[JobQueue] Use target wiki configuration for some key functions.

* getQueueTypes() now gets the config of the target wiki.
  Previously, for WMF, if an extension using jobs was not
  on aawiki, those job queues would not be seen by nextJobDB.
* Also fixed nextJobDB.php so that it no longer only considers
  jobs types known to aawiki for picking a DB for default jobs.
* Note that $wgJobTypesExcludedFromDefaultQueue should be global.
* This adds a SiteConfiguration::getConfig() function, which calls
  a new getConfiguration.php script.

Change-Id: I7e6904ead17efa407291f423a2b18e3c866d55fd

includes/SiteConfiguration.php

@@ -161,6 +161,12 @@ class SiteConfiguration {
 	 */
 	public $siteParamsCallback = null;
 
+	/**
+	 * Configuration cache for getConfig()
+	 * @var array
+	 */
+	protected $cfgCache = array();
+
 	/**
 	 * Retrieves a configuration setting for a given wiki.
 	 * @param $settingName String ID of the setting name to retrieve
@@ -486,6 +492,67 @@ class SiteConfiguration {
 		return array( $site, $lang );
 	}
 
+	/**
+	 * Get the resolved (post-setup) configuration of a potentially foreign wiki.
+	 * For foreign wikis, this is expensive, and only works if maintenance
+	 * scripts are setup to handle the --wiki parameter such as in wiki farms.
+	 *
+	 * @param string $wiki
+	 * @param array|string $settings A setting name or array of setting names
+	 * @return Array|mixed Array if $settings is an array, otherwise the value
+	 * @throws MWException
+	 * @since 1.21
+	 */
+	public function getConfig( $wiki, $settings ) {
+		global $IP;
+
+		$multi = is_array( $settings );
+		$settings = (array)$settings;
+		if ( $wiki === wfWikiID() ) { // $wiki is this wiki
+			$res = array();
+			foreach ( $settings as $name ) {
+				if ( !preg_match( '/^wg[A-Z]/', $name ) ) {
+					throw new MWException( "Variable '$name' does start with 'wg'." );
+				} elseif ( !isset( $GLOBALS[$name] ) ) {
+					throw new MWException( "Variable '$name' is not set." );
+				}
+				$res[$name] = $GLOBALS[$name];
+			}
+		} else { // $wiki is a foreign wiki
+			if ( isset( $this->cfgCache[$wiki] ) ) {
+				$res = array_intersect_key( $this->cfgCache[$wiki], array_flip( $settings ) );
+				if ( count( $res ) == count( $settings ) ) {
+					return $res; // cache hit
+				}
+			} elseif ( !in_array( $wiki, $this->wikis ) ) {
+				throw new MWException( "No such wiki '$wiki'." );
+			} else {
+				$this->cfgCache[$wiki] = array();
+			}
+			$retVal = 1;
+			$cmd = wfShellWikiCmd(
+				"$IP/maintenance/getConfiguration.php",
+				array(
+					'--wiki', $wiki,
+					'--settings', implode( ' ', $settings ),
+					'--format', 'PHP'
+				)
+			);
+			// ulimit5.sh breaks this call
+			$data = trim( wfShellExec( $cmd, $retVal, array(), array( 'memory' => 0 ) ) );
+			if ( $retVal != 0 || !strlen( $data ) ) {
+				throw new MWException( "Failed to run getConfiguration.php." );
+			}
+			$res = unserialize( $data );
+			if ( !is_array( $res ) ) {
+				throw new MWException( "Failed to unserialize configuration array." );
+			}
+			$this->cfgCache[$wiki] = $this->cfgCache[$wiki] + $res;
+		}
+
+		return $multi ? $res : current( $res );
+	}
+
 	/**
 	 * Returns true if the given vhost is handled locally.
 	 * @param $vhost String

includes/job/JobQueueGroup.php

@@ -200,9 +200,7 @@ class JobQueueGroup {
 	 * @return array List of strings
 	 */
 	public function getQueueTypes() {
-		global $wgJobClasses;
-
-		return array_keys( $wgJobClasses );
+		return array_keys( $this->getCachedConfigVar( 'wgJobClasses' ) );
 	}
 
 	/**
@@ -284,4 +282,23 @@ class JobQueueGroup {
 
 		return $count;
 	}
+
+	private function getCachedConfigVar( $name ) {
+		global $wgConf, $wgMemc;
+
+		if ( $this->wiki === wfWikiID() ) {
+			return $GLOBALS[$name]; // common case
+		} else {
+			list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+			$key = wfForeignMemcKey( $db, $prefix, 'configvalue', $name );
+			$value = $wgMemc->get( $key ); // ('v' => ...) or false
+			if ( is_array( $value ) ) {
+				return $value['v'];
+			} else {
+				$value = $wgConf->getConfig( $this->wiki, $name );
+				$wgMemc->set( $key, array( 'v' => $value ), 86400 + mt_rand( 0, 86400 ) );
+				return $value;
+			}
+		}
+	}
 }

maintenance/getConfiguration.php

@@ -0,0 +1,89 @@
+<?php
+/**
+ * Print serialized output of MediaWiki config vars
+ *
+ * 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
+ * @ingroup Maintenance
+ * @author Tim Starling
+ * @author Antoine Musso
+ */
+
+require_once( __DIR__ . '/Maintenance.php' );
+
+/**
+ * Print serialized output of MediaWiki config vars
+ *
+ * @ingroup Maintenance
+ */
+class GetConfiguration extends Maintenance {
+	public function __construct() {
+		parent::__construct();
+		$this->mDescription = "Get serialized MediaWiki site configuration";
+		$this->addOption( 'settings', 'Space-separated list of wg* variables', true, true );
+		$this->addOption( 'format', 'PHP or JSON', true, true );
+		$this->addOption( 'wiki', 'Wiki ID', true, true );
+	}
+
+	public function execute() {
+		$res = array();
+		foreach ( explode( ' ', $this->getOption( 'settings' ) ) as $name ) {
+			if ( !preg_match( '/^wg[A-Z]/', $name ) ) {
+				throw new MWException( "Variable '$name' does start with 'wg'." );
+			} elseif ( !isset( $GLOBALS[$name] ) ) {
+				throw new MWException( "Variable '$name' is not set." );
+			} elseif ( !$this->isAllowedVariable( $GLOBALS[$name] ) ) {
+				throw new MWException( "Variable '$name' includes non-array, non-scalar, items." );
+			}
+			$res[$name] = $GLOBALS[$name];
+		}
+
+		$out = null;
+		switch( $this->getOption( 'format' ) ) {
+			case 'PHP':
+				$out = serialize( $res );
+				break;
+			case 'JSON':
+				$out = FormatJson::encode( $res );
+				break;
+			default:
+				throw new MWException( "Invalid serialization format given." );
+		}
+		if ( !is_string( $out ) ) {
+			throw new MWException( "Failed to serialize the requested settings." );
+		}
+
+		$this->output( $out . "\n" );
+	}
+
+	private function isAllowedVariable( $value ) {
+		if ( is_array( $value ) ) {
+			foreach ( $value as $k => $v ) {
+				if ( !$this->isAllowedVariable( $v ) ) {
+					return false;
+				}
+			}
+			return true;
+		} elseif ( is_scalar( $value ) ) {
+			return true;
+		}
+		return false;
+	}
+}
+
+$maintClass = "GetConfiguration";
+require_once( RUN_MAINTENANCE_IF_MAIN );

maintenance/nextJobDB.php

@@ -37,15 +37,16 @@ class nextJobDB extends Maintenance {
 	}
 
 	public function execute() {
-		global $wgMemc;
+		global $wgMemc, $wgJobTypesExcludedFromDefaultQueue;
 
 		$type = false; // job type required/picked
+
 		if ( $this->hasOption( 'types' ) ) {
 			$types = explode( ' ', $this->getOption( 'types' ) );
 		} elseif ( $this->hasOption( 'type' ) ) {
 			$types = array( $this->getOption( 'type' ) );
 		} else {
-			$types = JobQueueGroup::singleton()->getDefaultQueueTypes();
+			$types = false;
 		}
 
 		// Handle any required periodic queue maintenance
@@ -64,7 +65,10 @@ class nextJobDB extends Maintenance {
 			// Flatten the tree of candidates into a flat list so that a random
 			// item can be selected, weighing each queue (type/db tuple) equally.
 			foreach ( $pendingDBs as $type => $dbs ) {
-				if ( in_array( $type, $types ) ) {
+				if (
+					( is_array( $types ) && in_array( $type, $types ) ) ||
+					( $types === false && !in_array( $type, $wgJobTypesExcludedFromDefaultQueue ) )
+				) {
 					foreach ( $dbs as $db ) {
 						$candidates[] = array( $type, $db );
 					}