From 62216932c197f1c248ca2d95bc230f87a79ccd71 Mon Sep 17 00:00:00 2001
From: Yuri Astrakhan <yuriastrakhan@gmail.com>
Date: Fri, 8 Feb 2013 15:39:40 -0500
Subject: [PATCH] API PageSet allows generator for non-query modules

* PageSet can now be used in any action to process titles/pageids/revids
or any generator, redirects resolution, and converttitle functionality.
* action=purge proper usage of MustBePosted()
* Add supports for all pageset capabilities - generators, redirects, converttitles to
  action=purge and action=setnotificationtimestamp
* BREAKING CHANGE: ApiPageSet constructor now has two params instead of three, with only the
  first one keeping its meaning. ApiPageSet is now derived from ApiBase.
* BREAKING CHANGE: ApiQuery::newGenerator() and executeGeneratorModule() were deleted.

Change-Id: I7a3d7b6eb015d21ec1a9b9d9c6af9d97663f3f9a
---
 RELEASE-NOTES-1.21                            |   7 +
 docs/hooks.txt                                |   1 +
 includes/api/ApiBase.php                      |  37 +-
 includes/api/ApiMain.php                      |   2 +-
 includes/api/ApiPageSet.php                   | 422 +++++++++++++-----
 includes/api/ApiParamInfo.php                 |   2 +-
 includes/api/ApiPurge.php                     | 128 ++++--
 includes/api/ApiQuery.php                     | 254 ++---------
 includes/api/ApiQueryAllImages.php            |   2 +-
 includes/api/ApiQueryBase.php                 |  35 +-
 includes/api/ApiSetNotificationTimestamp.php  |  44 +-
 .../phpunit/includes/api/ApiGeneratorTest.php |   4 +-
 .../includes/api/PrefixUniquenessTest.php     |   2 +-
 13 files changed, 541 insertions(+), 399 deletions(-)

diff --git a/RELEASE-NOTES-1.21 b/RELEASE-NOTES-1.21
index 6ffe112e7c..d1976ddb5d 100644
--- a/RELEASE-NOTES-1.21
+++ b/RELEASE-NOTES-1.21
@@ -206,6 +206,8 @@ production.
   that the imagerepository property will no longer be set on page objects not
   processed in the current query (i.e. non-images or those skipped due to
   iicontinue).
+* Add supports for all pageset capabilities - generators, redirects, converttitles to
+  action=purge and action=setnotificationtimestamp.
 
 === API internal changes in 1.21 ===
 * For debugging only, a new global $wgDebugAPI removes many API restrictions when true.
@@ -213,6 +215,11 @@ production.
   Whenever enabled, a warning will also be added to all output.
 * ApiModuleManager now handles all submodules (actions,props,lists) and instantiation
 * Query stores prop/list/meta as submodules
+* ApiPageSet can now be used in any action to process titles/pageids/revids or any generator.
+* BREAKING CHANGE: ApiPageSet constructor now has two params instead of three, with only the
+  first one keeping its meaning. ApiPageSet is now derived from ApiBase.
+* BREAKING CHANGE: ApiQuery::newGenerator() and executeGeneratorModule() were deleted.
+* ApiQueryGeneratorBase::setGeneratorMode() now requires a pageset param.
 
 === Languages updated in 1.21 ===
 
diff --git a/docs/hooks.txt b/docs/hooks.txt
index f9274a5ea1..28eedf4725 100644
--- a/docs/hooks.txt
+++ b/docs/hooks.txt
@@ -355,6 +355,7 @@ $text : the new text of the article (has yet to be saved)
 'APIGetAllowedParams': Use this hook to modify a module's parameters.
 &$module: ApiBase Module object
 &$params: Array of parameters
+$flags: int zero or OR-ed flags like ApiBase::GET_VALUES_FOR_HELP
 
 'APIGetDescription': Use this hook to modify a module's description.
 &$module: ApiBase Module object
diff --git a/includes/api/ApiBase.php b/includes/api/ApiBase.php
index 743fef0433..abb43e8d3e 100644
--- a/includes/api/ApiBase.php
+++ b/includes/api/ApiBase.php
@@ -66,7 +66,15 @@ abstract class ApiBase extends ContextSource {
 	const LIMIT_SML1 = 50; // Slow query, std user limit
 	const LIMIT_SML2 = 500; // Slow query, bot/sysop limit
 
+	/**
+	 * getAllowedParams() flag: When set, the result could take longer to generate,
+	 * but should be more thorough. E.g. get the list of generators for ApiSandBox extension
+	 * @since 1.21
+	 */
+	const GET_VALUES_FOR_HELP = 1;
+
 	private $mMainModule, $mModuleName, $mModulePrefix;
+	private $mSlaveDB = null;
 	private $mParamCache = array();
 
 	/**
@@ -358,7 +366,7 @@ abstract class ApiBase extends ContextSource {
 	 * @return string or false
 	 */
 	public function makeHelpMsgParameters() {
-		$params = $this->getFinalParams();
+		$params = $this->getFinalParams( ApiBase::GET_VALUES_FOR_HELP );
 		if ( $params ) {
 
 			$paramsDescription = $this->getFinalParamDescription();
@@ -506,15 +514,22 @@ abstract class ApiBase extends ContextSource {
 	 * value) or (parameter name) => (array with PARAM_* constants as keys)
 	 * Don't call this function directly: use getFinalParams() to allow
 	 * hooks to modify parameters as needed.
+	 *
+	 * Some derived classes may choose to handle an integer $flags parameter
+	 * in the overriding methods. Callers of this method can pass zero or
+	 * more OR-ed flags like GET_VALUES_FOR_HELP.
+	 *
 	 * @return array|bool
 	 */
-	protected function getAllowedParams() {
+	protected function getAllowedParams( /* $flags = 0 */ ) {
+		// int $flags is not declared because it causes "Strict standards"
+		// warning. Most derived classes do not implement it.
 		return false;
 	}
 
 	/**
 	 * Returns an array of parameter descriptions.
-	 * Don't call this functon directly: use getFinalParamDescription() to
+	 * Don't call this function directly: use getFinalParamDescription() to
 	 * allow hooks to modify descriptions as needed.
 	 * @return array|bool False on no parameter descriptions
 	 */
@@ -526,11 +541,13 @@ abstract class ApiBase extends ContextSource {
 	 * Get final list of parameters, after hooks have had a chance to
 	 * tweak it as needed.
 	 *
+	 * @param $flags int Zero or more flags like GET_VALUES_FOR_HELP
 	 * @return array|Bool False on no parameters
+	 * @since 1.21 $flags param added
 	 */
-	public function getFinalParams() {
-		$params = $this->getAllowedParams();
-		wfRunHooks( 'APIGetAllowedParams', array( &$this, &$params ) );
+	public function getFinalParams( $flags = 0 ) {
+		$params = $this->getAllowedParams( $flags );
+		wfRunHooks( 'APIGetAllowedParams', array( &$this, &$params, $flags ) );
 		return $params;
 	}
 
@@ -1650,10 +1667,16 @@ abstract class ApiBase extends ContextSource {
 	}
 
 	/**
+	 * Gets a default slave database connection object
 	 * @return DatabaseBase
 	 */
 	protected function getDB() {
-		return wfGetDB( DB_SLAVE, 'api' );
+		if ( !isset( $this->mSlaveDB ) ) {
+			$this->profileDBIn();
+			$this->mSlaveDB = wfGetDB( DB_SLAVE, 'api' );
+			$this->profileDBOut();
+		}
+		return $this->mSlaveDB;
 	}
 
 	/**
diff --git a/includes/api/ApiMain.php b/includes/api/ApiMain.php
index 3535cd04e0..953cec81f4 100644
--- a/includes/api/ApiMain.php
+++ b/includes/api/ApiMain.php
@@ -936,7 +936,7 @@ class ApiMain extends ApiBase {
 	protected function printResult( $isError ) {
 		global $wgDebugAPI;
 		if( $wgDebugAPI !== false ) {
-			$this->getResult()->setWarning( 'SECURITY WARNING: $wgDebugAPI is enabled' );
+			$this->setWarning( 'SECURITY WARNING: $wgDebugAPI is enabled' );
 		}
 
 		$this->getResult()->cleanUpUTF8();
diff --git a/includes/api/ApiPageSet.php b/includes/api/ApiPageSet.php
index 4dbccc6c9d..3945104123 100644
--- a/includes/api/ApiPageSet.php
+++ b/includes/api/ApiPageSet.php
@@ -4,7 +4,7 @@
  *
  * Created on Sep 24, 2006
  *
- * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
+ * Copyright © 2006, 2013 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
  *
  * 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
@@ -36,52 +36,140 @@
  * the second instance for all their work.
  *
  * @ingroup API
+ * @since 1.21 derives from ApiBase instead of ApiQueryBase
  */
-class ApiPageSet extends ApiQueryBase {
+class ApiPageSet extends ApiBase {
 
-	private $mAllPages; // [ns][dbkey] => page_id or negative when missing
-	private $mTitles, $mGoodTitles, $mMissingTitles, $mInvalidTitles;
-	private $mMissingPageIDs, $mRedirectTitles, $mSpecialTitles;
-	private $mNormalizedTitles, $mInterwikiTitles;
-	private $mResolveRedirects, $mPendingRedirectIDs;
-	private $mConvertTitles, $mConvertedTitles;
-	private $mGoodRevIDs, $mMissingRevIDs;
-	private $mFakePageId;
+	/**
+	 * Constructor flag: The new instance of ApiPageSet will ignore the 'generator=' parameter
+	 * @since 1.21
+	 */
+	const DISABLE_GENERATORS = 1;
 
-	private $mRequestedPageFields;
+	private $mDbSource, $mParams;
+	private $mResolveRedirects, $mConvertTitles, $mAllowGenerator;
+
+	private $mAllPages = array(); // [ns][dbkey] => page_id or negative when missing
+	private $mTitles = array();
+	private $mGoodTitles = array();
+	private $mMissingTitles = array();
+	private $mInvalidTitles = array();
+	private $mMissingPageIDs = array();
+	private $mRedirectTitles = array();
+	private $mSpecialTitles = array();
+	private $mNormalizedTitles = array();
+	private $mInterwikiTitles = array();
+	private $mPendingRedirectIDs = array();
+	private $mConvertedTitles = array();
+	private $mGoodRevIDs = array();
+	private $mMissingRevIDs = array();
+	private $mFakePageId = -1;
+	private $mCacheMode = 'public';
+	private $mRequestedPageFields = array();
 
 	/**
 	 * Constructor
-	 * @param $query ApiBase
-	 * @param $resolveRedirects bool Whether redirects should be resolved
-	 * @param $convertTitles bool
-	 */
-	public function __construct( $query, $resolveRedirects = false, $convertTitles = false ) {
-		parent::__construct( $query, 'query' );
-
-		$this->mAllPages = array();
-		$this->mTitles = array();
-		$this->mGoodTitles = array();
-		$this->mMissingTitles = array();
-		$this->mInvalidTitles = array();
-		$this->mMissingPageIDs = array();
-		$this->mRedirectTitles = array();
-		$this->mNormalizedTitles = array();
-		$this->mInterwikiTitles = array();
-		$this->mGoodRevIDs = array();
-		$this->mMissingRevIDs = array();
-		$this->mSpecialTitles = array();
-
-		$this->mRequestedPageFields = array();
-		$this->mResolveRedirects = $resolveRedirects;
-		if ( $resolveRedirects ) {
-			$this->mPendingRedirectIDs = array();
-		}
+	 * @param $dbSource ApiBase Module implementing getDB().
+	 *        Allows PageSet to reuse existing db connection from the shared state like ApiQuery.
+	 * @param $flags int Zero or more flags like DISABLE_GENERATORS
+	 * @since 1.21 accepts $flags instead of two boolean values
+	 */
+	public function __construct( ApiBase $dbSource, $flags = 0 ) {
+		parent::__construct( $dbSource->getMain(), $dbSource->getModuleName() );
+		$this->mDbSource = $dbSource;
+		$this->mAllowGenerator = ( $flags & ApiPageSet::DISABLE_GENERATORS ) == 0;
 
-		$this->mConvertTitles = $convertTitles;
-		$this->mConvertedTitles = array();
+		$this->profileIn();
+		$this->mParams = $this->extractRequestParams();
+		$this->mResolveRedirects = $this->mParams['redirects'];
+		$this->mConvertTitles = $this->mParams['converttitles'];
+		$this->profileOut();
+	}
 
-		$this->mFakePageId = - 1;
+	/**
+	 * Populate the PageSet from the request parameters.
+	 */
+	public function execute() {
+		$this->profileIn();
+
+		$generatorName = $this->mAllowGenerator ? $this->mParams['generator'] : null;
+		if ( isset( $generatorName ) ) {
+			$dbSource = $this->mDbSource;
+			$isQuery = $dbSource instanceof ApiQuery;
+			if ( !$isQuery ) {
+				// If the parent container of this pageset is not ApiQuery, we must create it to run generator
+				$dbSource = $this->getMain()->getModuleManager()->getModule( 'query' );
+				// Enable profiling for query module because it will be used for db sql profiling
+				$dbSource->profileIn();
+			}
+			$generator = $dbSource->getModuleManager()->getModule( $generatorName, null, true );
+			if ( $generator === null ) {
+				$this->dieUsage( 'Unknown generator=' . $generatorName, 'badgenerator' );
+			}
+			if ( !$generator instanceof ApiQueryGeneratorBase ) {
+				$this->dieUsage( "Module $generatorName cannot be used as a generator", 'badgenerator' );
+			}
+			// Create a temporary pageset to store generator's output,
+			// add any additional fields generator may need, and execute pageset to populate titles/pageids
+			$tmpPageSet = new ApiPageSet( $dbSource, ApiPageSet::DISABLE_GENERATORS );
+			$generator->setGeneratorMode( $tmpPageSet );
+			$this->mCacheMode = $generator->getCacheMode( $generator->extractRequestParams() );
+			$generator->requestExtraData( $tmpPageSet );
+			$tmpPageSet->execute();
+
+			// populate this pageset with the generator output
+			$this->profileOut();
+			$generator->profileIn();
+			$generator->executeGenerator( $this );
+			wfRunHooks( 'APIQueryGeneratorAfterExecute', array( &$generator, &$this ) );
+			$this->resolvePendingRedirects();
+			$generator->profileOut();
+			$this->profileIn();
+
+			if ( !$isQuery ) {
+				// If this pageset is not part of the query, we called profileIn() above
+				$dbSource->profileOut();
+			}
+		} else {
+			// Only one of the titles/pageids/revids is allowed at the same time
+			$dataSource = null;
+			if ( isset( $this->mParams['titles'] ) ) {
+				$dataSource = 'titles';
+			}
+			if ( isset( $this->mParams['pageids'] ) ) {
+				if ( isset( $dataSource ) ) {
+					$this->dieUsage( "Cannot use 'pageids' at the same time as '$dataSource'", 'multisource' );
+				}
+				$dataSource = 'pageids';
+			}
+			if ( isset( $this->mParams['revids'] ) ) {
+				if ( isset( $dataSource ) ) {
+					$this->dieUsage( "Cannot use 'revids' at the same time as '$dataSource'", 'multisource' );
+				}
+				$dataSource = 'revids';
+			}
+			// Populate page information with the original user input
+			switch( $dataSource ) {
+				case 'titles':
+					$this->initFromTitles( $this->mParams['titles'] );
+					break;
+				case 'pageids':
+					$this->initFromPageIds( $this->mParams['pageids'] );
+					break;
+				case 'revids':
+					if ( $this->mResolveRedirects ) {
+						$this->setWarning( 'Redirect resolution cannot be used together with the revids= parameter. ' .
+							'Any redirects the revids= point to have not been resolved.' );
+					}
+					$this->mResolveRedirects = false;
+					$this->initFromRevIDs( $this->mParams['revids'] );
+					break;
+				default:
+					// Do nothing - some queries do not need any of the data sources.
+					break;
+			}
+		}
+		$this->profileOut();
 	}
 
 	/**
@@ -93,8 +181,8 @@ class ApiPageSet extends ApiQueryBase {
 	}
 
 	/**
-	 * Request an additional field from the page table. Must be called
-	 * before execute()
+	 * Request an additional field from the page table.
+	 * Must be called before execute()
 	 * @param $fieldName string Field name
 	 */
 	public function requestField( $fieldName ) {
@@ -207,13 +295,38 @@ class ApiPageSet extends ApiQueryBase {
 
 	/**
 	 * Get a list of redirect resolutions - maps a title to its redirect
-	 * target.
-	 * @return array prefixed_title (string) => Title object
+	 * target, as an array of output-ready arrays
+	 * @return array
 	 */
 	public function getRedirectTitles() {
 		return $this->mRedirectTitles;
 	}
 
+	/**
+	 * Get a list of redirect resolutions - maps a title to its redirect
+	 * target.
+	 * @param $result ApiResult
+	 * @return array of prefixed_title (string) => Title object
+	 * @since 1.21
+	 */
+	public function getRedirectTitlesAsResult( $result = null ) {
+		$values = array();
+		foreach ( $this->getRedirectTitles() as $titleStrFrom => $titleTo ) {
+			$r = array(
+				'from' => strval( $titleStrFrom ),
+				'to' => $titleTo->getPrefixedText(),
+			);
+			if ( $titleTo->getFragment() !== '' ) {
+				$r['tofragment'] = $titleTo->getFragment();
+			}
+			$values[] = $r;
+		}
+		if ( !empty( $values ) && $result ) {
+			$result->setIndexedTagName( $values, 'r' );
+		}
+		return $values;
+	}
+
 	/**
 	 * Get a list of title normalizations - maps a title to its normalized
 	 * version.
@@ -223,6 +336,27 @@ class ApiPageSet extends ApiQueryBase {
 		return $this->mNormalizedTitles;
 	}
 
+	/**
+	 * Get a list of title normalizations - maps a title to its normalized
+	 * version in the form of result array.
+	 * @param $result ApiResult
+	 * @return array of raw_prefixed_title (string) => prefixed_title (string)
+	 * @since 1.21
+	 */
+	public function getNormalizedTitlesAsResult( $result = null  ) {
+		$values = array();
+		foreach ( $this->getNormalizedTitles() as $rawTitleStr => $titleStr ) {
+			$values[] = array(
+				'from' => $rawTitleStr,
+				'to' => $titleStr
+			);
+		}
+		if ( !empty( $values ) && $result ) {
+			$result->setIndexedTagName( $values, 'n' );
+		}
+		return $values;
+	}
+
 	/**
 	 * Get a list of title conversions - maps a title to its converted
 	 * version.
@@ -232,6 +366,27 @@ class ApiPageSet extends ApiQueryBase {
 		return $this->mConvertedTitles;
 	}
 
+	/**
+	 * Get a list of title conversions - maps a title to its converted
+	 * version as a result array.
+	 * @param $result ApiResult
+	 * @return array of (from, to) strings
+	 * @since 1.21
+	 */
+	public function getConvertedTitlesAsResult( $result = null ) {
+		$values = array();
+		foreach ( $this->getConvertedTitles() as $rawTitleStr => $titleStr ) {
+			$values[] = array(
+				'from' => $rawTitleStr,
+				'to' => $titleStr
+			);
+		}
+		if ( !empty( $values ) && $result ) {
+			$result->setIndexedTagName( $values, 'c' );
+		}
+		return $values;
+	}
+
 	/**
 	 * Get a list of interwiki titles - maps a title to its interwiki
 	 * prefix.
@@ -241,6 +396,33 @@ class ApiPageSet extends ApiQueryBase {
 		return $this->mInterwikiTitles;
 	}
 
+	/**
+	 * Get a list of interwiki titles - maps a title to its interwiki
+	 * prefix as result.
+	 * @param $result ApiResult
+	 * @param $iwUrl boolean
+	 * @return array raw_prefixed_title (string) => interwiki_prefix (string)
+	 * @since 1.21
+	 */
+	public function getInterwikiTitlesAsResult( $result = null, $iwUrl = false ) {
+		$values = array();
+		foreach ( $this->getInterwikiTitles() as $rawTitleStr => $interwikiStr ) {
+			$item = array(
+				'title' => $rawTitleStr,
+				'iw' => $interwikiStr,
+			);
+			if ( $iwUrl ) {
+				$title = Title::newFromText( $rawTitleStr );
+				$item['url'] = $title->getFullURL( '', false, PROTO_CURRENT );
+			}
+			$values[] = $item;
+		}
+		if ( !empty( $values ) && $result ) {
+			$result->setIndexedTagName( $values, 'i' );
+		}
+		return $values;
+	}
+
 	/**
 	 * Get the list of revision IDs (requested with the revids= parameter)
 	 * @return array revID (int) => pageID (int)
@@ -257,6 +439,25 @@ class ApiPageSet extends ApiQueryBase {
 		return $this->mMissingRevIDs;
 	}
 
+	/**
+	 * Revision IDs that were not found in the database as result array.
+	 * @param $result ApiResult
+	 * @return array of revision IDs
+	 * @since 1.21
+	 */
+	public function getMissingRevisionIDsAsResult( $result = null ) {
+		$values = array();
+		foreach ( $this->getMissingRevisionIDs() as $revid ) {
+			$values[$revid] = array(
+				'revid' => $revid
+			);
+		}
+		if ( !empty( $values ) && $result ) {
+			$result->setIndexedTagName( $values, 'rev' );
+		}
+		return $values;
+	}
+
 	/**
 	 * Get the list of titles with negative namespace
 	 * @return array Title
@@ -273,53 +474,6 @@ class ApiPageSet extends ApiQueryBase {
 		return count( $this->getRevisionIDs() );
 	}
 
-	/**
-	 * Populate the PageSet from the request parameters.
-	 */
-	public function execute() {
-		$this->profileIn();
-		$params = $this->extractRequestParams();
-
-		// Only one of the titles/pageids/revids is allowed at the same time
-		$dataSource = null;
-		if ( isset( $params['titles'] ) ) {
-			$dataSource = 'titles';
-		}
-		if ( isset( $params['pageids'] ) ) {
-			if ( isset( $dataSource ) ) {
-				$this->dieUsage( "Cannot use 'pageids' at the same time as '$dataSource'", 'multisource' );
-			}
-			$dataSource = 'pageids';
-		}
-		if ( isset( $params['revids'] ) ) {
-			if ( isset( $dataSource ) ) {
-				$this->dieUsage( "Cannot use 'revids' at the same time as '$dataSource'", 'multisource' );
-			}
-			$dataSource = 'revids';
-		}
-
-		switch ( $dataSource ) {
-			case 'titles':
-				$this->initFromTitles( $params['titles'] );
-				break;
-			case 'pageids':
-				$this->initFromPageIds( $params['pageids'] );
-				break;
-			case 'revids':
-				if ( $this->mResolveRedirects ) {
-					$this->setWarning( 'Redirect resolution cannot be used together with the revids= parameter. ' .
-					'Any redirects the revids= point to have not been resolved.' );
-				}
-				$this->mResolveRedirects = false;
-				$this->initFromRevIDs( $params['revids'] );
-				break;
-			default:
-				// Do nothing - some queries do not need any of the data sources.
-				break;
-		}
-		$this->profileOut();
-	}
-
 	/**
 	 * Populate this PageSet from a list of Titles
 	 * @param $titles array of Title objects
@@ -385,12 +539,11 @@ class ApiPageSet extends ApiQueryBase {
 	}
 
 	/**
-	 * Resolve redirects, if applicable
+	 * Do not use, does nothing, will be removed
+	 * @deprecated 1.21
 	 */
 	public function finishPageSetGeneration() {
-		$this->profileIn();
-		$this->resolvePendingRedirects();
-		$this->profileOut();
+		wfDeprecated( __METHOD__, '1.21' );
 	}
 
 	/**
@@ -437,7 +590,7 @@ class ApiPageSet extends ApiQueryBase {
 	 * @param $pageids array of page IDs
 	 */
 	private function initFromPageIds( $pageids ) {
-		if ( !count( $pageids ) ) {
+		if ( !$pageids ) {
 			return;
 		}
 
@@ -447,7 +600,7 @@ class ApiPageSet extends ApiQueryBase {
 		$pageids = self::getPositiveIntegers( $pageids );
 
 		$res = null;
-		if ( count( $pageids ) ) {
+		if ( !empty( $pageids ) ) {
 			$set = array(
 				'page_id' => $pageids
 			);
@@ -499,7 +652,7 @@ class ApiPageSet extends ApiQueryBase {
 				$this->processDbRow( $row );
 
 				// Need gender information
-				if( MWNamespace::hasGenderDistinction( $row->page_namespace ) ) {
+				if ( MWNamespace::hasGenderDistinction( $row->page_namespace ) ) {
 					$usernames[] = $row->page_title;
 				}
 			}
@@ -518,7 +671,7 @@ class ApiPageSet extends ApiQueryBase {
 						$this->mTitles[] = $title;
 
 						// need gender information
-						if( MWNamespace::hasGenderDistinction( $ns ) ) {
+						if ( MWNamespace::hasGenderDistinction( $ns ) ) {
 							$usernames[] = $dbkey;
 						}
 					}
@@ -544,7 +697,7 @@ class ApiPageSet extends ApiQueryBase {
 	 * @param $revids array of revision IDs
 	 */
 	private function initFromRevIDs( $revids ) {
-		if ( !count( $revids ) ) {
+		if ( !$revids ) {
 			return;
 		}
 
@@ -555,7 +708,7 @@ class ApiPageSet extends ApiQueryBase {
 
 		$revids = self::getPositiveIntegers( $revids );
 
-		if ( count( $revids ) ) {
+		if ( !empty( $revids ) ) {
 			$tables = array( 'revision', 'page' );
 			$fields = array( 'rev_id', 'rev_page' );
 			$where = array( 'rev_id' => $revids, 'rev_page = page_id' );
@@ -669,6 +822,23 @@ class ApiPageSet extends ApiQueryBase {
 		return $lb;
 	}
 
+	/**
+	 * Get the cache mode for the data generated by this module.
+	 * All PageSet users should take into account whether this returns a more-restrictive
+	 * cache mode than the using module itself. For possible return values and other
+	 * details about cache modes, see ApiMain::setCacheMode()
+	 *
+	 * Public caching will only be allowed if *all* the modules that supply
+	 * data for a given request return a cache mode of public.
+	 *
+	 * @param $params
+	 * @return string
+	 * @since 1.21
+	 */
+	public function getCacheMode( $params = null ) {
+		return $this->mCacheMode;
+	}
+
 	/**
 	 * Given an array of title strings, convert them into Title objects.
 	 * Alternativelly, an array of Title objects may be given.
@@ -742,6 +912,14 @@ class ApiPageSet extends ApiQueryBase {
 		return $linkBatch;
 	}
 
+	/**
+	 * Get the database connection (read-only)
+	 * @return DatabaseBase
+	 */
+	protected function getDB() {
+		return $this->mDbSource->getDB();
+	}
+
 	/**
 	 * Returns the input array of integers with all values < 0 removed
 	 *
@@ -752,7 +930,7 @@ class ApiPageSet extends ApiQueryBase {
 		// bug 25734 API: possible issue with revids validation
 		// It seems with a load of revision rows, MySQL gets upset
 		// Remove any < 0 integers, as they can't be valid
-		foreach( $array as $i => $int ) {
+		foreach ( $array as $i => $int ) {
 			if ( $int < 0 ) {
 				unset( $array[$i] );
 			}
@@ -761,8 +939,8 @@ class ApiPageSet extends ApiQueryBase {
 		return $array;
 	}
 
-	public function getAllowedParams() {
-		return array(
+	public function getAllowedParams( $flags = 0 ) {
+		$result = array(
 			'titles' => array(
 				ApiBase::PARAM_ISMULTI => true
 			),
@@ -773,15 +951,48 @@ class ApiPageSet extends ApiQueryBase {
 			'revids' => array(
 				ApiBase::PARAM_TYPE => 'integer',
 				ApiBase::PARAM_ISMULTI => true
-			)
+			),
+			'redirects' => false,
+			'converttitles' => false,
 		);
+		if ( $this->mAllowGenerator ) {
+			$result['generator'] = array(
+				ApiBase::PARAM_TYPE => $this->getGenerators() );
+		}
+		return $result;
+	}
+
+	private static $generators = null;
+
+	/**
+	 * Get an array of all available generators
+	 * @return array
+	 */
+	private function getGenerators() {
+		if ( self::$generators === null ) {
+			$query = $this->mDbSource;
+			if ( !( $query instanceof ApiQuery ) ) {
+				// If the parent container of this pageset is not ApiQuery,
+				// we must create it to get module manager
+				$query = $this->getMain()->getModuleManager()->getModule( 'query' );
+			}
+			$gens = array_keys( $query->getGenerators() );
+			sort( $gens );
+			self::$generators = $gens;
+		}
+		return self::$generators;
 	}
 
 	public function getParamDescription() {
 		return array(
 			'titles' => 'A list of titles to work on',
 			'pageids' => 'A list of page IDs to work on',
-			'revids' => 'A list of revision IDs to work on'
+			'revids' => 'A list of revision IDs to work on',
+			'generator' => array( 'Get the list of pages to work on by executing the specified query module.',
+				'NOTE: generator parameter names must be prefixed with a \'g\', see examples' ),
+			'redirects' => 'Automatically resolve redirects',
+			'converttitles' => array( 'Convert titles to other variants if necessary. Only works if the wiki\'s content language supports variant conversion.',
+				'Languages that support variant conversion include ' . implode( ', ', LanguageConverter::$languagesWithVariants ) ),
 		);
 	}
 
@@ -789,6 +1000,7 @@ class ApiPageSet extends ApiQueryBase {
 		return array_merge( parent::getPossibleErrors(), array(
 			array( 'code' => 'multisource', 'info' => "Cannot use 'pageids' at the same time as 'dataSource'" ),
 			array( 'code' => 'multisource', 'info' => "Cannot use 'revids' at the same time as 'dataSource'" ),
+			array( 'code' => 'badgenerator', 'info' => 'Module $generatorName cannot be used as a generator' ),
 		) );
 	}
 }
diff --git a/includes/api/ApiParamInfo.php b/includes/api/ApiParamInfo.php
index c3112d04ad..6978a75536 100644
--- a/includes/api/ApiParamInfo.php
+++ b/includes/api/ApiParamInfo.php
@@ -125,7 +125,7 @@ class ApiParamInfo extends ApiBase {
 			$retval['generator'] = '';
 		}
 
-		$allowedParams = $obj->getFinalParams();
+		$allowedParams = $obj->getFinalParams( ApiBase::GET_VALUES_FOR_HELP );
 		if ( !is_array( $allowedParams ) ) {
 			return $retval;
 		}
diff --git a/includes/api/ApiPurge.php b/includes/api/ApiPurge.php
index fa888c9aaa..bd92077ce8 100644
--- a/includes/api/ApiPurge.php
+++ b/includes/api/ApiPurge.php
@@ -31,57 +31,59 @@
  */
 class ApiPurge extends ApiBase {
 
+	private $mPageSet;
+
+	/**
+	 * Add all items from $values into the result
+	 * @param $result array output
+	 * @param $values array values to add
+	 * @param $flag string the name of the boolean flag to mark this element
+	 * @param $name string if given, name of the value
+	 */
+	private static function addValues( array &$result, $values, $flag = null, $name = null ) {
+		foreach ( $values as $val ) {
+			if( $val instanceof Title ) {
+				$v = array();
+				ApiQueryBase::addTitleInfo( $v, $val );
+			} elseif( $name !== null ) {
+				$v = array( $name => $val );
+			} else {
+				$v = $val;
+			}
+			if( $flag !== null ) {
+				$v[$flag] = '';
+			}
+			$result[] = $v;
+		}
+	}
+
 	/**
 	 * Purges the cache of a page
 	 */
 	public function execute() {
-		$user = $this->getUser();
 		$params = $this->extractRequestParams();
-		if ( !$user->isAllowed( 'purge' ) && !$this->getMain()->isInternalMode() &&
-				!$this->getRequest()->wasPosted() ) {
-			$this->dieUsageMsg( array( 'mustbeposted', $this->getModuleName() ) );
-		}
 
 		$forceLinkUpdate = $params['forcelinkupdate'];
-		$pageSet = new ApiPageSet( $this );
+		$pageSet = $this->getPageSet();
 		$pageSet->execute();
 
 		$result = array();
-		foreach( $pageSet->getInvalidTitles() as $title ) {
+		self::addValues( $result, $pageSet->getInvalidTitles(), 'invalid', 'title' );
+		self::addValues( $result, $pageSet->getSpecialTitles(), 'special', 'title' );
+		self::addValues( $result, $pageSet->getMissingPageIDs(), 'missing', 'pageid' );
+		self::addValues( $result, $pageSet->getMissingRevisionIDs(), 'missing', 'revid' );
+		self::addValues( $result, $pageSet->getMissingTitles(), 'missing' );
+		self::addValues( $result, $pageSet->getInterwikiTitlesAsResult() );
+
+		foreach ( $pageSet->getGoodTitles() as $title ) {
 			$r = array();
-			$r['title'] = $title;
-			$r['invalid'] = '';
-			$result[] = $r;
-		}
-		foreach( $pageSet->getMissingPageIDs() as $p ) {
-			$page = array();
-			$page['pageid'] = $p;
-			$page['missing'] = '';
-			$result[] = $page;
-		}
-		foreach( $pageSet->getMissingRevisionIDs() as $r ) {
-			$rev = array();
-			$rev['revid'] = $r;
-			$rev['missing'] = '';
-			$result[] = $rev;
-		}
-
-		foreach ( $pageSet->getTitles() as $title ) {
-			$r = array();
-
 			ApiQueryBase::addTitleInfo( $r, $title );
-			if ( !$title->exists() ) {
-				$r['missing'] = '';
-				$result[] = $r;
-				continue;
-			}
-
 			$page = WikiPage::factory( $title );
 			$page->doPurge(); // Directly purge and skip the UI part of purge().
 			$r['purged'] = '';
 
-			if( $forceLinkUpdate ) {
-				if ( !$user->pingLimiter() ) {
+			if ( $forceLinkUpdate ) {
+				if ( !$this->getUser()->pingLimiter() ) {
 					global $wgEnableParserCache;
 
 					$popts = $page->makeParserOptions( 'canonical' );
@@ -112,24 +114,52 @@ class ApiPurge extends ApiBase {
 		$apiResult = $this->getResult();
 		$apiResult->setIndexedTagName( $result, 'page' );
 		$apiResult->addValue( null, $this->getModuleName(), $result );
+
+		$values = $pageSet->getNormalizedTitlesAsResult( $apiResult );
+		if ( $values ) {
+			$apiResult->addValue( null, 'normalized', $values );
+		}
+		$values = $pageSet->getConvertedTitlesAsResult( $apiResult );
+		if ( $values ) {
+			$apiResult->addValue( null, 'converted', $values );
+		}
+		$values = $pageSet->getRedirectTitlesAsResult( $apiResult );
+		if ( $values ) {
+			$apiResult->addValue( null, 'redirects', $values );
+		}
+	}
+
+	/**
+	 * Get a cached instance of an ApiPageSet object
+	 * @return ApiPageSet
+	 */
+	private function getPageSet() {
+		if ( !isset( $this->mPageSet ) ) {
+			$this->mPageSet = new ApiPageSet( $this );
+		}
+		return $this->mPageSet;
 	}
 
 	public function isWriteMode() {
 		return true;
 	}
 
-	public function getAllowedParams() {
-		$psModule = new ApiPageSet( $this );
-		return $psModule->getAllowedParams() + array(
-			'forcelinkupdate' => false,
-		);
+	public function mustBePosted() {
+		// Anonymous users are not allowed a non-POST request
+		return !$this->getUser()->isAllowed( 'purge' );
+	}
+
+	public function getAllowedParams( $flags = 0 ) {
+		$result = array( 'forcelinkupdate' => false );
+		if ( $flags ) {
+			$result += $this->getPageSet()->getFinalParams( $flags );
+		}
+		return $result;
 	}
 
 	public function getParamDescription() {
-		$psModule = new ApiPageSet( $this );
-		return $psModule->getParamDescription() + array(
-			'forcelinkupdate' => 'Update the links tables',
-		);
+		return $this->getPageSet()->getParamDescription()
+			+ array( 'forcelinkupdate' => 'Update the links tables' );
 	}
 
 	public function getResultProperties() {
@@ -153,9 +183,14 @@ class ApiPurge extends ApiBase {
 					ApiBase::PROP_NULLABLE => true
 				),
 				'invalid' => 'boolean',
+				'special' => 'boolean',
 				'missing' => 'boolean',
 				'purged' => 'boolean',
-				'linkupdate' => 'boolean'
+				'linkupdate' => 'boolean',
+				'iw' => array(
+					ApiBase::PROP_TYPE => 'string',
+					ApiBase::PROP_NULLABLE => true
+				),
 			)
 		);
 	}
@@ -167,10 +202,9 @@ class ApiPurge extends ApiBase {
 	}
 
 	public function getPossibleErrors() {
-		$psModule = new ApiPageSet( $this );
 		return array_merge(
 			parent::getPossibleErrors(),
-			$psModule->getPossibleErrors()
+			$this->getPageSet()->getPossibleErrors()
 		);
 	}
 
diff --git a/includes/api/ApiQuery.php b/includes/api/ApiQuery.php
index 35dd6954ae..619d1cae51 100644
--- a/includes/api/ApiQuery.php
+++ b/includes/api/ApiQuery.php
@@ -140,13 +140,11 @@ class ApiQuery extends ApiBase {
 	 */
 	private $mPageSet;
 
-	private $params, $redirects, $convertTitles, $iwUrl;
-	private $mSlaveDB = null;
+	private $params;
+	private $iwUrl;
 	private $mNamedDB = array();
 	private $mModuleMgr;
 
-	protected $mAllowedGenerators;
-
 	/**
 	 * @param $main ApiMain
 	 * @param $action string
@@ -171,7 +169,9 @@ class ApiQuery extends ApiBase {
 				$this->mQueryGenerators[$moduleName] = $moduleClass;
 			}
 		}
-		$this->mAllowedGenerators = array_keys( $this->mQueryGenerators );
+
+		// Create PageSet that will process titles/pageids/revids/generator
+		$this->mPageSet = new ApiPageSet( $this );
 	}
 
 	/**
@@ -182,19 +182,6 @@ class ApiQuery extends ApiBase {
 		return $this->mModuleMgr;
 	}
 
-	/**
-	 * Gets a default slave database connection object
-	 * @return DatabaseBase
-	 */
-	public function getDB() {
-		if ( !isset( $this->mSlaveDB ) ) {
-			$this->profileDBIn();
-			$this->mSlaveDB = wfGetDB( DB_SLAVE, 'api' );
-			$this->profileDBOut();
-		}
-		return $this->mSlaveDB;
-	}
-
 	/**
 	 * Get the query database connection with the given name.
 	 * If no such connection has been requested before, it will be created.
@@ -228,6 +215,7 @@ class ApiQuery extends ApiBase {
 	 * @return array array(modulename => classname)
 	 */
 	public function getModules() {
+		wfDeprecated( __METHOD__, '1.21' );
 		return $this->getModuleManager()->getNamesWithClasses();
 	}
 
@@ -276,34 +264,25 @@ class ApiQuery extends ApiBase {
 	 */
 	public function execute() {
 		$this->params = $this->extractRequestParams();
-		$this->redirects = $this->params['redirects'];
-		$this->convertTitles = $this->params['converttitles'];
 		$this->iwUrl = $this->params['iwurl'];
 
-		// Create PageSet
-		$this->mPageSet = new ApiPageSet( $this, $this->redirects, $this->convertTitles );
-
 		// Instantiate requested modules
 		$modules = array();
 		$this->instantiateModules( $modules, 'prop' );
 		$this->instantiateModules( $modules, 'list' );
 		$this->instantiateModules( $modules, 'meta' );
 
-		$cacheMode = 'public';
-
-		// If given, execute generator to substitute user supplied data with generated data.
-		if ( isset( $this->params['generator'] ) ) {
-			$generator = $this->newGenerator( $this->params['generator'] );
-			$params = $generator->extractRequestParams();
-			$cacheMode = $this->mergeCacheMode( $cacheMode,
-				$generator->getCacheMode( $params ) );
-			$this->executeGeneratorModule( $generator, $modules );
-		} else {
-			// Append custom fields and populate page/revision information
-			$this->addCustomFldsToPageSet( $modules, $this->mPageSet );
-			$this->mPageSet->execute();
+		// Query modules may optimize data requests through the $this->getPageSet()
+		// object by adding extra fields from the page table.
+		// This function will gather all the extra request fields from the modules.
+		foreach ( $modules as $module ) {
+			$module->requestExtraData( $this->mPageSet );
 		}
 
+		// Populate page/revision information
+		$this->mPageSet->execute();
+		$cacheMode = $this->mPageSet->getCacheMode();
+
 		// Record page information (title, namespace, if exists, etc)
 		$this->outputGeneralPageInfo();
 
@@ -347,23 +326,6 @@ class ApiQuery extends ApiBase {
 		return $cacheMode;
 	}
 
-	/**
-	 * Query modules may optimize data requests through the $this->getPageSet() object
-	 * by adding extra fields from the page table.
-	 * This function will gather all the extra request fields from the modules.
-	 * @param $modules array of module objects
-	 * @param $pageSet ApiPageSet
-	 */
-	private function addCustomFldsToPageSet( $modules, $pageSet ) {
-		// Query all requested modules.
-		/**
-		 * @var $module ApiQueryBase
-		 */
-		foreach ( $modules as $module ) {
-			$module->requestExtraData( $pageSet );
-		}
-	}
-
 	/**
 	 * Create instances of all modules requested by the client
 	 * @param $modules Array to append instantiated modules to
@@ -390,85 +352,25 @@ class ApiQuery extends ApiBase {
 		// more than 380K. The maximum revision size is in the megabyte range,
 		// and the maximum result size must be even higher than that.
 
-		// Title normalizations
-		$normValues = array();
-		foreach ( $pageSet->getNormalizedTitles() as $rawTitleStr => $titleStr ) {
-			$normValues[] = array(
-				'from' => $rawTitleStr,
-				'to' => $titleStr
-			);
+		$values = $pageSet->getNormalizedTitlesAsResult( $result );
+		if ( $values ) {
+			$result->addValue( 'query', 'normalized', $values );
 		}
-
-		if ( count( $normValues ) ) {
-			$result->setIndexedTagName( $normValues, 'n' );
-			$result->addValue( 'query', 'normalized', $normValues );
+		$values = $pageSet->getConvertedTitlesAsResult( $result );
+		if ( $values ) {
+			$result->addValue( 'query', 'converted', $values );
 		}
-
-		// Title conversions
-		$convValues = array();
-		foreach ( $pageSet->getConvertedTitles() as $rawTitleStr => $titleStr ) {
-			$convValues[] = array(
-				'from' => $rawTitleStr,
-				'to' => $titleStr
-			);
+		$values = $pageSet->getInterwikiTitlesAsResult( $result, $this->iwUrl );
+		if ( $values ) {
+			$result->addValue( 'query', 'interwiki', $values );
 		}
-
-		if ( count( $convValues ) ) {
-			$result->setIndexedTagName( $convValues, 'c' );
-			$result->addValue( 'query', 'converted', $convValues );
+		$values = $pageSet->getRedirectTitlesAsResult( $result );
+		if ( $values ) {
+			$result->addValue( 'query', 'redirects', $values );
 		}
-
-		// Interwiki titles
-		$intrwValues = array();
-		foreach ( $pageSet->getInterwikiTitles() as $rawTitleStr => $interwikiStr ) {
-			$item = array(
-				'title' => $rawTitleStr,
-				'iw' => $interwikiStr,
-			);
-			if ( $this->iwUrl ) {
-				$title = Title::newFromText( $rawTitleStr );
-				$item['url'] = wfExpandUrl( $title->getFullURL(), PROTO_CURRENT );
-			}
-			$intrwValues[] = $item;
-		}
-
-		if ( count( $intrwValues ) ) {
-			$result->setIndexedTagName( $intrwValues, 'i' );
-			$result->addValue( 'query', 'interwiki', $intrwValues );
-		}
-
-		// Show redirect information
-		$redirValues = array();
-		/**
-		 * @var $titleTo Title
-		 */
-		foreach ( $pageSet->getRedirectTitles() as $titleStrFrom => $titleTo ) {
-			$r = array(
-				'from' => strval( $titleStrFrom ),
-				'to' => $titleTo->getPrefixedText(),
-			);
-			if ( $titleTo->getFragment() !== '' ) {
-				$r['tofragment'] = $titleTo->getFragment();
-			}
-			$redirValues[] = $r;
-		}
-
-		if ( count( $redirValues ) ) {
-			$result->setIndexedTagName( $redirValues, 'r' );
-			$result->addValue( 'query', 'redirects', $redirValues );
-		}
-
-		// Missing revision elements
-		$missingRevIDs = $pageSet->getMissingRevisionIDs();
-		if ( count( $missingRevIDs ) ) {
-			$revids = array();
-			foreach ( $missingRevIDs as $revid ) {
-				$revids[$revid] = array(
-					'revid' => $revid
-				);
-			}
-			$result->setIndexedTagName( $revids, 'rev' );
-			$result->addValue( 'query', 'badrevids', $revids );
+		$values = $pageSet->getMissingRevisionIDsAsResult( $result );
+		if ( $values ) {
+			$result->addValue( 'query', 'badrevids', $values );
 		}
 
 		// Page elements
@@ -533,8 +435,8 @@ class ApiQuery extends ApiBase {
 	}
 
 	/**
-	 * @param  $pageSet ApiPageSet Pages to be exported
-	 * @param  $result ApiResult Result to output to
+	 * @param $pageSet ApiPageSet Pages to be exported
+	 * @param $result ApiResult Result to output to
 	 */
 	private function doExport( $pageSet, $result ) {
 		$exportTitles = array();
@@ -577,53 +479,8 @@ class ApiQuery extends ApiBase {
 		$result->enableSizeCheck();
 	}
 
-	/**
-	 * Create a generator object of the given type and return it
-	 * @param $generatorName string Module name
-	 * @return ApiQueryGeneratorBase
-	 */
-	public function newGenerator( $generatorName ) {
-		$generator = $this->mModuleMgr->getModule( $generatorName, null, true );
-		if ( $generator === null ) {
-			$this->dieUsage( "Unknown generator=$generatorName", 'badgenerator' );
-		}
-		if ( !$generator instanceof ApiQueryGeneratorBase ) {
-			$this->dieUsage( "Module $generatorName cannot be used as a generator", 'badgenerator' );
-		}
-		$generator->setGeneratorMode();
-		return $generator;
-	}
-
-	/**
-	 * For generator mode, execute generator, and use its output as new
-	 * ApiPageSet
-	 * @param $generator ApiQueryGeneratorBase Generator Module
-	 * @param $modules array of module objects
-	 */
-	protected function executeGeneratorModule( $generator, $modules ) {
-		// Generator results
-		$resultPageSet = new ApiPageSet( $this, $this->redirects, $this->convertTitles );
-
-		// Add any additional fields modules may need
-		$generator->requestExtraData( $this->mPageSet );
-		$this->addCustomFldsToPageSet( $modules, $resultPageSet );
-
-		// Populate page information with the original user input
-		$this->mPageSet->execute();
-
-		// populate resultPageSet with the generator output
-		$generator->profileIn();
-		$generator->executeGenerator( $resultPageSet );
-		wfRunHooks( 'APIQueryGeneratorAfterExecute', array( &$generator, &$resultPageSet ) );
-		$resultPageSet->finishPageSetGeneration();
-		$generator->profileOut();
-
-		// Swap the resulting pageset back in
-		$this->mPageSet = $resultPageSet;
-	}
-
-	public function getAllowedParams() {
-		return array(
+	public function getAllowedParams( $flags = 0 ) {
+		$result = array(
 			'prop' => array(
 				ApiBase::PARAM_ISMULTI => true,
 				ApiBase::PARAM_TYPE => $this->mModuleMgr->getNames( 'prop' )
@@ -636,16 +493,15 @@ class ApiQuery extends ApiBase {
 				ApiBase::PARAM_ISMULTI => true,
 				ApiBase::PARAM_TYPE => $this->mModuleMgr->getNames( 'meta' )
 			),
-			'generator' => array(
-				ApiBase::PARAM_TYPE => $this->mAllowedGenerators
-			),
-			'redirects' => false,
-			'converttitles' => false,
 			'indexpageids' => false,
 			'export' => false,
 			'exportnowrap' => false,
 			'iwurl' => false,
 		);
+		if( $flags ) {
+			$result += $this->getPageSet()->getFinalParams( $flags );
+		}
+		return $result;
 	}
 
 	/**
@@ -653,13 +509,13 @@ class ApiQuery extends ApiBase {
 	 * @return string
 	 */
 	public function makeHelpMsg() {
-		// Make sure the internal object is empty
-		// (just in case a sub-module decides to optimize during instantiation)
-		$this->mPageSet = null;
+
+		// Use parent to make default message for the query module
+		$msg = parent::makeHelpMsg();
 
 		$querySeparator = str_repeat( '--- ', 12 );
 		$moduleSeparator = str_repeat( '*** ', 14 );
-		$msg = "\n$querySeparator Query: Prop  $querySeparator\n\n";
+		$msg .= "\n$querySeparator Query: Prop  $querySeparator\n\n";
 		$msg .= $this->makeHelpMsgHelper( 'prop' );
 		$msg .= "\n$querySeparator Query: List  $querySeparator\n\n";
 		$msg .= $this->makeHelpMsgHelper( 'list' );
@@ -667,9 +523,6 @@ class ApiQuery extends ApiBase {
 		$msg .= $this->makeHelpMsgHelper( 'meta' );
 		$msg .= "\n\n$moduleSeparator Modules: continuation  $moduleSeparator\n\n";
 
-		// Use parent to make default message for the query module
-		$msg = parent::makeHelpMsg() . $msg;
-
 		return $msg;
 	}
 
@@ -703,29 +556,15 @@ class ApiQuery extends ApiBase {
 		return implode( "\n", $moduleDescriptions );
 	}
 
-	/**
-	 * Override to add extra parameters from PageSet
-	 * @return string
-	 */
-	public function makeHelpMsgParameters() {
-		$psModule = new ApiPageSet( $this );
-		return $psModule->makeHelpMsgParameters() . parent::makeHelpMsgParameters();
-	}
-
 	public function shouldCheckMaxlag() {
 		return true;
 	}
 
 	public function getParamDescription() {
-		return array(
+		return $this->getPageSet()->getParamDescription() + array(
 			'prop' => 'Which properties to get for the titles/revisions/pageids. Module help is available below',
 			'list' => 'Which lists to get. Module help is available below',
 			'meta' => 'Which metadata to get about the site. Module help is available below',
-			'generator' => array( 'Use the output of a list as the input for other prop/list/meta items',
-					'NOTE: generator parameter names must be prefixed with a \'g\', see examples' ),
-			'redirects' => 'Automatically resolve redirects',
-			'converttitles' => array( "Convert titles to other variants if necessary. Only works if the wiki's content language supports variant conversion.",
-					'Languages that support variant conversion include ' . implode( ', ', LanguageConverter::$languagesWithVariants ) ),
 			'indexpageids' => 'Include an additional pageids section listing all returned page IDs',
 			'export' => 'Export the current revisions of all given or generated pages',
 			'exportnowrap' => 'Return the export XML without wrapping it in an XML result (same format as Special:Export). Can only be used with export',
@@ -742,9 +581,10 @@ class ApiQuery extends ApiBase {
 	}
 
 	public function getPossibleErrors() {
-		return array_merge( parent::getPossibleErrors(), array(
-			array( 'code' => 'badgenerator', 'info' => 'Module $generatorName cannot be used as a generator' ),
-		) );
+		return array_merge(
+			parent::getPossibleErrors(),
+			$this->getPageSet()->getPossibleErrors()
+		);
 	}
 
 	public function getExamples() {
diff --git a/includes/api/ApiQueryAllImages.php b/includes/api/ApiQueryAllImages.php
index bbc527244b..b7abb54f29 100644
--- a/includes/api/ApiQueryAllImages.php
+++ b/includes/api/ApiQueryAllImages.php
@@ -41,7 +41,7 @@ class ApiQueryAllImages extends ApiQueryGeneratorBase {
 	}
 
 	/**
-	 * Override parent method to make sure to make sure the repo's DB is used
+	 * Override parent method to make sure the repo's DB is used
 	 * which may not necesarilly be the same as the local DB.
 	 *
 	 * TODO: allow querying non-local repos.
diff --git a/includes/api/ApiQueryBase.php b/includes/api/ApiQueryBase.php
index addcf074ca..59e665209e 100644
--- a/includes/api/ApiQueryBase.php
+++ b/includes/api/ApiQueryBase.php
@@ -393,8 +393,7 @@ abstract class ApiQueryBase extends ApiBase {
 	 */
 	protected function getDB() {
 		if ( is_null( $this->mDb ) ) {
-			$apiQuery = $this->getQuery();
-			$this->mDb = $apiQuery->getDB();
+			$this->mDb = $this->getQuery()->getDB();
 		}
 		return $this->mDb;
 	}
@@ -585,24 +584,32 @@ abstract class ApiQueryBase extends ApiBase {
  */
 abstract class ApiQueryGeneratorBase extends ApiQueryBase {
 
-	private $mIsGenerator;
+	private $mGeneratorPageSet = null;
 
 	/**
-	 * @param $query ApiBase
-	 * @param $moduleName string
-	 * @param $paramPrefix string
+	 * Switch this module to generator mode. By default, generator mode is
+	 * switched off and the module acts like a normal query module.
+	 * @since 1.21 requires pageset parameter
+	 * @param $generatorPageSet ApiPageSet object that the module will get
+	 *        by calling getPageSet() when in generator mode.
 	 */
-	public function __construct( $query, $moduleName, $paramPrefix = '' ) {
-		parent::__construct( $query, $moduleName, $paramPrefix );
-		$this->mIsGenerator = false;
+	public function setGeneratorMode( ApiPageSet $generatorPageSet ) {
+		if ( $generatorPageSet === null ) {
+			ApiBase::dieDebug( __METHOD__, 'Required parameter missing - $generatorPageSet' );
+		}
+		$this->mGeneratorPageSet = $generatorPageSet;
 	}
 
 	/**
-	 * Switch this module to generator mode. By default, generator mode is
-	 * switched off and the module acts like a normal query module.
+	 * Get the PageSet object to work on.
+	 * If this module is generator, the pageSet object is different from other module's
+	 * @return ApiPageSet
 	 */
-	public function setGeneratorMode() {
-		$this->mIsGenerator = true;
+	protected function getPageSet() {
+		if ( $this->mGeneratorPageSet !== null ) {
+			return $this->mGeneratorPageSet;
+		}
+		return parent::getPageSet();
 	}
 
 	/**
@@ -611,7 +618,7 @@ abstract class ApiQueryGeneratorBase extends ApiQueryBase {
 	 * @return string Prefixed parameter name
 	 */
 	public function encodeParamName( $paramName ) {
-		if ( $this->mIsGenerator ) {
+		if ( $this->mGeneratorPageSet !== null ) {
 			return 'g' . parent::encodeParamName( $paramName );
 		} else {
 			return parent::encodeParamName( $paramName );
diff --git a/includes/api/ApiSetNotificationTimestamp.php b/includes/api/ApiSetNotificationTimestamp.php
index 7a47a0ce88..3f5ebfe85a 100644
--- a/includes/api/ApiSetNotificationTimestamp.php
+++ b/includes/api/ApiSetNotificationTimestamp.php
@@ -31,6 +31,8 @@
  */
 class ApiSetNotificationTimestamp extends ApiBase {
 
+	private $mPageSet;
+
 	public function execute() {
 		$user = $this->getUser();
 
@@ -41,7 +43,7 @@ class ApiSetNotificationTimestamp extends ApiBase {
 		$params = $this->extractRequestParams();
 		$this->requireMaxOneParameter( $params, 'timestamp', 'torevid', 'newerthanrevid' );
 
-		$pageSet = new ApiPageSet( $this );
+		$pageSet = $this->getPageSet();
 		$args = array_merge( array( $params, 'entirewatchlist' ), array_keys( $pageSet->getAllowedParams() ) );
 		call_user_func_array( array( $this, 'requireOnlyOneParameter' ), $args );
 
@@ -92,20 +94,20 @@ class ApiSetNotificationTimestamp extends ApiBase {
 			$result['notificationtimestamp'] = ( is_null( $timestamp ) ? '' : wfTimestamp( TS_ISO_8601, $timestamp ) );
 		} else {
 			// First, log the invalid titles
-			foreach( $pageSet->getInvalidTitles() as $title ) {
+			foreach ( $pageSet->getInvalidTitles() as $title ) {
 				$r = array();
 				$r['title'] = $title;
 				$r['invalid'] = '';
 				$result[] = $r;
 			}
-			foreach( $pageSet->getMissingPageIDs() as $p ) {
+			foreach ( $pageSet->getMissingPageIDs() as $p ) {
 				$page = array();
 				$page['pageid'] = $p;
 				$page['missing'] = '';
 				$page['notwatched'] = '';
 				$result[] = $page;
 			}
-			foreach( $pageSet->getMissingRevisionIDs() as $r ) {
+			foreach ( $pageSet->getMissingRevisionIDs() as $r ) {
 				$rev = array();
 				$rev['revid'] = $r;
 				$rev['missing'] = '';
@@ -157,6 +159,17 @@ class ApiSetNotificationTimestamp extends ApiBase {
 		$apiResult->addValue( null, $this->getModuleName(), $result );
 	}
 
+	/**
+	 * Get a cached instance of an ApiPageSet object
+	 * @return ApiPageSet
+	 */
+	private function getPageSet() {
+		if ( !isset( $this->mPageSet ) ) {
+			$this->mPageSet = new ApiPageSet( $this );
+		}
+		return $this->mPageSet;
+	}
+
 	public function mustBePosted() {
 		return true;
 	}
@@ -173,9 +186,8 @@ class ApiSetNotificationTimestamp extends ApiBase {
 		return '';
 	}
 
-	public function getAllowedParams() {
-		$psModule = new ApiPageSet( $this );
-		return $psModule->getAllowedParams() + array(
+	public function getAllowedParams( $flags = 0 ) {
+		$result = array(
 			'entirewatchlist' => array(
 				ApiBase::PARAM_TYPE => 'boolean'
 			),
@@ -190,11 +202,15 @@ class ApiSetNotificationTimestamp extends ApiBase {
 				ApiBase::PARAM_TYPE => 'integer'
 			),
 		);
+		if ( $flags ) {
+			$result += $this->getPageSet()->getFinalParams( $flags );
+		}
+		return $result;
+
 	}
 
 	public function getParamDescription() {
-		$psModule = new ApiPageSet( $this );
-		return $psModule->getParamDescription() + array(
+		return $this->getPageSet()->getParamDescription() + array(
 			'entirewatchlist' => 'Work on all watched pages',
 			'timestamp' => 'Timestamp to which to set the notification timestamp',
 			'torevid' => 'Revision to set the notification timestamp to (one page only)',
@@ -249,12 +265,14 @@ class ApiSetNotificationTimestamp extends ApiBase {
 	}
 
 	public function getPossibleErrors() {
-		$psModule = new ApiPageSet( $this );
+		$ps = $this->getPageSet();
 		return array_merge(
 			parent::getPossibleErrors(),
-			$psModule->getPossibleErrors(),
-			$this->getRequireMaxOneParameterErrorMessages( array( 'timestamp', 'torevid', 'newerthanrevid' ) ),
-			$this->getRequireOnlyOneParameterErrorMessages( array_merge( array( 'entirewatchlist' ), array_keys( $psModule->getAllowedParams() ) ) ),
+			$ps->getPossibleErrors(),
+			$this->getRequireMaxOneParameterErrorMessages(
+				array( 'timestamp', 'torevid', 'newerthanrevid' ) ),
+			$this->getRequireOnlyOneParameterErrorMessages(
+				array_merge( array( 'entirewatchlist' ), array_keys( $ps->getFinalParams() ) ) ),
 			array(
 				array( 'code' => 'notloggedin', 'info' => 'Anonymous users cannot use watchlist change notifications' ),
 				array( 'code' => 'multpages', 'info' => 'torevid may only be used with a single page' ),
diff --git a/tests/phpunit/includes/api/ApiGeneratorTest.php b/tests/phpunit/includes/api/ApiGeneratorTest.php
index e5a871726f..445969bde8 100644
--- a/tests/phpunit/includes/api/ApiGeneratorTest.php
+++ b/tests/phpunit/includes/api/ApiGeneratorTest.php
@@ -39,7 +39,7 @@ class ApiGeneratorTest extends MediaWikiTestCase {
 	 */
 	public function provideApiquerygeneratorbaseChilds() {
 		$cases = array();
-		$modules = $this->getApiQuery()->getModules();
+		$modules = $this->getApiQuery()->getModuleManager()->getNamesWithClasses();
 		foreach( $modules as $moduleName => $moduleClass ) {
 			if( !is_subclass_of( $moduleClass, 'ApiQueryGeneratorBase' ) ) {
 				continue;
@@ -55,7 +55,7 @@ class ApiGeneratorTest extends MediaWikiTestCase {
 	public function testGeneratorsAreApiquerygeneratorbaseSubclasses(
 		$generatorName, $generatorClass
 	) {
-		$modules = $this->getApiQuery()->getModules();
+		$modules = $this->getApiQuery()->getModuleManager()->getNamesWithClasses();
 		$this->assertArrayHasKey( $generatorName, $modules,
 			"Class '$generatorClass' of generator '$generatorName' must be a subclass of 'ApiQueryGeneratorBase'. Listed either in ApiQuery::\$mQueryGenerators or in \$wgAPIGeneratorModules."
 		);
diff --git a/tests/phpunit/includes/api/PrefixUniquenessTest.php b/tests/phpunit/includes/api/PrefixUniquenessTest.php
index 3bacb054c4..d9be85e320 100644
--- a/tests/phpunit/includes/api/PrefixUniquenessTest.php
+++ b/tests/phpunit/includes/api/PrefixUniquenessTest.php
@@ -9,7 +9,7 @@ class PrefixUniquenessTest extends MediaWikiTestCase {
 	public function testPrefixes() {
 		$main = new ApiMain( new FauxRequest() );
 		$query = new ApiQuery( $main, 'foo', 'bar' );
-		$modules = $query->getModules();
+		$modules = $query->getModuleManager()->getNamesWithClasses();
 		$prefixes = array();
 
 		foreach ( $modules as $name => $class ) {
-- 
2.20.1