From 9750150c2e2841af6f142b7e9282d82e188b9e69 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 24 Sep 2013 13:55:29 -0700
Subject: [PATCH] Reduce chance for parser cache race conditions

* Move cache time definition to happen before parse so it is less likely
  to override the cache with a stale value and a high cache timestamp.

bug: 46014
Change-Id: I021d27885ac260d89232ff11ec3cccf976e44f0f
---
 includes/WikiPage.php           |  6 +++++-
 includes/parser/ParserCache.php | 14 +++++++-------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/includes/WikiPage.php b/includes/WikiPage.php
index bfa9956e0c..8ea8e354ad 100644
--- a/includes/WikiPage.php
+++ b/includes/WikiPage.php
@@ -3510,6 +3510,9 @@ class PoolWorkArticleView extends PoolCounterWork {
 			return false;
 		}
 
+		// Reduce effects of race conditions for slow parses (bug 46014)
+		$cacheTime = wfTimestampNow();
+
 		$time = - microtime( true );
 		$this->parserOutput = $content->getParserOutput( $this->page->getTitle(), $this->revid, $this->parserOptions );
 		$time += microtime( true );
@@ -3521,7 +3524,8 @@ class PoolWorkArticleView extends PoolCounterWork {
 		}
 
 		if ( $this->cacheable && $this->parserOutput->isCacheable() ) {
-			ParserCache::singleton()->save( $this->parserOutput, $this->page, $this->parserOptions );
+			ParserCache::singleton()->save(
+				$this->parserOutput, $this->page, $this->parserOptions, $cacheTime );
 		}
 
 		// Make sure file cache is not used on uncacheable content.
diff --git a/includes/parser/ParserCache.php b/includes/parser/ParserCache.php
index 7c5eeb4a8f..7053f134c6 100644
--- a/includes/parser/ParserCache.php
+++ b/includes/parser/ParserCache.php
@@ -223,19 +223,19 @@ class ParserCache {
 	 * @param $parserOutput ParserOutput
 	 * @param $article Article
 	 * @param $popts ParserOptions
+	 * @param $cacheTime Time when the cache was generated
 	 */
-	public function save( $parserOutput, $article, $popts ) {
+	public function save( $parserOutput, $article, $popts, $cacheTime = null ) {
 		$expire = $parserOutput->getCacheExpiry();
-
 		if ( $expire > 0 ) {
-			$now = wfTimestampNow();
+			$cacheTime = $cacheTime ?: wfTimestampNow();
 
 			$optionsKey = new CacheTime;
 			$optionsKey->mUsedOptions = $parserOutput->getUsedOptions();
 			$optionsKey->updateCacheExpiry( $expire );
 
-			$optionsKey->setCacheTime( $now );
-			$parserOutput->setCacheTime( $now );
+			$optionsKey->setCacheTime( $cacheTime );
+			$parserOutput->setCacheTime( $cacheTime );
 
 			$optionsKey->setContainsOldMagic( $parserOutput->containsOldMagic() );
 
@@ -245,8 +245,8 @@ class ParserCache {
 			// Save the timestamp so that we don't have to load the revision row on view
 			$parserOutput->setTimestamp( $article->getTimestamp() );
 
-			$parserOutput->mText .= "\n<!-- Saved in parser cache with key $parserOutputKey and timestamp $now -->\n";
-			wfDebug( "Saved in parser cache with key $parserOutputKey and timestamp $now\n" );
+			$parserOutput->mText .= "\n<!-- Saved in parser cache with key $parserOutputKey and timestamp $cacheTime\n -->\n";
+			wfDebug( "Saved in parser cache with key $parserOutputKey and timestamp $cacheTime\n" );
 
 			// Save the parser output
 			$this->mMemc->set( $parserOutputKey, $parserOutput, $expire );
-- 
2.20.1