Leaf/leaf-server/minecraft-patches/features/0125-Rewrite-queue-on-Connection.flushQueue.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Taiyou06 <kaandindar21@gmail.com>
Date: Fri, 21 Feb 2025 15:52:42 +0100
Subject: [PATCH] Rewrite queue on Connection.flushQueue


diff --git a/net/minecraft/network/Connection.java b/net/minecraft/network/Connection.java
index 00a82873d226f113278632a53c0faca420dd67d4..9aeadf792eb7c6c39044df00fa7ff80017ba72d0 100644
--- a/net/minecraft/network/Connection.java
+++ b/net/minecraft/network/Connection.java
@@ -85,7 +85,7 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
     private static final ProtocolInfo<ServerHandshakePacketListener> INITIAL_PROTOCOL = HandshakeProtocols.SERVERBOUND;
     private final PacketFlow receiving;
     private volatile boolean sendLoginDisconnect = true;
-    private final Queue<WrappedConsumer> pendingActions = Queues.newConcurrentLinkedQueue(); // Paper - Optimize network
+    private final Queue<WrappedConsumer> pendingActions = org.dreeam.leaf.config.modules.network.ConnectionFlushQueueRewrite.enabled ? new java.util.ArrayDeque<>() : Queues.newConcurrentLinkedQueue(); // Paper - Optimize network // Leaf - Rewrite queue on Connection.flushQueue
     public Channel channel;
     public SocketAddress address;
     // Spigot start
@@ -541,9 +541,17 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
         if (io.papermc.paper.util.MCUtil.isMainThread()) {
             return this.processQueue();
         } else if (this.isPending) {
-            // Should only happen during login/status stages
-            synchronized (this.pendingActions) {
-                return this.processQueue();
+            // Leaf start - Rewrite queue on Connection.flushQueue
+            if (org.dreeam.leaf.config.modules.network.ConnectionFlushQueueRewrite.enabled) {
+                // Submit to the event loop to ensure thread confinement
+                this.channel.eventLoop().execute(this::processQueue);
+                return false;
+            } else {
+                // Original Paper behavior
+                synchronized (this.pendingActions) {
+                    return this.processQueue();
+                    // Leaf end - Rewrite queue on Connection.flushQueue
+                }
             }
         }
         return false;
@@ -554,6 +562,24 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
             return true;
         }
 
+        // Leaf start - Rewrite queue on Connection.flushQueue
+        if (org.dreeam.leaf.config.modules.network.ConnectionFlushQueueRewrite.enabled) {
+            WrappedConsumer queued;
+            while ((queued = this.pendingActions.poll()) != null) {
+                if (queued instanceof PacketSendAction packetSendAction) {
+                    final Packet<?> packet = packetSendAction.packet;
+                    if (!packet.isReady()) {
+                        // Re-add to the front and exit
+                        this.pendingActions.add(queued);
+                        return false;
+                    }
+                }
+
+                if (queued.tryMarkConsumed()) {
+                    queued.accept(this);
+                }
+            }
+        } else {
         // 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
         final java.util.Iterator<WrappedConsumer> iterator = this.pendingActions.iterator();
@@ -581,6 +607,8 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
                 queued.accept(this);
             }
         }
+        }
+        // Leaf end - Rewrite queue on Connection.flushQueue
         return true;
     }
     // Paper end - Optimize network
@@ -913,6 +941,31 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
     // Paper start - Optimize network
     public void clearPacketQueue() {
         final net.minecraft.server.level.ServerPlayer player = getPlayer();
+
+        // Leaf start - Rewrite queue on Connection.flushQueue
+        if (org.dreeam.leaf.config.modules.network.ConnectionFlushQueueRewrite.enabled) {
+            // When using Leaf's queue rewrite, ensure thread safety via event loop
+            if (this.channel != null && !this.channel.eventLoop().inEventLoop()) {
+                this.channel.eventLoop().execute(() -> this.clearPacketQueue());
+                return;
+            }
+
+            // Take a snapshot to avoid ConcurrentModificationException
+            java.util.List<Consumer<Connection>> queueSnapshot = new java.util.ArrayList<>(this.pendingActions);
+
+            for (Consumer<Connection> queuedAction : queueSnapshot) {
+                if (queuedAction instanceof PacketSendAction packetSendAction) {
+                    final Packet<?> packet = packetSendAction.packet;
+                    if (packet.hasFinishListener()) {
+                        packet.onPacketDispatchFinish(player, null);
+                    }
+                }
+            }
+
+            this.pendingActions.clear();
+        } else {
+        // Original Paper behavior - use synchronization
+        synchronized (this.pendingActions) {
         for (final Consumer<Connection> queuedAction : this.pendingActions) {
             if (queuedAction instanceof PacketSendAction packetSendAction) {
                 final Packet<?> packet = packetSendAction.packet;
@@ -922,6 +975,9 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
             }
         }
         this.pendingActions.clear();
+            }
+        }
+        // Leaf end - Rewrite queue on Connection.flushQueue
     }
 
     private static class InnerUtil { // Attempt to hide these methods from ProtocolLib, so it doesn't accidently pick them up.