MediaWiki.php

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<?php
use MediaWiki\Logger\LoggerFactory;

class MediaWiki {
    private $context;

    private $config;

    private $action;

    public function __construct( IContextSource $context = null ) {
        if ( !$context ) {
            $context = RequestContext::getMain();
        }

        $this->context = $context;
        $this->config = $context->getConfig();
    }

    private function parseTitle() {
        global $wgContLang;

        $request = $this->context->getRequest();
        $curid = $request->getInt( 'curid' );
        $title = $request->getVal( 'title' );
        $action = $request->getVal( 'action' );

        if ( $request->getCheck( 'search' ) ) {
            // Compatibility with old search URLs which didn't use Special:Search
            // Just check for presence here, so blank requests still
            // show the search page when using ugly URLs (bug 8054).
            $ret = SpecialPage::getTitleFor( 'Search' );
        } elseif ( $curid ) {
            // URLs like this are generated by RC, because rc_title isn't always accurate
            $ret = Title::newFromID( $curid );
        } else {
            $ret = Title::newFromURL( $title );
            // Alias NS_MEDIA page URLs to NS_FILE...we only use NS_MEDIA
            // in wikitext links to tell Parser to make a direct file link
            if ( !is_null( $ret ) && $ret->getNamespace() == NS_MEDIA ) {
                $ret = Title::makeTitle( NS_FILE, $ret->getDBkey() );
            }
            // Check variant links so that interwiki links don't have to worry
            // about the possible different language variants
            if ( count( $wgContLang->getVariants() ) > 1
                && !is_null( $ret ) && $ret->getArticleID() == 0
            ) {
                $wgContLang->findVariantLink( $title, $ret );
            }
        }

        // If title is not provided, always allow oldid and diff to set the title.
        // If title is provided, allow oldid and diff to override the title, unless
        // we are talking about a special page which might use these parameters for
        // other purposes.
        if ( $ret === null || !$ret->isSpecialPage() ) {
            // We can have urls with just ?diff=,?oldid= or even just ?diff=
            $oldid = $request->getInt( 'oldid' );
            $oldid = $oldid ? $oldid : $request->getInt( 'diff' );
            // Allow oldid to override a changed or missing title
            if ( $oldid ) {
                $rev = Revision::newFromId( $oldid );
                $ret = $rev ? $rev->getTitle() : $ret;
            }
        }

        // Use the main page as default title if nothing else has been provided
        if ( $ret === null
            && strval( $title ) === ''
            && !$request->getCheck( 'curid' )
            && $action !== 'delete'
        ) {
            $ret = Title::newMainPage();
        }

        if ( $ret === null || ( $ret->getDBkey() == '' && !$ret->isExternal() ) ) {
            // If we get here, we definitely don't have a valid title; throw an exception.
            // Try to get detailed invalid title exception first, fall back to MalformedTitleException.
            Title::newFromTextThrow( $title );
            throw new MalformedTitleException( 'badtitletext', $title );
        }

        return $ret;
    }

    public function getTitle() {
        if ( !$this->context->hasTitle() ) {
            try {
                $this->context->setTitle( $this->parseTitle() );
            } catch ( MalformedTitleException $ex ) {
                $this->context->setTitle( SpecialPage::getTitleFor( 'Badtitle' ) );
            }
        }
        return $this->context->getTitle();
    }

    public function getAction() {
        if ( $this->action === null ) {
            $this->action = Action::getActionName( $this->context );
        }

        return $this->action;
    }

    private function performRequest() {
        global $wgTitle;

        $request = $this->context->getRequest();
        $requestTitle = $title = $this->context->getTitle();
        $output = $this->context->getOutput();
        $user = $this->context->getUser();

        if ( $request->getVal( 'printable' ) === 'yes' ) {
            $output->setPrintable();
        }

        $unused = null; // To pass it by reference
        Hooks::run( 'BeforeInitialize', [ &$title, &$unused, &$output, &$user, $request, $this ] );

        // Invalid titles. Bug 21776: The interwikis must redirect even if the page name is empty.
        if ( is_null( $title ) || ( $title->getDBkey() == '' && !$title->isExternal() )
            || $title->isSpecial( 'Badtitle' )
        ) {
            $this->context->setTitle( SpecialPage::getTitleFor( 'Badtitle' ) );
            try {
                $this->parseTitle();
            } catch ( MalformedTitleException $ex ) {
                throw new BadTitleError( $ex );
            }
            throw new BadTitleError();
        }

        // Check user's permissions to read this page.
        // We have to check here to catch special pages etc.
        // We will check again in Article::view().
        $permErrors = $title->isSpecial( 'RunJobs' )
            ? [] // relies on HMAC key signature alone
            : $title->getUserPermissionsErrors( 'read', $user );
        if ( count( $permErrors ) ) {
            // Bug 32276: allowing the skin to generate output with $wgTitle or
            // $this->context->title set to the input title would allow anonymous users to
            // determine whether a page exists, potentially leaking private data. In fact, the
            // curid and oldid request  parameters would allow page titles to be enumerated even
            // when they are not guessable. So we reset the title to Special:Badtitle before the
            // permissions error is displayed.

            // The skin mostly uses $this->context->getTitle() these days, but some extensions
            // still use $wgTitle.
            $badTitle = SpecialPage::getTitleFor( 'Badtitle' );
            $this->context->setTitle( $badTitle );
            $wgTitle = $badTitle;

            throw new PermissionsError( 'read', $permErrors );
        }

        // Interwiki redirects
        if ( $title->isExternal() ) {
            $rdfrom = $request->getVal( 'rdfrom' );
            if ( $rdfrom ) {
                $url = $title->getFullURL( [ 'rdfrom' => $rdfrom ] );
            } else {
                $query = $request->getValues();
                unset( $query['title'] );
                $url = $title->getFullURL( $query );
            }
            // Check for a redirect loop
            if ( !preg_match( '/^' . preg_quote( $this->config->get( 'Server' ), '/' ) . '/', $url )
                && $title->isLocal()
            ) {
                // 301 so google et al report the target as the actual url.
                $output->redirect( $url, 301 );
            } else {
                $this->context->setTitle( SpecialPage::getTitleFor( 'Badtitle' ) );
                try {
                    $this->parseTitle();
                } catch ( MalformedTitleException $ex ) {
                    throw new BadTitleError( $ex );
                }
                throw new BadTitleError();
            }
        // Handle any other redirects.
        // Redirect loops, titleless URL, $wgUsePathInfo URLs, and URLs with a variant
        } elseif ( !$this->tryNormaliseRedirect( $title ) ) {
            // Prevent information leak via Special:MyPage et al (T109724)
            if ( $title->isSpecialPage() ) {
                $specialPage = SpecialPageFactory::getPage( $title->getDBkey() );
                if ( $specialPage instanceof RedirectSpecialPage ) {
                    $specialPage->setContext( $this->context );
                    if ( $this->config->get( 'HideIdentifiableRedirects' )
                        && $specialPage->personallyIdentifiableTarget()
                    ) {
                        list( , $subpage ) = SpecialPageFactory::resolveAlias( $title->getDBkey() );
                        $target = $specialPage->getRedirect( $subpage );
                        // target can also be true. We let that case fall through to normal processing.
                        if ( $target instanceof Title ) {
                            $query = $specialPage->getRedirectQuery() ?: [];
                            $request = new DerivativeRequest( $this->context->getRequest(), $query );
                            $request->setRequestURL( $this->context->getRequest()->getRequestURL() );
                            $this->context->setRequest( $request );
                            // Do not varnish cache these. May vary even for anons
                            $this->context->getOutput()->lowerCdnMaxage( 0 );
                            $this->context->setTitle( $target );
                            $wgTitle = $target;
                            // Reset action type cache. (Special pages have only view)
                            $this->action = null;
                            $title = $target;
                            $output->addJsConfigVars( [
                                'wgInternalRedirectTargetUrl' => $target->getFullURL( $query ),
                            ] );
                            $output->addModules( 'mediawiki.action.view.redirect' );
                        }
                    }
                }
            }

            // Special pages ($title may have changed since if statement above)
            if ( NS_SPECIAL == $title->getNamespace() ) {
                // Actions that need to be made when we have a special pages
                SpecialPageFactory::executePath( $title, $this->context );
            } else {
                // ...otherwise treat it as an article view. The article
                // may still be a wikipage redirect to another article or URL.
                $article = $this->initializeArticle();
                if ( is_object( $article ) ) {
                    $this->performAction( $article, $requestTitle );
                } elseif ( is_string( $article ) ) {
                    $output->redirect( $article );
                } else {
                    throw new MWException( "Shouldn't happen: MediaWiki::initializeArticle()"
                        . " returned neither an object nor a URL" );
                }
            }
        }
    }

    private function tryNormaliseRedirect( Title $title ) {
        $request = $this->context->getRequest();
        $output = $this->context->getOutput();

        if ( $request->getVal( 'action', 'view' ) != 'view'
            || $request->wasPosted()
            || ( $request->getVal( 'title' ) !== null
                && $title->getPrefixedDBkey() == $request->getVal( 'title' ) )
            || count( $request->getValueNames( [ 'action', 'title' ] ) )
            || !Hooks::run( 'TestCanonicalRedirect', [ $request, $title, $output ] )
        ) {
            return false;
        }

        if ( $title->isSpecialPage() ) {
            list( $name, $subpage ) = SpecialPageFactory::resolveAlias( $title->getDBkey() );
            if ( $name ) {
                $title = SpecialPage::getTitleFor( $name, $subpage );
            }
        }
        // Redirect to canonical url, make it a 301 to allow caching
        $targetUrl = wfExpandUrl( $title->getFullURL(), PROTO_CURRENT );
        if ( $targetUrl == $request->getFullRequestURL() ) {
            $message = "Redirect loop detected!\n\n" .
                "This means the wiki got confused about what page was " .
                "requested; this sometimes happens when moving a wiki " .
                "to a new server or changing the server configuration.\n\n";

            if ( $this->config->get( 'UsePathInfo' ) ) {
                $message .= "The wiki is trying to interpret the page " .
                    "title from the URL path portion (PATH_INFO), which " .
                    "sometimes fails depending on the web server. Try " .
                    "setting \"\$wgUsePathInfo = false;\" in your " .
                    "LocalSettings.php, or check that \$wgArticlePath " .
                    "is correct.";
            } else {
                $message .= "Your web server was detected as possibly not " .
                    "supporting URL path components (PATH_INFO) correctly; " .
                    "check your LocalSettings.php for a customized " .
                    "\$wgArticlePath setting and/or toggle \$wgUsePathInfo " .
                    "to true.";
            }
            throw new HttpError( 500, $message );
        }
        $output->setSquidMaxage( 1200 );
        $output->redirect( $targetUrl, '301' );
        return true;
    }

    private function initializeArticle() {
        $title = $this->context->getTitle();
        if ( $this->context->canUseWikiPage() ) {
            // Try to use request context wiki page, as there
            // is already data from db saved in per process
            // cache there from this->getAction() call.
            $page = $this->context->getWikiPage();
        } else {
            // This case should not happen, but just in case.
            // @TODO: remove this or use an exception
            $page = WikiPage::factory( $title );
            $this->context->setWikiPage( $page );
            wfWarn( "RequestContext::canUseWikiPage() returned false" );
        }

        // Make GUI wrapper for the WikiPage
        $article = Article::newFromWikiPage( $page, $this->context );

        // Skip some unnecessary code if the content model doesn't support redirects
        if ( !ContentHandler::getForTitle( $title )->supportsRedirects() ) {
            return $article;
        }

        $request = $this->context->getRequest();

        // Namespace might change when using redirects
        // Check for redirects ...
        $action = $request->getVal( 'action', 'view' );
        $file = ( $page instanceof WikiFilePage ) ? $page->getFile() : null;
        if ( ( $action == 'view' || $action == 'render' ) // ... for actions that show content
            && !$request->getVal( 'oldid' ) // ... and are not old revisions
            && !$request->getVal( 'diff' ) // ... and not when showing diff
            && $request->getVal( 'redirect' ) != 'no' // ... unless explicitly told not to
            // ... and the article is not a non-redirect image page with associated file
            && !( is_object( $file ) && $file->exists() && !$file->getRedirected() )
        ) {
            // Give extensions a change to ignore/handle redirects as needed
            $ignoreRedirect = $target = false;

            Hooks::run( 'InitializeArticleMaybeRedirect',
                [ &$title, &$request, &$ignoreRedirect, &$target, &$article ] );
            $page = $article->getPage(); // reflect any hook changes

            // Follow redirects only for... redirects.
            // If $target is set, then a hook wanted to redirect.
            if ( !$ignoreRedirect && ( $target || $page->isRedirect() ) ) {
                // Is the target already set by an extension?
                $target = $target ? $target : $page->followRedirect();
                if ( is_string( $target ) ) {
                    if ( !$this->config->get( 'DisableHardRedirects' ) ) {
                        // we'll need to redirect
                        return $target;
                    }
                }
                if ( is_object( $target ) ) {
                    // Rewrite environment to redirected article
                    $rpage = WikiPage::factory( $target );
                    $rpage->loadPageData();
                    if ( $rpage->exists() || ( is_object( $file ) && !$file->isLocal() ) ) {
                        $rarticle = Article::newFromWikiPage( $rpage, $this->context );
                        $rarticle->setRedirectedFrom( $title );

                        $article = $rarticle;
                        $this->context->setTitle( $target );
                        $this->context->setWikiPage( $article->getPage() );
                    }
                }
            } else {
                // Article may have been changed by hook
                $this->context->setTitle( $article->getTitle() );
                $this->context->setWikiPage( $article->getPage() );
            }
        }

        return $article;
    }

    private function performAction( Page $page, Title $requestTitle ) {
        $request = $this->context->getRequest();
        $output = $this->context->getOutput();
        $title = $this->context->getTitle();
        $user = $this->context->getUser();

        if ( !Hooks::run( 'MediaWikiPerformAction',
                [ $output, $page, $title, $user, $request, $this ] )
        ) {
            return;
        }

        $act = $this->getAction();
        $action = Action::factory( $act, $page, $this->context );

        if ( $action instanceof Action ) {
            // Narrow DB query expectations for this HTTP request
            $trxLimits = $this->config->get( 'TrxProfilerLimits' );
            $trxProfiler = Profiler::instance()->getTransactionProfiler();
            if ( $request->wasPosted() && !$action->doesWrites() ) {
                $trxProfiler->setExpectations( $trxLimits['POST-nonwrite'], __METHOD__ );
            }

            # Let CDN cache things if we can purge them.
            if ( $this->config->get( 'UseSquid' ) &&
                in_array(
                    // Use PROTO_INTERNAL because that's what getCdnUrls() uses
                    wfExpandUrl( $request->getRequestURL(), PROTO_INTERNAL ),
                    $requestTitle->getCdnUrls()
                )
            ) {
                $output->setCdnMaxage( $this->config->get( 'SquidMaxage' ) );
            }

            $action->show();
            return;
        }

        if ( Hooks::run( 'UnknownAction', [ $request->getVal( 'action', 'view' ), $page ] ) ) {
            $output->setStatusCode( 404 );
            $output->showErrorPage( 'nosuchaction', 'nosuchactiontext' );
        }
    }

    public function run() {
        try {
            try {
                $this->main();
            } catch ( ErrorPageError $e ) {
                // Bug 62091: while exceptions are convenient to bubble up GUI errors,
                // they are not internal application faults. As with normal requests, this
                // should commit, print the output, do deferred updates, jobs, and profiling.
                $this->doPreOutputCommit();
                $e->report(); // display the GUI error
            }
        } catch ( Exception $e ) {
            MWExceptionHandler::handleException( $e );
        }

        $this->doPostOutputShutdown( 'normal' );
    }

    public function doPreOutputCommit() {
        self::preOutputCommit( $this->context );
    }

    public static function preOutputCommit( IContextSource $context ) {
        // Either all DBs should commit or none
        ignore_user_abort( true );

        $config = $context->getConfig();

        $factory = wfGetLBFactory();
        // Commit all changes
        $factory->commitMasterChanges(
            __METHOD__,
            // Abort if any transaction was too big
            [ 'maxWriteDuration' => $config->get( 'MaxUserDBWriteDuration' ) ]
        );
        // Record ChronologyProtector positions
        $factory->shutdown();
        wfDebug( __METHOD__ . ': all transactions committed' );

        DeferredUpdates::doUpdates( 'enqueue', DeferredUpdates::PRESEND );
        wfDebug( __METHOD__ . ': pre-send deferred updates completed' );

        // Set a cookie to tell all CDN edge nodes to "stick" the user to the DC that handles this
        // POST request (e.g. the "master" data center). Also have the user briefly bypass CDN so
        // ChronologyProtector works for cacheable URLs.
        $request = $context->getRequest();
        if ( $request->wasPosted() && $factory->hasOrMadeRecentMasterChanges() ) {
            $expires = time() + $config->get( 'DataCenterUpdateStickTTL' );
            $options = [ 'prefix' => '' ];
            $request->response()->setCookie( 'UseDC', 'master', $expires, $options );
            $request->response()->setCookie( 'UseCDNCache', 'false', $expires, $options );
        }

        // Avoid letting a few seconds of slave lag cause a month of stale data. This logic is
        // also intimately related to the value of $wgCdnReboundPurgeDelay.
        if ( $factory->laggedSlaveUsed() ) {
            $maxAge = $config->get( 'CdnMaxageLagged' );
            $context->getOutput()->lowerCdnMaxage( $maxAge );
            $request->response()->header( "X-Database-Lagged: true" );
            wfDebugLog( 'replication', "Lagged DB used; CDN cache TTL limited to $maxAge seconds" );
        }

        // Avoid long-term cache pollution due to message cache rebuild timeouts (T133069)
        if ( MessageCache::singleton()->isDisabled() ) {
            $maxAge = $config->get( 'CdnMaxageSubstitute' );
            $context->getOutput()->lowerCdnMaxage( $maxAge );
            $request->response()->header( "X-Response-Substitute: true" );
        }
    }

    public function doPostOutputShutdown( $mode = 'normal' ) {
        $timing = $this->context->getTiming();
        $timing->mark( 'requestShutdown' );

        // Show visible profiling data if enabled (which cannot be post-send)
        Profiler::instance()->logDataPageOutputOnly();

        $that = $this;
        $callback = function () use ( $that, $mode ) {
            try {
                $that->restInPeace( $mode );
            } catch ( Exception $e ) {
                MWExceptionHandler::handleException( $e );
            }
        };

        // Defer everything else...
        if ( function_exists( 'register_postsend_function' ) ) {
            // https://github.com/facebook/hhvm/issues/1230
            register_postsend_function( $callback );
        } else {
            if ( function_exists( 'fastcgi_finish_request' ) ) {
                fastcgi_finish_request();
            } else {
                // Either all DB and deferred updates should happen or none.
                // The later should not be cancelled due to client disconnect.
                ignore_user_abort( true );
            }

            $callback();
        }
    }

    private function main() {
        global $wgTitle;

        $request = $this->context->getRequest();

        // Send Ajax requests to the Ajax dispatcher.
        if ( $this->config->get( 'UseAjax' ) && $request->getVal( 'action' ) === 'ajax' ) {
            // Set a dummy title, because $wgTitle == null might break things
            $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/performing an AJAX call in '
                . __METHOD__
            );
            $this->context->setTitle( $title );
            $wgTitle = $title;

            $dispatcher = new AjaxDispatcher( $this->config );
            $dispatcher->performAction( $this->context->getUser() );
            return;
        }

        // Get title from request parameters,
        // is set on the fly by parseTitle the first time.
        $title = $this->getTitle();
        $action = $this->getAction();
        $wgTitle = $title;

        // Set DB query expectations for this HTTP request
        $trxLimits = $this->config->get( 'TrxProfilerLimits' );
        $trxProfiler = Profiler::instance()->getTransactionProfiler();
        $trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
        if ( $request->wasPosted() ) {
            $trxProfiler->setExpectations( $trxLimits['POST'], __METHOD__ );
        } else {
            $trxProfiler->setExpectations( $trxLimits['GET'], __METHOD__ );
        }

        // If the user has forceHTTPS set to true, or if the user
        // is in a group requiring HTTPS, or if they have the HTTPS
        // preference set, redirect them to HTTPS.
        // Note: Do this after $wgTitle is setup, otherwise the hooks run from
        // isLoggedIn() will do all sorts of weird stuff.
        if (
            $request->getProtocol() == 'http' &&
            (
                $request->getSession()->shouldForceHTTPS() ||
                // Check the cookie manually, for paranoia
                $request->getCookie( 'forceHTTPS', '' ) ||
                // check for prefixed version that was used for a time in older MW versions
                $request->getCookie( 'forceHTTPS' ) ||
                // Avoid checking the user and groups unless it's enabled.
                (
                    $this->context->getUser()->isLoggedIn()
                    && $this->context->getUser()->requiresHTTPS()
                )
            )
        ) {
            $oldUrl = $request->getFullRequestURL();
            $redirUrl = preg_replace( '#^http://#', 'https://', $oldUrl );

            // ATTENTION: This hook is likely to be removed soon due to overall design of the system.
            if ( Hooks::run( 'BeforeHttpsRedirect', [ $this->context, &$redirUrl ] ) ) {

                if ( $request->wasPosted() ) {
                    // This is weird and we'd hope it almost never happens. This
                    // means that a POST came in via HTTP and policy requires us
                    // redirecting to HTTPS. It's likely such a request is going
                    // to fail due to post data being lost, but let's try anyway
                    // and just log the instance.

                    // @todo FIXME: See if we could issue a 307 or 308 here, need
                    // to see how clients (automated & browser) behave when we do
                    wfDebugLog( 'RedirectedPosts', "Redirected from HTTP to HTTPS: $oldUrl" );
                }
                // Setup dummy Title, otherwise OutputPage::redirect will fail
                $title = Title::newFromText( 'REDIR', NS_MAIN );
                $this->context->setTitle( $title );
                $output = $this->context->getOutput();
                // Since we only do this redir to change proto, always send a vary header
                $output->addVaryHeader( 'X-Forwarded-Proto' );
                $output->redirect( $redirUrl );
                $output->output();
                return;
            }
        }

        if ( $this->config->get( 'UseFileCache' ) && $title->getNamespace() >= 0 ) {
            if ( HTMLFileCache::useFileCache( $this->context ) ) {
                // Try low-level file cache hit
                $cache = new HTMLFileCache( $title, $action );
                if ( $cache->isCacheGood( /* Assume up to date */ ) ) {
                    // Check incoming headers to see if client has this cached
                    $timestamp = $cache->cacheTimestamp();
                    if ( !$this->context->getOutput()->checkLastModified( $timestamp ) ) {
                        $cache->loadFromFileCache( $this->context );
                    }
                    // Do any stats increment/watchlist stuff
                    // Assume we're viewing the latest revision (this should always be the case with file cache)
                    $this->context->getWikiPage()->doViewUpdates( $this->context->getUser() );
                    // Tell OutputPage that output is taken care of
                    $this->context->getOutput()->disable();
                    return;
                }
            }
        }

        // Actually do the work of the request and build up any output
        $this->performRequest();

        // Now commit any transactions, so that unreported errors after
        // output() don't roll back the whole DB transaction and so that
        // we avoid having both success and error text in the response
        $this->doPreOutputCommit();

        // Output everything!
        $this->context->getOutput()->output();
    }

    public function restInPeace( $mode = 'fast' ) {
        // Assure deferred updates are not in the main transaction
        wfGetLBFactory()->commitMasterChanges( __METHOD__ );

        // Ignore things like master queries/connections on GET requests
        // as long as they are in deferred updates (which catch errors).
        Profiler::instance()->getTransactionProfiler()->resetExpectations();

        // Do any deferred jobs
        DeferredUpdates::doUpdates( 'enqueue' );

        // Make sure any lazy jobs are pushed
        JobQueueGroup::pushLazyJobs();

        // Now that everything specific to this request is done,
        // try to occasionally run jobs (if enabled) from the queues
        if ( $mode === 'normal' ) {
            $this->triggerJobs();
        }

        // Log profiling data, e.g. in the database or UDP
        wfLogProfilingData();

        // Commit and close up!
        $factory = wfGetLBFactory();
        $factory->commitMasterChanges( __METHOD__ );
        $factory->shutdown( LBFactory::SHUTDOWN_NO_CHRONPROT );

        wfDebug( "Request ended normally\n" );
    }

    public function triggerJobs() {
        $jobRunRate = $this->config->get( 'JobRunRate' );
        if ( $jobRunRate <= 0 || wfReadOnly() ) {
            return;
        } elseif ( $this->getTitle()->isSpecial( 'RunJobs' ) ) {
            return; // recursion guard
        }

        if ( $jobRunRate < 1 ) {
            $max = mt_getrandmax();
            if ( mt_rand( 0, $max ) > $max * $jobRunRate ) {
                return; // the higher the job run rate, the less likely we return here
            }
            $n = 1;
        } else {
            $n = intval( $jobRunRate );
        }

        $runJobsLogger = LoggerFactory::getInstance( 'runJobs' );

        // Fall back to running the job(s) while the user waits if needed
        if ( !$this->config->get( 'RunJobsAsync' ) ) {
            $runner = new JobRunner( $runJobsLogger );
            $runner->run( [ 'maxJobs' => $n ] );
            return;
        }

        // Do not send request if there are probably no jobs
        try {
            $group = JobQueueGroup::singleton();
            if ( !$group->queuesHaveJobs( JobQueueGroup::TYPE_DEFAULT ) ) {
                return;
            }
        } catch ( JobQueueError $e ) {
            MWExceptionHandler::logException( $e );
            return; // do not make the site unavailable
        }

        $query = [ 'title' => 'Special:RunJobs',
            'tasks' => 'jobs', 'maxjobs' => $n, 'sigexpiry' => time() + 5 ];
        $query['signature'] = SpecialRunJobs::getQuerySignature(
            $query, $this->config->get( 'SecretKey' ) );

        $errno = $errstr = null;
        $info = wfParseUrl( $this->config->get( 'CanonicalServer' ) );
        $host = $info ? $info['host'] : null;
        $port = 80;
        if ( isset( $info['scheme'] ) && $info['scheme'] == 'https' ) {
            $host = "tls://" . $host;
            $port = 443;
        }
        if ( isset( $info['port'] ) ) {
            $port = $info['port'];
        }

        MediaWiki\suppressWarnings();
        $sock = $host ? fsockopen(
            $host,
            $port,
            $errno,
            $errstr,
            // If it takes more than 100ms to connect to ourselves there is a problem...
            0.100
        ) : false;
        MediaWiki\restoreWarnings();

        $invokedWithSuccess = true;
        if ( $sock ) {
            $special = SpecialPageFactory::getPage( 'RunJobs' );
            $url = $special->getPageTitle()->getCanonicalURL( $query );
            $req = (
                "POST $url HTTP/1.1\r\n" .
                "Host: {$info['host']}\r\n" .
                "Connection: Close\r\n" .
                "Content-Length: 0\r\n\r\n"
            );

            $runJobsLogger->info( "Running $n job(s) via '$url'" );
            // Send a cron API request to be performed in the background.
            // Give up if this takes too long to send (which should be rare).
            stream_set_timeout( $sock, 2 );
            $bytes = fwrite( $sock, $req );
            if ( $bytes !== strlen( $req ) ) {
                $invokedWithSuccess = false;
                $runJobsLogger->error( "Failed to start cron API (socket write error)" );
            } else {
                // Do not wait for the response (the script should handle client aborts).
                // Make sure that we don't close before that script reaches ignore_user_abort().
                $start = microtime( true );
                $status = fgets( $sock );
                $sec = microtime( true ) - $start;
                if ( !preg_match( '#^HTTP/\d\.\d 202 #', $status ) ) {
                    $invokedWithSuccess = false;
                    $runJobsLogger->error( "Failed to start cron API: received '$status' ($sec)" );
                }
            }
            fclose( $sock );
        } else {
            $invokedWithSuccess = false;
            $runJobsLogger->error( "Failed to start cron API (socket error $errno): $errstr" );
        }

        // Fall back to running the job(s) while the user waits if needed
        if ( !$invokedWithSuccess ) {
            $runJobsLogger->warning( "Jobs switched to blocking; Special:RunJobs disabled" );

            $runner = new JobRunner( $runJobsLogger );
            $runner->run( [ 'maxJobs'  => $n ] );
        }
    }
}