PaperMC/Spigot-Server-Patches/0170-handle-PacketPlayInKeepAlive-async.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Thu, 5 Oct 2017 01:54:07 +0100
Subject: [PATCH] handle PacketPlayInKeepAlive async

In 1.12.2, Mojang moved the processing of PacketPlayInKeepAlive off the main
thread, while entirely correct for the server, this causes issues with
plugins which are expecting the PlayerQuitEvent on the main thread.

In order to counteract some bad behavior, we will post handling of the
disconnection to the main thread, but leave the actual processing of the packet
off the main thread.

also adding some additional logging in order to help work out what is causing
random disconnections for clients.

diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index 5429e91dec8aa29d8c641db09a1b4de0acd0f5bb..5b74b394bb832699d2d54030ee691fbe9648f170 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -2619,14 +2619,18 @@ public class PlayerConnection implements PacketListenerPlayIn {
 
     @Override
     public void a(PacketPlayInKeepAlive packetplayinkeepalive) {
-        PlayerConnectionUtils.ensureMainThread(packetplayinkeepalive, this, this.player.getWorldServer()); // CraftBukkit
+        //PlayerConnectionUtils.ensureMainThread(packetplayinkeepalive, this, this.player.getWorldServer()); // CraftBukkit // Paper - This shouldn't be on the main thread
         if (this.awaitingKeepAlive && packetplayinkeepalive.b() == this.h) {
             int i = (int) (SystemUtils.getMonotonicMillis() - this.lastKeepAlive);
 
             this.player.ping = (this.player.ping * 3 + i) / 4;
             this.awaitingKeepAlive = false;
         } else if (!this.isExemptPlayer()) {
+            // Paper start - This needs to be handled on the main thread for plugins
+            minecraftServer.scheduleOnMain(() -> {
             this.disconnect(new ChatMessage("disconnect.timeout"));
+            });
+            // Paper end
         }
 
     }