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 73d40f768b6882062656cba30acc5f86f26d1a96..07d2e60bcd7d1f3ba2f8005ec496561b3648ae86 100644
--- a/src/main/java/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
@@ -117,14 +117,18 @@ 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 - handle ServerboundKeepAlivePacket async
         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 end - This needs to be handled on the main thread for plugins
         }
 
     }