From 9c5c08859d8d728da8c5829cf993f4fb308ab1cf Mon Sep 17 00:00:00 2001
From: Gusted <postmaster@gusted.xyz>
Date: Mon, 12 Aug 2024 15:31:43 +0200
Subject: [PATCH] [BUG] Make logout event non-blocking

- When people click on the logout button, a event is sent to all
browser tabs (actually to a shared worker) to notify them of this
logout. This is done in a blocking fashion, to ensure every registered
channel (which realistically should be one for every user because of the
shared worker) for a user receives this message. While doing this, it
locks the mutex for the eventsource module.
- Codeberg is currently observing a deadlock that's caused by this
blocking behavior, a channel isn't receiving the logout event. We
currently don't have a good theory of why this is being caused. This in
turn is causing that the logout functionality is no longer working and
people no longer receive notifications, unless they refresh the page.
- This patchs makes this message non-blocking and thus making it
consistent with the other messages. We don't see a good reason why this
specific event needs to be blocking and the commit introducing it
doesn't offer a rationale either.
---
 modules/eventsource/manager.go   | 10 ----------
 modules/eventsource/messenger.go |  9 ---------
 routers/web/auth/auth.go         |  2 +-
 3 files changed, 1 insertion(+), 20 deletions(-)

diff --git a/modules/eventsource/manager.go b/modules/eventsource/manager.go
index 7ed2a82903..730cacd940 100644
--- a/modules/eventsource/manager.go
+++ b/modules/eventsource/manager.go
@@ -77,13 +77,3 @@ func (m *Manager) SendMessage(uid int64, message *Event) {
 		messenger.SendMessage(message)
 	}
 }
-
-// SendMessageBlocking sends a message to a particular user
-func (m *Manager) SendMessageBlocking(uid int64, message *Event) {
-	m.mutex.Lock()
-	messenger, ok := m.messengers[uid]
-	m.mutex.Unlock()
-	if ok {
-		messenger.SendMessageBlocking(message)
-	}
-}
diff --git a/modules/eventsource/messenger.go b/modules/eventsource/messenger.go
index 6df26716be..378e717126 100644
--- a/modules/eventsource/messenger.go
+++ b/modules/eventsource/messenger.go
@@ -66,12 +66,3 @@ func (m *Messenger) SendMessage(message *Event) {
 		}
 	}
 }
-
-// SendMessageBlocking sends the message to all registered channels and ensures it gets sent
-func (m *Messenger) SendMessageBlocking(message *Event) {
-	m.mutex.Lock()
-	defer m.mutex.Unlock()
-	for i := range m.channels {
-		m.channels[i] <- message
-	}
-}
diff --git a/routers/web/auth/auth.go b/routers/web/auth/auth.go
index 3181800211..3f1ed54bda 100644
--- a/routers/web/auth/auth.go
+++ b/routers/web/auth/auth.go
@@ -408,7 +408,7 @@ func HandleSignOut(ctx *context.Context) {
 // SignOut sign out from login status
 func SignOut(ctx *context.Context) {
 	if ctx.Doer != nil {
-		eventsource.GetManager().SendMessageBlocking(ctx.Doer.ID, &eventsource.Event{
+		eventsource.GetManager().SendMessage(ctx.Doer.ID, &eventsource.Event{
 			Name: "logout",
 			Data: ctx.Session.ID(),
 		})