                 return $renderedRevision;
 146         }
 147
 148         private function getSpeculativeRevId( $dbIndex ) {
 149                 // Use a fresh master connection in order to see the latest data, by avoiding
 150                 // stale data from REPEATABLE-READ snapshots.
 151                 // HACK: But don't use a fresh connection in unit tests, since it would not have
 152                 // the fake tables. This should be handled by the LoadBalancer!
 153                 $flags = defined( 'MW_PHPUNIT_TEST' ) || $dbIndex === DB_REPLICA
 154                         ? 0 : ILoadBalancer::CONN_TRX_AUTOCOMMIT;
 155
 156                 $db = $this->loadBalancer->getConnectionRef( $dbIndex, [], $this->wikiId, $flags );
 157
 158                 return 1 + (int)$db->selectField(
 159                         'revision',
 160                         'MAX(rev_id)',
 161                         [],
 162                         __METHOD__
 163                 );
 164         }
 165
 166         /**
 167          * This implements the layout for combining the output of multiple slots.
 168          *
 169          * @todo Use placement hints from SlotRoleHandlers instead of hard-coding the layout.
 170          *
 171          * @param RenderedRevision $rrev
 172          * @param array $hints see RenderedRevision::getRevisionParserOutput()
 173          *
 174          * @return ParserOutput
 175          */
 176         private function combineSlotOutput( RenderedRevision $rrev, array $hints = [] ) {
 177                 $revision = $rrev->getRevision();
 178                 $slots = $revision->getSlots()->getSlots();
 179
 180                 $withHtml = $hints['generate-html'] ?? true;
 181
 182                 // short circuit if there is only the main slot
 183                 if ( array_keys( $slots ) === [ SlotRecord::MAIN ] ) {
 184                         return $rrev->getSlotParserOutput( SlotRecord::MAIN );
 185                 }
 186
 187                 // TODO: put fancy layout logic here, see T200915.
 188
 189                 // move main slot to front
 190                 if ( isset( $slots[SlotRecord::MAIN] ) ) {
 191                         $slots = [ SlotRecord::MAIN => $slots[SlotRecord::MAIN] ] + $slots;
 192                 }
 193
 194                 $combinedOutput = new ParserOutput( null );
 195                 $slotOutput = [];
 196
 197                 $options = $rrev->getOptions();
 198                 $options->registerWatcher( [ $combinedOutput, 'recordOption' ] );
 199
 200                 foreach ( $slots as $role => $slot ) {
 201                         $out = $rrev->getSlotParserOutput( $role, $hints );
 202                         $slotOutput[$role] = $out;
 203
 204                         $combinedOutput->mergeInternalMetaDataFrom( $out, $role );
 205                         $combinedOutput->mergeTrackingMetaDataFrom( $out );
 206                 }
 207
 208                 if ( $withHtml ) {
 209                         $html = '';
 210                         $first = true;
 211                         /** @var ParserOutput $out */
 212                         foreach ( $slotOutput as $role => $out ) {
 213                                 if ( $first ) {
 214                                         // skip header for the first slot
 215                                         $first = false;
 216                                 } else {
 217                                         // NOTE: this placeholder is hydrated by ParserOutput::getText().
 218                                         $headText = Html::element( 'mw:slotheader', [], $role );
 219                                         $html .= Html::rawElement( 'h1', [ 'class' => 'mw-slot-header' ], $headText );
 220                                 }
 221
 222                                 $html .= $out->getRawText();
 223                                 $combinedOutput->mergeHtmlMetaDataFrom( $out );
 224                         }
 225
 226                         $combinedOutput->setText( $html );
 227                 }
 228
 229                 $options->registerWatcher( null );
 230                 return $combinedOutput;
 231         }
 232
 233 }