From 8f4f9404ce7700f4776bf93b3bf0ed5578a7ac5f Mon Sep 17 00:00:00 2001
From: Brian Wolff <bawolff+wn@gmail.com>
Date: Sun, 20 Oct 2013 17:48:19 -0300
Subject: [PATCH] Cache page content language in Title object

During the parsing process, $title->getPageLanguage() gets called
a large number of times for the same title. Apparently the value
can vary by user, but it should be safe to cache for the current
request (I believe).

On [[Commons:Commons:Featured_picture_candidates/Log/October_2013]],
it appears that this method is called 5118 times, and represents
20.58% (11.77 seconds) of the time to render the page.

Also checks if $wgLanguageCode has been changed, since Title
object are cached during a request, and the unit tests seem
to change $wgLanguageCode/$wgContLang while still using
the Title cache.

Bug: 55952
Change-Id: I84b2d86c7bcb32997acff47cfea0f789b5b960a6
---
 includes/Title.php | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/includes/Title.php b/includes/Title.php
index 56e9b44cc5..3418fa203d 100644
--- a/includes/Title.php
+++ b/includes/Title.php
@@ -86,6 +86,7 @@ class Title {
 	var $mRedirect = null;            // /< Is the article at this title a redirect?
 	var $mNotificationTimestamp = array(); // /< Associative array of user ID -> timestamp/false
 	var $mHasSubpage;                 // /< Whether a page has any subpages
+	private $mPageLanguage = false;   // /< The (string) language code of the page's language and content code.
 	// @}
 
 	/**
@@ -3110,6 +3111,7 @@ class Title {
 		$this->mLatestID = false;
 		$this->mContentModel = false;
 		$this->mEstimateRevisions = null;
+		$this->mPageLanguage = false;
 	}
 
 	/**
@@ -4808,18 +4810,26 @@ class Title {
 	 * @return Language
 	 */
 	public function getPageLanguage() {
-		global $wgLang;
+		global $wgLang, $wgLanguageCode;
+		wfProfileIn( __METHOD__ );
 		if ( $this->isSpecialPage() ) {
 			// special pages are in the user language
+			wfProfileOut( __METHOD__ );
 			return $wgLang;
 		}
 
-		//TODO: use the LinkCache to cache this! Note that this may depend on user settings, so the cache should be only per-request.
-		//NOTE: ContentHandler::getPageLanguage() may need to load the content to determine the page language!
-		$contentHandler = ContentHandler::getForTitle( $this );
-		$pageLang = $contentHandler->getPageLanguage( $this );
-
-		return wfGetLangObj( $pageLang );
+		if ( !$this->mPageLanguage || $this->mPageLanguage[1] !== $wgLanguageCode ) {
+			// Note that this may depend on user settings, so the cache should be only per-request.
+			// NOTE: ContentHandler::getPageLanguage() may need to load the content to determine the page language!
+			// Checking $wgLanguageCode hasn't changed for the benefit of unit tests.
+			$contentHandler = ContentHandler::getForTitle( $this );
+			$langObj = wfGetLangObj( $contentHandler->getPageLanguage( $this ) );
+			$this->mPageLanguage = array( $langObj->getCode(), $wgLanguageCode );
+		} else {
+			$langObj =  wfGetLangObj( $this->mPageLanguage[0] );
+		}
+		wfProfileOut( __METHOD__ );
+		return $langObj;
 	}
 
 	/**
-- 
2.20.1