From eeb374798b10786bb87175796b55bed0275d56c7 Mon Sep 17 00:00:00 2001
From: polo1k <briankennydev@gmail.com>
Date: Fri, 24 Jan 2020 13:13:01 +1100
Subject: [PATCH] #2710: Store queue of pending keepalives

This allows the server to send them at a rate greater than the client reply time.
---
 .../java/net/md_5/bungee/ServerConnection.java     | 14 ++++++++++++--
 .../main/java/net/md_5/bungee/UserConnection.java  |  3 ---
 .../md_5/bungee/connection/DownstreamBridge.java   |  7 +++++--
 .../net/md_5/bungee/connection/UpstreamBridge.java |  7 +++++--
 4 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/proxy/src/main/java/net/md_5/bungee/ServerConnection.java b/proxy/src/main/java/net/md_5/bungee/ServerConnection.java
index 06a0afd5..86461043 100644
--- a/proxy/src/main/java/net/md_5/bungee/ServerConnection.java
+++ b/proxy/src/main/java/net/md_5/bungee/ServerConnection.java
@@ -3,6 +3,9 @@ package net.md_5.bungee;
 import com.google.common.base.Preconditions;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
+import java.util.LinkedList;
+import java.util.Queue;
+import lombok.Data;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import lombok.Setter;
@@ -26,8 +29,7 @@ public class ServerConnection implements Server
     @Getter
     private final boolean forgeServer = false;
     @Getter
-    @Setter
-    private long sentPingId = -1;
+    private final Queue<KeepAliveData> keepAlives = new LinkedList<>();
 
     private final Unsafe unsafe = new Unsafe()
     {
@@ -87,4 +89,12 @@ public class ServerConnection implements Server
     {
         return unsafe;
     }
+
+    @Data
+    public static class KeepAliveData
+    {
+
+        private final long id;
+        private final long time;
+    }
 }
diff --git a/proxy/src/main/java/net/md_5/bungee/UserConnection.java b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
index 3d7e9043..afcae3a2 100644
--- a/proxy/src/main/java/net/md_5/bungee/UserConnection.java
+++ b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
@@ -93,9 +93,6 @@ public final class UserConnection implements ProxiedPlayer
     /*========================================================================*/
     @Getter
     @Setter
-    private long sentPingTime;
-    @Getter
-    @Setter
     private int ping = 100;
     @Getter
     @Setter
diff --git a/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java b/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java
index b66712d2..e53a3ff9 100644
--- a/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java
+++ b/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java
@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Map;
 import lombok.RequiredArgsConstructor;
 import net.md_5.bungee.ServerConnection;
+import net.md_5.bungee.ServerConnection.KeepAliveData;
 import net.md_5.bungee.UserConnection;
 import net.md_5.bungee.Util;
 import net.md_5.bungee.api.ProxyServer;
@@ -124,8 +125,10 @@ public class DownstreamBridge extends PacketHandler
     @Override
     public void handle(KeepAlive alive) throws Exception
     {
-        server.setSentPingId( alive.getRandomId() );
-        con.setSentPingTime( System.currentTimeMillis() );
+        if ( server.getKeepAlives().size() < bungee.getConfig().getTimeout() / 50 ) // Allow a theoretical maximum of 1 keepalive per tick
+        {
+            server.getKeepAlives().add( new KeepAliveData( alive.getRandomId(), System.currentTimeMillis() ) );
+        }
     }
 
     @Override
diff --git a/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java b/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
index 540cf213..6b888c85 100644
--- a/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
+++ b/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
@@ -9,6 +9,7 @@ import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 import net.md_5.bungee.BungeeCord;
+import net.md_5.bungee.ServerConnection.KeepAliveData;
 import net.md_5.bungee.UserConnection;
 import net.md_5.bungee.Util;
 import net.md_5.bungee.api.ProxyServer;
@@ -121,9 +122,11 @@ public class UpstreamBridge extends PacketHandler
     @Override
     public void handle(KeepAlive alive) throws Exception
     {
-        if ( alive.getRandomId() == con.getServer().getSentPingId() )
+        KeepAliveData keepAliveData = con.getServer().getKeepAlives().poll();
+
+        if ( keepAliveData != null && alive.getRandomId() == keepAliveData.getId() )
         {
-            int newPing = (int) ( System.currentTimeMillis() - con.getSentPingTime() );
+            int newPing = (int) ( System.currentTimeMillis() - keepAliveData.getTime() );
             con.getTabListHandler().onPingChange( newPing );
             con.setPing( newPing );
         } else