Paper/patches/server/0156-handle-ServerboundKeepAlivePacket-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 ServerboundKeepAlivePacket async

In 1.12.2, Mojang moved the processing of ServerboundKeepAlivePacket 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/network/ServerCommonPacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
index 70168fb930c24689c98da064f7d04cc98d729358..75a61cab28928a145fd22159822dd04844c626ac 100644
--- a/src/main/java/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
@@ -83,14 +83,18 @@ public abstract class ServerCommonPacketListenerImpl implements ServerCommonPack
 
     @Override
     public void handleKeepAlive(ServerboundKeepAlivePacket packet) {
-        PacketUtils.ensureRunningOnSameThread(packet, this, this.player.serverLevel()); // CraftBukkit
+        //PacketUtils.ensureRunningOnSameThread(packet, this, this.player.serverLevel()); // CraftBukkit // Paper - This shouldn't be on the main thread
         if (this.keepAlivePending && packet.getId() == this.keepAliveChallenge) {
             int i = (int) (Util.getMillis() - this.keepAliveTime);
 
             this.latency = (this.latency * 3 + i) / 4;
             this.keepAlivePending = false;
         } else if (!this.isSingleplayerOwner()) {
-            this.disconnect(ServerCommonPacketListenerImpl.TIMEOUT_DISCONNECTION_MESSAGE);
+            // Paper start - This needs to be handled on the main thread for plugins
+            server.submit(() -> {
+                this.disconnect(ServerCommonPacketListenerImpl.TIMEOUT_DISCONNECTION_MESSAGE);
+            });
+            // Paper endg
         }
 
     }