Paper/Spigot-Server-Patches/0346-Optimize-Network-Manager-and-add-advanced-packet-sup.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 6 May 2020 04:53:35 -0400
Subject: [PATCH] Optimize Network Manager and add advanced packet support

Adds ability for 1 packet to bundle other packets to follow it
Adds ability for a packet to delay sending more packets until a state is ready.

Removes synchronization from sending packets
Removes processing packet queue off of main thread
  - for the few cases where it is allowed, order is not necessary nor
    should it even be happening concurrently in first place (handshaking/login/status)

Ensures packets sent asynchronously are dispatched on main thread

This helps ensure safety for ProtocolLib as packet listeners
are commonly accessing world state. This will allow you to schedule
a packet to be sent async, but itll be dispatched sync for packet
listeners to process.

This should solve some deadlock risks

Also adds Netty Channel Flush Consolidation to reduce the amount of flushing

Also avoids spamming closed channel exception by rechecking closed state in dispatch
and then catch exceptions and close if they fire.

Part of this commit was authored by: Spottedleaf

diff --git a/src/main/java/net/minecraft/server/NetworkManager.java b/src/main/java/net/minecraft/server/NetworkManager.java
index b1dededc15cce686ead74a99bee64c89ac1de22c..289b17addd71aeab8a392e8f6a53d4c6329cf562 100644
--- a/src/main/java/net/minecraft/server/NetworkManager.java
+++ b/src/main/java/net/minecraft/server/NetworkManager.java
@@ -64,6 +64,10 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
     public int protocolVersion;
     public java.net.InetSocketAddress virtualHost;
     private static boolean enableExplicitFlush = Boolean.getBoolean("paper.explicit-flush");
+    // Optimize network
+    boolean isPending = true;
+    boolean queueImmunity = false;
+    EnumProtocol protocol;
     // Paper end
 
     public NetworkManager(EnumProtocolDirection enumprotocoldirection) {
@@ -87,6 +91,7 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
     }
 
     public void setProtocol(EnumProtocol enumprotocol) {
+        protocol = enumprotocol; // Paper
         this.channel.attr(NetworkManager.c).set(enumprotocol);
         this.channel.config().setAutoRead(true);
         NetworkManager.LOGGER.debug("Enabled auto read");
@@ -158,19 +163,82 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
         NetworkManager.LOGGER.debug("Set listener of {} to {}", this, packetlistener);
         this.packetListener = packetlistener;
     }
+    // Paper start
+    private EntityPlayer getPlayer() {
+        if (packetListener instanceof PlayerConnection) {
+            return ((PlayerConnection) packetListener).player;
+        } else {
+            return null;
+        }
+    }
+    private static class InnerUtil { // Attempt to hide these methods from ProtocolLib so it doesn't accidently pick them up.
+        private static java.util.List<Packet> buildExtraPackets(Packet packet) {
+            java.util.List<Packet> extra = packet.getExtraPackets();
+            if (extra == null || extra.isEmpty()) {
+                return null;
+            }
+            java.util.List<Packet> ret = new java.util.ArrayList<>(1 + extra.size());
+            buildExtraPackets0(extra, ret);
+            return ret;
+        }
+
+        private static void buildExtraPackets0(java.util.List<Packet> extraPackets, java.util.List<Packet> into) {
+            for (Packet extra : extraPackets) {
+                into.add(extra);
+                java.util.List<Packet> extraExtra = extra.getExtraPackets();
+                if (extraExtra != null && !extraExtra.isEmpty()) {
+                    buildExtraPackets0(extraExtra, into);
+                }
+            }
+        }
+        // Paper start
+        private static boolean canSendImmediate(NetworkManager networkManager, Packet<?> packet) {
+            return networkManager.isPending || networkManager.protocol != EnumProtocol.PLAY || networkManager.queueImmunity ||
+                packet instanceof PacketPlayOutKeepAlive ||
+                packet instanceof PacketPlayOutChat ||
+                packet instanceof PacketPlayOutTabComplete;
+        }
+        // Paper end
+    }
+    // Paper end
 
     public void sendPacket(Packet<?> packet) {
         this.sendPacket(packet, (GenericFutureListener) null);
     }
 
     public void sendPacket(Packet<?> packet, @Nullable GenericFutureListener<? extends Future<? super Void>> genericfuturelistener) {
-        if (this.isConnected()) {
-            this.o();
-            this.b(packet, genericfuturelistener);
-        } else {
-            this.packetQueue.add(new NetworkManager.QueuedPacket(packet, genericfuturelistener));
+        // Paper start - handle oversized packets better
+        boolean connected = this.isConnected();
+        if (!connected && !preparing) {
+            return; // Do nothing
+        }
+        packet.onPacketDispatch(getPlayer());
+        if (connected && (InnerUtil.canSendImmediate(this, packet) || (
+            MCUtil.isMainThread() && packet.isReady() && this.packetQueue.isEmpty() &&
+            (packet.getExtraPackets() == null || packet.getExtraPackets().isEmpty())
+        ))) {
+            this.dispatchPacket(packet, genericfuturelistener);
+            return;
         }
+        // write the packets to the queue, then flush - antixray hooks there already
+        java.util.List<Packet> extraPackets = InnerUtil.buildExtraPackets(packet);
+        boolean hasExtraPackets = extraPackets != null && !extraPackets.isEmpty();
+        if (!hasExtraPackets) {
+            this.packetQueue.add(new NetworkManager.QueuedPacket(packet, genericfuturelistener));
+        } else {
+            java.util.List<NetworkManager.QueuedPacket> packets = new java.util.ArrayList<>(1 + extraPackets.size());
+            packets.add(new NetworkManager.QueuedPacket(packet, null)); // delay the future listener until the end of the extra packets
+
+            for (int i = 0, len = extraPackets.size(); i < len;) {
+                Packet extra = extraPackets.get(i);
+                boolean end = ++i == len;
+                packets.add(new NetworkManager.QueuedPacket(extra, end ? genericfuturelistener : null)); // append listener to the end
+            }
 
+            this.packetQueue.addAll(packets); // atomic
+        }
+        this.sendPacketQueue();
+        // Paper end
     }
 
     private void dispatchPacket(Packet<?> packet, @Nullable GenericFutureListener<? extends Future<? super Void>> genericFutureListener) { this.b(packet, genericFutureListener); } // Paper - OBFHELPER
@@ -184,51 +252,116 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
             this.channel.config().setAutoRead(false);
         }
 
+        EntityPlayer player = getPlayer(); // Paper
         if (this.channel.eventLoop().inEventLoop()) {
             if (enumprotocol != enumprotocol1) {
                 this.setProtocol(enumprotocol);
             }
+            // Paper start
+            if (!isConnected()) {
+                packet.onPacketDispatchFinish(player, null);
+                return;
+            }
+            try {
+                // Paper end
 
             ChannelFuture channelfuture = this.channel.writeAndFlush(packet);
 
             if (genericfuturelistener != null) {
                 channelfuture.addListener(genericfuturelistener);
             }
+            // Paper start
+            if (packet.hasFinishListener()) {
+                channelfuture.addListener((ChannelFutureListener) channelFuture -> packet.onPacketDispatchFinish(player, channelFuture));
+            }
+            // Paper end
 
             channelfuture.addListener(ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE);
+            // Paper start
+            } catch (Exception e) {
+                LOGGER.error("NetworkException: " + player, e);
+                close(new ChatMessage("disconnect.genericReason", "Internal Exception: " + e.getMessage()));;
+                packet.onPacketDispatchFinish(player, null);
+            }
+            // Paper end
         } else {
             this.channel.eventLoop().execute(() -> {
                 if (enumprotocol != enumprotocol1) {
                     this.setProtocol(enumprotocol);
                 }
 
+                // Paper start
+                if (!isConnected()) {
+                    packet.onPacketDispatchFinish(player, null);
+                    return;
+                }
+                try {
+                    // Paper end
                 ChannelFuture channelfuture1 = this.channel.writeAndFlush(packet);
 
+
                 if (genericfuturelistener != null) {
                     channelfuture1.addListener(genericfuturelistener);
                 }
+                // Paper start
+                if (packet.hasFinishListener()) {
+                    channelfuture1.addListener((ChannelFutureListener) channelFuture -> packet.onPacketDispatchFinish(player, channelFuture));
+                }
+                // Paper end
 
                 channelfuture1.addListener(ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE);
+                // Paper start
+                } catch (Exception e) {
+                    LOGGER.error("NetworkException: " + player, e);
+                    close(new ChatMessage("disconnect.genericReason", "Internal Exception: " + e.getMessage()));;
+                    packet.onPacketDispatchFinish(player, null);
+                }
+                // Paper end
             });
         }
 
     }
 
-    private void sendPacketQueue() { this.o(); } // Paper - OBFHELPER
-    private void o() {
-        if (this.channel != null && this.channel.isOpen()) {
-            Queue queue = this.packetQueue;
-
+    // Paper start - rewrite this to be safer on
+    private boolean sendPacketQueue() { return this.o(); } // OBFHELPER // void -> boolean
+    private boolean o() { // void -> boolean
+        if (!isConnected()) {
+            return true;
+        }
+        if (MCUtil.isMainThread()) {
+            return processQueue();
+        } else if (isPending) {
+            // Should only happen during login/status stages
             synchronized (this.packetQueue) {
-                NetworkManager.QueuedPacket networkmanager_queuedpacket;
-
-                while ((networkmanager_queuedpacket = (NetworkManager.QueuedPacket) this.packetQueue.poll()) != null) {
-                    this.b(networkmanager_queuedpacket.a, networkmanager_queuedpacket.b);
-                }
+                return this.processQueue();
+            }
+        }
+        return false;
+    }
+    private boolean processQueue() {
+        if (this.packetQueue.isEmpty()) return true;
+        // If we are on main, we are safe here in that nothing else should be processing queue off main anymore
+        // But if we are not on main due to login/status, the parent is synchronized on packetQueue
+        java.util.Iterator<QueuedPacket> iterator = this.packetQueue.iterator();
+        while (iterator.hasNext()) {
+            NetworkManager.QueuedPacket queued = iterator.next(); // poll -> peek
+
+            // Fix NPE (Spigot bug caused by handleDisconnection())
+            if (queued == null) {
+                return true;
+            }
 
+            Packet<?> packet = queued.getPacket();
+            if (!packet.isReady()) {
+                return false;
+            } else {
+                iterator.remove();
+                this.dispatchPacket(packet, queued.getGenericFutureListener());
             }
         }
+        return true;
     }
+    // Paper end
 
     public void a() {
         this.o();
@@ -257,9 +390,21 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
         return this.socketAddress;
     }
 
+    // Paper start
+    public void clearPacketQueue() {
+        EntityPlayer player = getPlayer();
+        packetQueue.forEach(queuedPacket -> {
+            Packet<?> packet = queuedPacket.getPacket();
+            if (packet.hasFinishListener()) {
+                packet.onPacketDispatchFinish(player, null);
+            }
+        });
+        packetQueue.clear();
+    } // Paper end
     public void close(IChatBaseComponent ichatbasecomponent) {
         // Spigot Start
         this.preparing = false;
+        clearPacketQueue(); // Paper
         // Spigot End
         if (this.channel.isOpen()) {
             this.channel.close(); // We can't wait as this may be called from an event loop.
@@ -335,7 +480,7 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
                 } else if (this.i() != null) {
                     this.i().a(new ChatMessage("multiplayer.disconnect.generic", new Object[0]));
                 }
-                this.packetQueue.clear(); // Free up packet queue.
+                clearPacketQueue(); // Paper
                 // Paper start - Add PlayerConnectionCloseEvent
                 final PacketListener packetListener = this.i();
                 if (packetListener instanceof PlayerConnection) {
diff --git a/src/main/java/net/minecraft/server/Packet.java b/src/main/java/net/minecraft/server/Packet.java
index 2d8e6a2f4a0c3c5d74a647d7164b0028781d3bf5..c5edf8c4b01cc7ddac06797133e6fd13ec5b6592 100644
--- a/src/main/java/net/minecraft/server/Packet.java
+++ b/src/main/java/net/minecraft/server/Packet.java
@@ -11,6 +11,20 @@ public interface Packet<T extends PacketListener> {
     void a(T t0);
 
     // Paper start
+
+    /**
+     * @param player Null if not at PLAY stage yet
+     */
+    default void onPacketDispatch(@javax.annotation.Nullable EntityPlayer player) {}
+
+    /**
+     * @param player Null if not at PLAY stage yet
+     * @param future Can be null if packet was cancelled
+     */
+    default void onPacketDispatchFinish(@javax.annotation.Nullable EntityPlayer player, @javax.annotation.Nullable io.netty.channel.ChannelFuture future) {}
+    default boolean hasFinishListener() { return false; }
+    default boolean isReady() { return true; }
+    default java.util.List<Packet> getExtraPackets() { return null; }
     default boolean packetTooLarge(NetworkManager manager) {
         return false;
     }
diff --git a/src/main/java/net/minecraft/server/PlayerList.java b/src/main/java/net/minecraft/server/PlayerList.java
index 707b4523536dd6c3192451982e6e33ea4e263053..dc86dae6ff15d38fcc3af2a5f65119aa2daf08f0 100644
--- a/src/main/java/net/minecraft/server/PlayerList.java
+++ b/src/main/java/net/minecraft/server/PlayerList.java
@@ -143,6 +143,7 @@ public abstract class PlayerList {
 
         // CraftBukkit - getType()
         // Spigot - view distance
+        networkmanager.queueImmunity = true; // Paper
         playerconnection.sendPacket(new PacketPlayOutLogin(entityplayer.getId(), entityplayer.playerInteractManager.getGameMode(), WorldData.c(worlddata.getSeed()), worlddata.isHardcore(), worldserver.worldProvider.getDimensionManager().getType(), this.getMaxPlayers(), worlddata.getType(), worldserver.spigotConfig.viewDistance, flag1, !flag));
         entityplayer.getBukkitEntity().sendSupportedChannels(); // CraftBukkit
         playerconnection.sendPacket(new PacketPlayOutCustomPayload(PacketPlayOutCustomPayload.a, (new PacketDataSerializer(Unpooled.buffer())).a(this.getServer().getServerModName())));
@@ -152,6 +153,7 @@ public abstract class PlayerList {
         playerconnection.sendPacket(new PacketPlayOutRecipeUpdate(this.server.getCraftingManager().b()));
         playerconnection.sendPacket(new PacketPlayOutTags(this.server.getTagRegistry()));
         playerconnection.sendPacket(new PacketPlayOutEntityStatus(entityplayer, (byte) (worldserver.getGameRules().getBoolean(GameRules.REDUCED_DEBUG_INFO) ? 22 : 23))); // Paper - fix this rule not being initialized on the client
+        networkmanager.queueImmunity = false; // Paper
         this.d(entityplayer);
         entityplayer.getStatisticManager().c();
         entityplayer.B().a(entityplayer);
diff --git a/src/main/java/net/minecraft/server/ServerConnection.java b/src/main/java/net/minecraft/server/ServerConnection.java
index 37a22ba6f7a2ac54759428d23d5ea9787bb557f7..ceecb78ff879e4d6a3295b05d04deb01b7fb1da6 100644
--- a/src/main/java/net/minecraft/server/ServerConnection.java
+++ b/src/main/java/net/minecraft/server/ServerConnection.java
@@ -41,10 +41,12 @@ public class ServerConnection {
     private final List<NetworkManager> connectedChannels = Collections.synchronizedList(Lists.newArrayList());
     // Paper start - prevent blocking on adding a new network manager while the server is ticking
     private final java.util.Queue<NetworkManager> pending = new java.util.concurrent.ConcurrentLinkedQueue<>();
+    private static final boolean disableFlushConsolidation = Boolean.getBoolean("Paper.disableFlushConsolidate"); // Paper
     private void addPending() {
         NetworkManager manager = null;
         while ((manager = pending.poll()) != null) {
             connectedChannels.add(manager);
+            manager.isPending = false;
         }
     }
     // Paper end
@@ -79,6 +81,7 @@ public class ServerConnection {
                         ;
                     }
 
+                    if (!disableFlushConsolidation) channel.pipeline().addFirst(new io.netty.handler.flush.FlushConsolidationHandler()); // Paper
                     channel.pipeline().addLast("timeout", new ReadTimeoutHandler(30)).addLast("legacy_query", new LegacyPingHandler(ServerConnection.this)).addLast("splitter", new PacketSplitter()).addLast("decoder", new PacketDecoder(EnumProtocolDirection.SERVERBOUND)).addLast("prepender", new PacketPrepender()).addLast("encoder", new PacketEncoder(EnumProtocolDirection.CLIENTBOUND));
                     NetworkManager networkmanager = new NetworkManager(EnumProtocolDirection.SERVERBOUND);