SpecialRunJobs: Use MediaWiki's built-in async/post-send mode

Disabling OutputPage is fine, but disabling MediaWiki's own
output handling from MediaWiki.php as well (with ignore_user_abort
and ob_flush) made this code incompatible with becoming an API module.

Make use of DeferredUpdates instead, MediaWiki's built-in post-send
mechanism.

Bug: T175146
Change-Id: Ia131341d447fd6501a070da89cd3a2af470e0f7d

diff --git a/includes/specials/SpecialRunJobs.php b/includes/specials/SpecialRunJobs.php
index 73fe70f..375694b 100644 (file)
--- a/includes/specials/SpecialRunJobs.php
+++ b/includes/specials/SpecialRunJobs.php
@@ -39,17 +39,21 @@ class SpecialRunJobs extends UnlistedSpecialPage {
 
        public function execute( $par = '' ) {
                $this->getOutput()->disable();
+
                if ( wfReadOnly() ) {
                        wfHttpError( 423, 'Locked', 'Wiki is in read-only mode.' );
                        return;
-               } elseif ( !$this->getRequest()->wasPosted() ) {
+               }
+
+               // Validate request method
+               if ( !$this->getRequest()->wasPosted() ) {
                        wfHttpError( 400, 'Bad Request', 'Request must be POSTed.' );
                        return;
                }
 
+               // Validate request parameters
                $optional = [ 'maxjobs' => 0, 'maxtime' => 30, 'type' => false, 'async' => true ];
                $required = array_flip( [ 'title', 'tasks', 'signature', 'sigexpiry' ] );
-
                $params = array_intersect_key( $this->getRequest()->getValues(), $required + $optional );
                $missing = array_diff_key( $required, $params );
                if ( count( $missing ) ) {
@@ -59,11 +63,11 @@ class SpecialRunJobs extends UnlistedSpecialPage {
                        return;
                }
 
+               // Validate request signature
                $squery = $params;
                unset( $squery['signature'] );
                $correctSignature = self::getQuerySignature( $squery, $this->getConfig()->get( 'SecretKey' ) );
                $providedSignature = $params['signature'];
-
                $verified = is_string( $providedSignature )
                        && hash_equals( $correctSignature, $providedSignature );
                if ( !$verified || $params['sigexpiry'] < time() ) {
@@ -75,39 +79,34 @@ class SpecialRunJobs extends UnlistedSpecialPage {
                $params += $optional;
 
                if ( $params['async'] ) {
-                       // Client will usually disconnect before checking the response,
-                       // but it needs to know when it is safe to disconnect. Until this
-                       // reaches ignore_user_abort(), it is not safe as the jobs won't run.
-                       ignore_user_abort( true ); // jobs may take a bit of time
                        // HTTP 202 Accepted
                        HttpStatus::header( 202 );
-                       ob_flush();
-                       flush();
-                       // Once the client receives this response, it can disconnect
-                       set_error_handler( function ( $errno, $errstr ) {
-                               if ( strpos( $errstr, 'Cannot modify header information' ) !== false ) {
-                                       return true; // bug T115413
-                               }
-                               // Delegate unhandled errors to the default MediaWiki handler
-                               // so that fatal errors get proper logging (T89169)
-                               return call_user_func_array(
-                                       'MWExceptionHandler::handleError', func_get_args()
-                               );
-                       } );
+                       // Clients are meant to disconnect without waiting for the full response.
+                       // Let the page output happen before the jobs start, so that clients know it's
+                       // safe to disconnect. MediaWiki::preOutputCommit() calls ignore_user_abort()
+                       // or similar to make sure we stay alive to run the deferred update.
+                       DeferredUpdates::addUpdate(
+                               new TransactionRoundDefiningUpdate(
+                                       function () use ( $params ) {
+                                               $this->doRun( $params );
+                                       },
+                                       __METHOD__
+                               ),
+                               DeferredUpdates::POSTSEND
+                       );
+               } else {
+                       $this->doRun( $params );
+                       print "Done\n";
                }
+       }
 
-               // Do all of the specified tasks...
-               if ( in_array( 'jobs', explode( '|', $params['tasks'] ) ) ) {
-                       $runner = new JobRunner( LoggerFactory::getInstance( 'runJobs' ) );
-                       $runner->run( [
-                               'type'     => $params['type'],
-                               'maxJobs'  => $params['maxjobs'] ? $params['maxjobs'] : 1,
-                               'maxTime'  => $params['maxtime'] ? $params['maxjobs'] : 30
-                       ] );
-                       if ( !$params['async'] ) {
-                               print "Done\n";
-                       }
-               }
+       protected function doRun( array $params ) {
+               $runner = new JobRunner( LoggerFactory::getInstance( 'runJobs' ) );
+               $runner->run( [
+                       'type'     => $params['type'],
+                       'maxJobs'  => $params['maxjobs'] ?: 1,
+                       'maxTime'  => $params['maxtime'] ?: 30
+               ] );
        }
 
        /**