From 38f65afecfcb961577d9fcd7478d4f9d23da413d Mon Sep 17 00:00:00 2001
From: Sara Arjona <sara@moodle.com>
Date: Fri, 14 Dec 2018 13:29:36 +0100
Subject: [PATCH] MDL-63677 core_user: Avoid redirection during signup

Purge cache just for the current user to avoid redirection when 2
simultaneous users try to sign up at the same time and some policy
has to be agreed.
The 'createduser' invalidation event has been removed also because
is not used any more.
Thanks John Azinheira for spotting it!
---
 lib/db/caches.php | 5 +----
 user/lib.php      | 5 +++--
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/db/caches.php b/lib/db/caches.php
index cd69bbccd11..38038eadb80 100644
--- a/lib/db/caches.php
+++ b/lib/db/caches.php
@@ -382,9 +382,6 @@ $definitions = array(
         'mode' => cache_store::MODE_SESSION,
         'simplekeys' => true,
         'simpledata' => true,
-        'ttl' => 1800,
-        'invalidationevents' => array(
-            'createduser',
-        )
+        'ttl' => 1800
     ),
 );
diff --git a/user/lib.php b/user/lib.php
index 7bb4f5f4070..ea1c1cb829a 100644
--- a/user/lib.php
+++ b/user/lib.php
@@ -126,8 +126,9 @@ function user_create_user($user, $updatepassword = true, $triggerevent = true) {
         \core\event\user_created::create_from_userid($newuserid)->trigger();
     }
 
-    // Purge the associated caches.
-    cache_helper::purge_by_event('createduser');
+    // Purge the associated caches for the current user only.
+    $presignupcache = \cache::make('core', 'presignup');
+    $presignupcache->purge_current_user();
 
     return $newuserid;
 }