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 SlotRoleRegistry */
  54         private $roleRegistery;
  55
  56         /** @var string|bool */
  57         private $wikiId;
  58
  59         /**
  60          * @param ILoadBalancer $loadBalancer
  61          * @param SlotRoleRegistry $roleRegistry
  62          * @param bool|string $wikiId
  63          */
  64         public function __construct(
  65                 ILoadBalancer $loadBalancer,
  66                 SlotRoleRegistry $roleRegistry,
  67                 $wikiId = false
  68         ) {
  69                 $this->loadBalancer = $loadBalancer;
  70                 $this->roleRegistery = $roleRegistry;
  71                 $this->wikiId = $wikiId;
  72
  73                 $this->saveParseLogger = new NullLogger();
  74         }
  75
  76         /**
  77          * @param LoggerInterface $saveParseLogger
  78          */
  79         public function setLogger( LoggerInterface $saveParseLogger ) {
  80                 $this->saveParseLogger = $saveParseLogger;
  81         }
  82
  83         /**
  84          * @param RevisionRecord $rev
  85          * @param ParserOptions|null $options
  86          * @param User|null $forUser User for privileged access. Default is unprivileged (public)
  87          *        access, unless the 'audience' hint is set to something else RevisionRecord::RAW.
  88          * @param array $hints Hints given as an associative array. Known keys:
  89          *      - 'use-master' Use master when rendering for the parser cache during save.
  90          *        Default is to use a replica.
  91          *      - 'audience' the audience to use for content access. Default is
  92          *        RevisionRecord::FOR_PUBLIC if $forUser is not set, RevisionRecord::FOR_THIS_USER
  93          *        if $forUser is set. Can be set to RevisionRecord::RAW to disable audience checks.
  94          *      - 'known-revision-output' a combined ParserOutput for the revision, perhaps from
  95          *        some cache. the caller is responsible for ensuring that the ParserOutput indeed
  96          *        matched the $rev and $options. This mechanism is intended as a temporary stop-gap,
  97          *        for the time until caches have been changed to store RenderedRevision states instead
  98          *        of ParserOutput objects.
  99          *
 100          * @return RenderedRevision|null The rendered revision, or null if the audience checks fails.
 101          */
 102         public function getRenderedRevision(
 103                 RevisionRecord $rev,
 104                 ParserOptions $options = null,
 105                 User $forUser = null,
 106                 array $hints = []
 107         ) {
 108                 if ( $rev->getWikiId() !== $this->wikiId ) {
 109                         throw new InvalidArgumentException( 'Mismatching wiki ID ' . $rev->getWikiId() );
 110                 }
 111
 112                 $audience = $hints['audience']
 113                         ?? ( $forUser ? RevisionRecord::FOR_THIS_USER : RevisionRecord::FOR_PUBLIC );
 114
 115                 if ( !$rev->audienceCan( RevisionRecord::DELETED_TEXT, $audience, $forUser ) ) {
 116                         // Returning null here is awkward, but consist with the signature of
 117                         // Revision::getContent() and RevisionRecord::getContent().
 118                         return null;
 119                 }
 120
 121                 if ( !$options ) {
 122                         $options = ParserOptions::newCanonical( $forUser ?: 'canonical' );
 123                 }
 124
 125                 $useMaster = $hints['use-master'] ?? false;
 126
 127                 $dbIndex = $useMaster
 128                         ? DB_MASTER // use latest values
 129                         : DB_REPLICA; // T154554
 130
 131                 $options->setSpeculativeRevIdCallback( function () use ( $dbIndex ) {
 132                         return $this->getSpeculativeRevId( $dbIndex );
 133                 } );
 134
 135                 $title = Title::newFromLinkTarget( $rev->getPageAsLinkTarget() );
 136
 137                 $renderedRevision = new RenderedRevision(
 138                         $title,
 139                         $rev,
 140                         $options,
 141                         function ( RenderedRevision $rrev, array $hints ) {
 142                                 return $this->combineSlotOutput( $rrev, $hints );
 143                         },
 144                         $audience,
 145                         $forUser
 146                 );
 147
 148                 $renderedRevision->setSaveParseLogger( $this->saveParseLogger );
 149
 150                 if ( isset( $hints['known-revision-output'] ) ) {
 151                         $renderedRevision->setRevisionParserOutput( $hints['known-revision-output'] );
 152                 }
 153
 154                 return $renderedRevision;
 155         }
 156
 157         private function getSpeculativeRevId( $dbIndex ) {
 158                 // Use a fresh master connection in order to see the latest data, by avoiding
 159                 // stale data from REPEATABLE-READ snapshots.
 160                 // HACK: But don't use a fresh connection in unit tests, since it would not have
 161                 // the fake tables. This should be handled by the LoadBalancer!
 162                 $flags = defined( 'MW_PHPUNIT_TEST' ) || $dbIndex === DB_REPLICA
 163                         ? 0 : ILoadBalancer::CONN_TRX_AUTOCOMMIT;
 164
 165                 $db = $this->loadBalancer->getConnectionRef( $dbIndex, [], $this->wikiId, $flags );
 166
 167                 return 1 + (int)$db->selectField(
 168                         'revision',
 169                         'MAX(rev_id)',
 170                         [],
 171                         __METHOD__
 172                 );
 173         }
 174
 175         /**
 176          * This implements the layout for combining the output of multiple slots.
 177          *
 178          * @todo Use placement hints from SlotRoleHandlers instead of hard-coding the layout.
 179          *
 180          * @param RenderedRevision $rrev
 181          * @param array $hints see RenderedRevision::getRevisionParserOutput()
 182          *
 183          * @return ParserOutput
 184          */
 185         private function combineSlotOutput( RenderedRevision $rrev, array $hints = [] ) {
 186                 $revision = $rrev->getRevision();
 187                 $slots = $revision->getSlots()->getSlots();
 188
 189                 $withHtml = $hints['generate-html'] ?? true;
 190
 191                 // short circuit if there is only the main slot
 192                 if ( array_keys( $slots ) === [ SlotRecord::MAIN ] ) {
 193                         return $rrev->getSlotParserOutput( SlotRecord::MAIN );
 194                 }
 195
 196                 // move main slot to front
 197                 if ( isset( $slots[SlotRecord::MAIN] ) ) {
 198                         $slots = [ SlotRecord::MAIN => $slots[SlotRecord::MAIN] ] + $slots;
 199                 }
 200
 201                 $combinedOutput = new ParserOutput( null );
 202                 $slotOutput = [];
 203
 204                 $options = $rrev->getOptions();
 205                 $options->registerWatcher( [ $combinedOutput, 'recordOption' ] );
 206
 207                 foreach ( $slots as $role => $slot ) {
 208                         $out = $rrev->getSlotParserOutput( $role, $hints );
 209                         $slotOutput[$role] = $out;
 210
 211                         // XXX: should the SlotRoleHandler be able to intervene here?
 212                         $combinedOutput->mergeInternalMetaDataFrom( $out, $role );
 213                         $combinedOutput->mergeTrackingMetaDataFrom( $out );
 214                 }
 215
 216                 if ( $withHtml ) {
 217                         $html = '';
 218                         $first = true;
 219                         /** @var ParserOutput $out */
 220                         foreach ( $slotOutput as $role => $out ) {
 221                                 $roleHandler = $this->roleRegistery->getRoleHandler( $role );
 222
 223                                 // TODO: put more fancy layout logic here, see T200915.
 224                                 $layout = $roleHandler->getOutputLayoutHints();
 225                                 $display = $layout['display'] ?? 'section';
 226
 227                                 if ( $display === 'none' ) {
 228                                         continue;
 229                                 }
 230
 231                                 if ( $first ) {
 232                                         // skip header for the first slot
 233                                         $first = false;
 234                                 } else {
 235                                         // NOTE: this placeholder is hydrated by ParserOutput::getText().
 236                                         $headText = Html::element( 'mw:slotheader', [], $role );
 237                                         $html .= Html::rawElement( 'h1', [ 'class' => 'mw-slot-header' ], $headText );
 238                                 }
 239
 240                                 // XXX: do we want to put a wrapper div around the output?
 241                                 // Do we want to let $roleHandler do that?
 242                                 $html .= $out->getRawText();
 243                                 $combinedOutput->mergeHtmlMetaDataFrom( $out );
 244                         }
 245
 246                         $combinedOutput->setText( $html );
 247                 }
 248
 249                 $options->registerWatcher( null );
 250                 return $combinedOutput;
 251         }
 252
 253 }