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RevisionRenderer.php
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RevisionRenderer.php
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<?php
/**
* This file is part of MediaWiki.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
namespace MediaWiki\Revision;
use InvalidArgumentException;
use MediaWiki\Content\Renderer\ContentRenderer;
use MediaWiki\Html\Html;
use MediaWiki\Parser\ParserOptions;
use MediaWiki\Parser\ParserOutput;
use MediaWiki\Permissions\Authority;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use Wikimedia\Rdbms\ILoadBalancer;
/**
* The RevisionRenderer service provides access to rendered output for revisions.
* It does so by acting as a factory for RenderedRevision instances, which in turn
* provide lazy access to ParserOutput objects.
*
* One key responsibility of RevisionRenderer is implementing the layout used to combine
* the output of multiple slots.
*
* @since 1.32
*/
class RevisionRenderer {
/** @var LoggerInterface */
private $saveParseLogger;
/** @var ILoadBalancer */
private $loadBalancer;
/** @var SlotRoleRegistry */
private $roleRegistry;
/** @var ContentRenderer */
private $contentRenderer;
/** @var string|false */
private $dbDomain;
/**
* @param ILoadBalancer $loadBalancer
* @param SlotRoleRegistry $roleRegistry
* @param ContentRenderer $contentRenderer
* @param string|false $dbDomain DB domain of the relevant wiki or false for the current one
*/
public function __construct(
ILoadBalancer $loadBalancer,
SlotRoleRegistry $roleRegistry,
ContentRenderer $contentRenderer,
$dbDomain = false
) {
$this->loadBalancer = $loadBalancer;
$this->roleRegistry = $roleRegistry;
$this->contentRenderer = $contentRenderer;
$this->dbDomain = $dbDomain;
$this->saveParseLogger = new NullLogger();
}
/**
* @param LoggerInterface $saveParseLogger
*/
public function setLogger( LoggerInterface $saveParseLogger ) {
$this->saveParseLogger = $saveParseLogger;
}
// phpcs:disable Generic.Files.LineLength.TooLong
/**
* @param RevisionRecord $rev
* @param ParserOptions|null $options
* @param Authority|null $forPerformer User for privileged access. Default is unprivileged
* (public) access, unless the 'audience' hint is set to something else RevisionRecord::RAW.
* @param array{use-master?:bool,audience?:int,known-revision-output?:ParserOutput,causeAction?:?string,previous-output?:?ParserOutput} $hints
* Hints given as an associative array. Known keys:
* - 'use-master' Use primary DB when rendering for the parser cache during save.
* Default is to use a replica.
* - 'audience' the audience to use for content access. Default is
* RevisionRecord::FOR_PUBLIC if $forUser is not set, RevisionRecord::FOR_THIS_USER
* if $forUser is set. Can be set to RevisionRecord::RAW to disable audience checks.
* - 'known-revision-output' a combined ParserOutput for the revision, perhaps from
* some cache. the caller is responsible for ensuring that the ParserOutput indeed
* matched the $rev and $options. This mechanism is intended as a temporary stop-gap,
* for the time until caches have been changed to store RenderedRevision states instead
* of ParserOutput objects.
* - 'previous-output' A previously-rendered ParserOutput for this page. This
* can be used by Parsoid for selective updates.
* - 'causeAction' the reason for rendering. This should be informative, for used for
* logging and debugging.
*
* @return RenderedRevision|null The rendered revision, or null if the audience checks fails.
* @throws BadRevisionException
* @throws RevisionAccessException
*/
// phpcs:enable Generic.Files.LineLength.TooLong
public function getRenderedRevision(
RevisionRecord $rev,
?ParserOptions $options = null,
?Authority $forPerformer = null,
array $hints = []
) {
if ( $rev->getWikiId() !== $this->dbDomain ) {
throw new InvalidArgumentException( 'Mismatching wiki ID ' . $rev->getWikiId() );
}
$audience = $hints['audience']
?? ( $forPerformer ? RevisionRecord::FOR_THIS_USER : RevisionRecord::FOR_PUBLIC );
if ( !$rev->audienceCan( RevisionRecord::DELETED_TEXT, $audience, $forPerformer ) ) {
// Returning null here is awkward, but consistent with the signature of
// RevisionRecord::getContent().
return null;
}
if ( !$options ) {
$options = $forPerformer ?
ParserOptions::newFromUser( $forPerformer->getUser() ) :
ParserOptions::newFromAnon();
}
if ( isset( $hints['causeAction'] ) ) {
$options->setRenderReason( $hints['causeAction'] );
}
$usePrimary = $hints['use-master'] ?? false;
$dbIndex = $usePrimary
? DB_PRIMARY // use latest values
: DB_REPLICA; // T154554
$options->setSpeculativeRevIdCallback( function () use ( $dbIndex ) {
return $this->getSpeculativeRevId( $dbIndex );
} );
$options->setSpeculativePageIdCallback( function () use ( $dbIndex ) {
return $this->getSpeculativePageId( $dbIndex );
} );
if ( !$rev->getId() && $rev->getTimestamp() ) {
// This is an unsaved revision with an already determined timestamp.
// Make the "current" time used during parsing match that of the revision.
// Any REVISION* parser variables will match up if the revision is saved.
$options->setTimestamp( $rev->getTimestamp() );
}
$previousOutput = $hints['previous-output'] ?? null;
$renderedRevision = new RenderedRevision(
$rev,
$options,
$this->contentRenderer,
function ( RenderedRevision $rrev, array $hints ) use ( $options, $previousOutput ) {
$h = [ 'previous-output' => $previousOutput ] + $hints;
return $this->combineSlotOutput( $rrev, $options, $h );
},
$audience,
$forPerformer
);
$renderedRevision->setSaveParseLogger( $this->saveParseLogger );
if ( isset( $hints['known-revision-output'] ) ) {
$renderedRevision->setRevisionParserOutput( $hints['known-revision-output'] );
}
return $renderedRevision;
}
private function getSpeculativeRevId( $dbIndex ) {
// Use a separate primary DB connection in order to see the latest data, by avoiding
// stale data from REPEATABLE-READ snapshots.
$flags = ILoadBalancer::CONN_TRX_AUTOCOMMIT;
$db = $this->loadBalancer->getConnection( $dbIndex, [], $this->dbDomain, $flags );
return 1 + (int)$db->newSelectQueryBuilder()
->select( 'MAX(rev_id)' )
->from( 'revision' )
->caller( __METHOD__ )->fetchField();
}
private function getSpeculativePageId( $dbIndex ) {
// Use a separate primary DB connection in order to see the latest data, by avoiding
// stale data from REPEATABLE-READ snapshots.
$flags = ILoadBalancer::CONN_TRX_AUTOCOMMIT;
$db = $this->loadBalancer->getConnection( $dbIndex, [], $this->dbDomain, $flags );
return 1 + (int)$db->newSelectQueryBuilder()
->select( 'MAX(page_id)' )
->from( 'page' )
->caller( __METHOD__ )->fetchField();
}
/**
* This implements the layout for combining the output of multiple slots.
*
* @todo Use placement hints from SlotRoleHandlers instead of hard-coding the layout.
*
* @param RenderedRevision $rrev
* @param ParserOptions $options
* @param array $hints see RenderedRevision::getRevisionParserOutput()
*
* @return ParserOutput
* @throws SuppressedDataException
* @throws BadRevisionException
* @throws RevisionAccessException
*/
private function combineSlotOutput( RenderedRevision $rrev, ParserOptions $options, array $hints = [] ) {
$revision = $rrev->getRevision();
$slots = $revision->getSlots()->getSlots();
$withHtml = $hints['generate-html'] ?? true;
$previousOutputs = $this->splitSlotOutput( $rrev, $options, $hints['previous-output'] ?? null );
// short circuit if there is only the main slot
// T351026 hack: if use-parsoid is set, only return main slot output for now
// T351113 will remove this hack.
if ( array_keys( $slots ) === [ SlotRecord::MAIN ] || $options->getUseParsoid() ) {
$h = [ 'previous-output' => $previousOutputs[SlotRecord::MAIN] ] + $hints;
return $rrev->getSlotParserOutput( SlotRecord::MAIN, $h );
}
// move main slot to front
if ( isset( $slots[SlotRecord::MAIN] ) ) {
$slots = [ SlotRecord::MAIN => $slots[SlotRecord::MAIN] ] + $slots;
}
$combinedOutput = new ParserOutput( null );
$slotOutput = [];
$options = $rrev->getOptions();
$options->registerWatcher( [ $combinedOutput, 'recordOption' ] );
foreach ( $slots as $role => $slot ) {
$h = [ 'previous-output' => $previousOutputs[$role] ] + $hints;
$out = $rrev->getSlotParserOutput( $role, $h );
$slotOutput[$role] = $out;
// XXX: should the SlotRoleHandler be able to intervene here?
$combinedOutput->mergeInternalMetaDataFrom( $out );
$combinedOutput->mergeTrackingMetaDataFrom( $out );
}
if ( $withHtml ) {
$html = '';
$first = true;
/** @var ParserOutput $out */
foreach ( $slotOutput as $role => $out ) {
$roleHandler = $this->roleRegistry->getRoleHandler( $role );
// TODO: put more fancy layout logic here, see T200915.
$layout = $roleHandler->getOutputLayoutHints();
$display = $layout['display'] ?? 'section';
if ( $display === 'none' ) {
continue;
}
if ( $first ) {
// skip header for the first slot
$first = false;
} else {
// NOTE: this placeholder is hydrated by ParserOutput::getText().
$headText = Html::element( 'mw:slotheader', [], $role );
$html .= Html::rawElement( 'h1', [ 'class' => 'mw-slot-header' ], $headText );
}
// XXX: do we want to put a wrapper div around the output?
// Do we want to let $roleHandler do that?
$html .= $out->getRawText();
$combinedOutput->mergeHtmlMetaDataFrom( $out );
}
$combinedOutput->setRawText( $html );
}
$options->registerWatcher( null );
return $combinedOutput;
}
/**
* This reverses ::combineSlotOutput() in order to enable selective
* update of individual slots.
*
* @todo Currently this doesn't do much other than disable selective
* update if there is more than one slot. But in the case where
* slot combination is reversible, this should reverse it and attempt
* to reconstruct the original split ParserOutputs from the merged
* ParserOutput.
*
* @param RenderedRevision $rrev
* @param ParserOptions $options
* @param ?ParserOutput $previousOutput A combined ParserOutput for a
* previous parse, or null if none available.
* @return array<string,?ParserOutput> A mapping from role name to a
* previous ParserOutput for that slot in the previous parse
*/
private function splitSlotOutput( RenderedRevision $rrev, ParserOptions $options, ?ParserOutput $previousOutput ) {
// If there is no previous parse, then there is nothing to split.
$revision = $rrev->getRevision();
$revslots = $revision->getSlots();
if ( $previousOutput === null ) {
return array_fill_keys( $revslots->getSlotRoles(), null );
}
// short circuit if there is only the main slot
// T351026 hack: if use-parsoid is set, only return main slot output for now
// T351113 will remove this hack.
if ( $revslots->getSlotRoles() === [ SlotRecord::MAIN ] || $options->getUseParsoid() ) {
return [ SlotRecord::MAIN => $previousOutput ];
}
// @todo Currently slot combination is not reversible
return array_fill_keys( $revslots->getSlotRoles(), null );
}
}

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