From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 21 Nov 2017 02:58:05 +0000 (-0800)
Subject: Avoid blocking locks during API edit stash generation
X-Git-Tag: 1.31.0-rc.0~1421^2
X-Git-Url: https://git.heureux-cyclage.org/?p=lhc%2Fweb%2Fwiklou.git;a=commitdiff_plain;h=6fb6fc9dc2170c75b35ede414d4049b6925b177a

Avoid blocking locks during API edit stash generation

Bug: T180793
Change-Id: Ibc29a20329113c3ee54fd48cfe86ca8251e8098d
---

diff --git a/includes/api/ApiStashEdit.php b/includes/api/ApiStashEdit.php
index 4bd6a3fb6f..b4b9321787 100644
--- a/includes/api/ApiStashEdit.php
+++ b/includes/api/ApiStashEdit.php
@@ -181,9 +181,14 @@ class ApiStashEdit extends ApiBase {
 		$title = $page->getTitle();
 		$key = self::getStashKey( $title, self::getContentHash( $content ), $user );
 
-		// Use the master DB for fast blocking locks
+		// Use the master DB to allow for fast blocking locks on the "save path" where this
+		// value might actually be used to complete a page edit. If the edit submission request
+		// happens before this edit stash requests finishes, then the submission will block until
+		// the stash request finishes parsing. For the lock acquisition below, there is not much
+		// need to duplicate parsing of the same content/user/summary bundle, so try to avoid
+		// blocking at all here.
 		$dbw = wfGetDB( DB_MASTER );
-		if ( !$dbw->lock( $key, __METHOD__, 1 ) ) {
+		if ( !$dbw->lock( $key, __METHOD__, 0 ) ) {
 			// De-duplicate requests on the same key
 			return self::ERROR_BUSY;
 		}