From: Aaron Schulz <aschulz@wikimedia.org>
Date: Fri, 8 Jun 2018 20:43:03 +0000 (-0700)
Subject: Make interwiki transclusion use the WAN cache
X-Git-Tag: 1.34.0-rc.0~4289^2
X-Git-Url: https://git.cyclocoop.org/%7B%24www_url%7Dadmin/compta/banques/%7B%7B%20url_for%28%27admin_users%27%29%20%7D%7D?a=commitdiff_plain;h=6504e230743da300795304f174fe1d8fccd27175;p=lhc%2Fweb%2Fwiklou.git

Make interwiki transclusion use the WAN cache

This means that now:
* Entries actually get deleted when expired
* The transclusion cache is shared across wikis
* Large blobs that do not fit in cache no longer cause DB errors
* DB writes are not triggered on GET requests
* Keys are hashed and no longer need to be so restrictive

Also, add a "check key" based purge system and process cache the
text/html values similar to how regular revision text is cached.

Bug: T189702
Change-Id: I8ac12b53c02bb26857175dd5a4af29d49e03dc33
---

diff --git a/includes/page/WikiPage.php b/includes/page/WikiPage.php
index a1b2e574d1..e1b37c0961 100644
--- a/includes/page/WikiPage.php
+++ b/includes/page/WikiPage.php
@@ -3152,6 +3152,9 @@ class WikiPage implements Page, IDBAccessObject {
 
 		// Image redirects
 		RepoGroup::singleton()->getLocalRepo()->invalidateImageRedirect( $title );
+
+		// Purge cross-wiki cache entities referencing this page
+		self::purgeInterwikiCheckKey( $title );
 	}
 
 	/**
@@ -3190,14 +3193,41 @@ class WikiPage implements Page, IDBAccessObject {
 		// Clear file cache for this page only
 		HTMLFileCache::clearFileCache( $title );
 
+		// Purge ?action=info cache
 		$revid = $revision ? $revision->getId() : null;
 		DeferredUpdates::addCallableUpdate( function () use ( $title, $revid ) {
 			InfoAction::invalidateCache( $title, $revid );
 		} );
+
+		// Purge cross-wiki cache entities referencing this page
+		self::purgeInterwikiCheckKey( $title );
 	}
 
 	/**#@-*/
 
+	/**
+	 * Purge the check key for cross-wiki cache entries referencing this page
+	 *
+	 * @param Title $title
+	 */
+	private static function purgeInterwikiCheckKey( Title $title ) {
+		global $wgEnableScaryTranscluding;
+
+		if ( !$wgEnableScaryTranscluding ) {
+			return; // @todo: perhaps this wiki is only used as a *source* for content?
+		}
+
+		DeferredUpdates::addCallableUpdate( function () use ( $title ) {
+			$cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
+			$cache->resetCheckKey(
+				// Do not include the namespace since there can be multiple aliases to it
+				// due to different namespace text definitions on different wikis. This only
+				// means that some cache invalidations happen that are not strictly needed.
+				$cache->makeGlobalKey( 'interwiki-page', wfWikiID(), $title->getDBkey() )
+			);
+		} );
+	}
+
 	/**
 	 * Returns a list of categories this page is a member of.
 	 * Results will include hidden categories
diff --git a/includes/parser/Parser.php b/includes/parser/Parser.php
index 12d899bc34..3920e7bce6 100644
--- a/includes/parser/Parser.php
+++ b/includes/parser/Parser.php
@@ -3739,57 +3739,68 @@ class Parser {
 	 * Transclude an interwiki link.
 	 *
 	 * @param Title $title
-	 * @param string $action
+	 * @param string $action Usually one of (raw, render)
 	 *
 	 * @return string
 	 */
 	public function interwikiTransclude( $title, $action ) {
-		global $wgEnableScaryTranscluding;
+		global $wgEnableScaryTranscluding, $wgTranscludeCacheExpiry;
 
 		if ( !$wgEnableScaryTranscluding ) {
 			return wfMessage( 'scarytranscludedisabled' )->inContentLanguage()->text();
 		}
 
 		$url = $title->getFullURL( [ 'action' => $action ] );
-
-		if ( strlen( $url ) > 255 ) {
+		if ( strlen( $url ) > 1024 ) {
 			return wfMessage( 'scarytranscludetoolong' )->inContentLanguage()->text();
 		}
-		return $this->fetchScaryTemplateMaybeFromCache( $url );
-	}
 
-	/**
-	 * @param string $url
-	 * @return mixed|string
-	 */
-	public function fetchScaryTemplateMaybeFromCache( $url ) {
-		global $wgTranscludeCacheExpiry;
-		$dbr = wfGetDB( DB_REPLICA );
-		$tsCond = $dbr->timestamp( time() - $wgTranscludeCacheExpiry );
-		$obj = $dbr->selectRow( 'transcache', [ 'tc_time', 'tc_contents' ],
-				[ 'tc_url' => $url, "tc_time >= " . $dbr->addQuotes( $tsCond ) ] );
-		if ( $obj ) {
-			return $obj->tc_contents;
-		}
-
-		$req = MWHttpRequest::factory( $url, [], __METHOD__ );
-		$status = $req->execute(); // Status object
-		if ( $status->isOK() ) {
-			$text = $req->getContent();
-		} elseif ( $req->getStatus() != 200 ) {
+		$wikiId = $title->getTransWikiID(); // remote wiki ID or false
+
+		$fname = __METHOD__;
+		$cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
+
+		$data = $cache->getWithSetCallback(
+			$cache->makeGlobalKey(
+				'interwiki-transclude',
+				( $wikiId !== false ) ? $wikiId : 'external',
+				sha1( $url )
+			),
+			$wgTranscludeCacheExpiry,
+			function ( $oldValue, &$ttl ) use ( $url, $fname, $cache ) {
+				$req = MWHttpRequest::factory( $url, [], $fname );
+
+				$status = $req->execute(); // Status object
+				if ( !$status->isOK() ) {
+					$ttl = $cache::TTL_UNCACHEABLE;
+				} elseif ( $req->getResponseHeader( 'X-Database-Lagged' ) !== null ) {
+					$ttl = min( $cache::TTL_LAGGED, $ttl );
+				}
+
+				return [
+					'text' => $status->isOK() ? $req->getContent() : null,
+					'code' => $req->getStatus()
+				];
+			},
+			[
+				'checkKeys' => ( $wikiId !== false )
+					? [ $cache->makeGlobalKey( 'interwiki-page', $wikiId, $title->getDBkey() ) ]
+					: [],
+				'pcGroup' => 'interwiki-transclude:5',
+				'pcTTL' => $cache::TTL_PROC_LONG
+			]
+		);
+
+		if ( is_string( $data['text'] ) ) {
+			$text = $data['text'];
+		} elseif ( $data['code'] != 200 ) {
 			// Though we failed to fetch the content, this status is useless.
-			return wfMessage( 'scarytranscludefailed-httpstatus' )
-				->params( $url, $req->getStatus() /* HTTP status */ )->inContentLanguage()->text();
+			$text = wfMessage( 'scarytranscludefailed-httpstatus' )
+				->params( $url, $data['code'] )->inContentLanguage()->text();
 		} else {
-			return wfMessage( 'scarytranscludefailed', $url )->inContentLanguage()->text();
+			$text = wfMessage( 'scarytranscludefailed', $url )->inContentLanguage()->text();
 		}
 
-		$dbw = wfGetDB( DB_MASTER );
-		$dbw->replace( 'transcache', [ 'tc_url' ], [
-			'tc_url' => $url,
-			'tc_time' => $dbw->timestamp( time() ),
-			'tc_contents' => $text
-		] );
 		return $text;
 	}