From 8a57b865a216360a55f5f96e098aae7715fd9580 Mon Sep 17 00:00:00 2001
From: umherirrender <umherirrender_de.wp@web.de>
Date: Fri, 7 Nov 2014 17:28:56 +0100
Subject: [PATCH] Add batch lookup for user groups on Special:ListUsers

At the moment for each user on the list a new user object is created and
than the getGroups method is called, which fully init the user object,
which is done in 3 queries (user table, user_properties and
user_groups).
Removed the user object with one query for all the userids and cache the
result.

Also added the group page to the LinkBatch, because now the necessary
pages can be determined easily.

Change-Id: I4a945f83ad28edf5cc040139943cf743cb3d133c
---
 includes/specials/SpecialListusers.php | 46 +++++++++++++++++++++++---
 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/includes/specials/SpecialListusers.php b/includes/specials/SpecialListusers.php
index 68c5346467..7669b5cc97 100644
--- a/includes/specials/SpecialListusers.php
+++ b/includes/specials/SpecialListusers.php
@@ -34,6 +34,11 @@
  */
 class UsersPager extends AlphabeticPager {
 
+	/**
+	 * @var array A array with user ids as key and a array of groups as value
+	 */
+	private $userGroupCache;
+
 	/**
 	 * @param IContextSource $context
 	 * @param array $par (Default null)
@@ -176,7 +181,7 @@ class UsersPager extends AlphabeticPager {
 		$lang = $this->getLanguage();
 
 		$groups = '';
-		$groups_list = self::getGroups( $row->user_id );
+		$groups_list = self::getGroups( intval( $row->user_id ), $this->userGroupCache );
 
 		if ( !$this->including && count( $groups_list ) > 0 ) {
 			$list = array();
@@ -218,11 +223,38 @@ class UsersPager extends AlphabeticPager {
 
 	function doBatchLookups() {
 		$batch = new LinkBatch();
+		$userIds = array();
 		# Give some pointers to make user links
 		foreach ( $this->mResult as $row ) {
 			$batch->add( NS_USER, $row->user_name );
 			$batch->add( NS_USER_TALK, $row->user_name );
+			$userIds[] = $row->user_id;
+		}
+
+		// Lookup groups for all the users
+		$dbr = wfGetDB( DB_SLAVE );
+		$groupRes = $dbr->select(
+			'user_groups',
+			array( 'ug_user', 'ug_group' ),
+			array( 'ug_user' => $userIds ),
+			__METHOD__
+		);
+		$cache = array();
+		$groups = array();
+		foreach ( $groupRes as $row ) {
+			$cache[intval( $row->ug_user )][] = $row->ug_group;
+			$groups[$row->ug_group] = true;
 		}
+		$this->userGroupCache = $cache;
+
+		// Add page of groups to link batch
+		foreach( $groups as $group => $unused ) {
+			$groupPage = User::getGroupPage( $group );
+			if ( $groupPage ) {
+				$batch->addObj( $groupPage );
+			}
+		}
+
 		$batch->execute();
 		$this->mResult->rewind();
 	}
@@ -331,11 +363,17 @@ class UsersPager extends AlphabeticPager {
 	 * Get a list of groups the specified user belongs to
 	 *
 	 * @param int $uid User id
+	 * @param array|null $cache
 	 * @return array
 	 */
-	protected static function getGroups( $uid ) {
-		$user = User::newFromId( $uid );
-		$groups = array_diff( $user->getEffectiveGroups(), User::getImplicitGroups() );
+	protected static function getGroups( $uid, $cache = null ) {
+		if ( $cache === null ) {
+			$user = User::newFromId( $uid );
+			$effectiveGroups = $user->getEffectiveGroups();
+		} else {
+			$effectiveGroups = isset( $cache[$uid] ) ? $cache[$uid] : array();
+		}
+		$groups = array_diff( $effectiveGroups, User::getImplicitGroups() );
 
 		return $groups;
 	}
-- 
2.20.1