From 9e50d6e999d02b4f8f0e90d6c5d93a866d0b1904 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Wed, 15 Apr 2015 20:34:51 -0700
Subject: [PATCH] Try to reduce stale cache updates in User::saveSettings()

Bug: T95839
Change-Id: I4dc87697448b833ea575cbb3e05c92c7160d03f9
---
 includes/User.php | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/includes/User.php b/includes/User.php
index f862953767..59d5c03cf8 100644
--- a/includes/User.php
+++ b/includes/User.php
@@ -3647,6 +3647,14 @@ class User implements IDBAccessObject {
 		Hooks::run( 'UserSaveSettings', array( $this ) );
 		$this->clearSharedCache();
 		$this->getUserPage()->invalidateCache();
+
+		// T95839: clear the cache again post-commit to reduce race conditions
+		// where stale values are written back to the cache by other threads.
+		// Note: this *still* doesn't deal with REPEATABLE-READ snapshot lag...
+		$that = $this;
+		$dbw->onTransactionIdle( function() use ( $that ) {
+			$that->clearSharedCache();
+		} );
 	}
 
 	/**
-- 
2.20.1