Resolve "not in event loop" issue on Geyser-Velocity with use-direct-connection enabled (#5720)

bootstrap/velocity/build.gradle.kts

@@ -8,6 +8,10 @@ dependencies {
     annotationProcessor(libs.velocity.api)
     api(projects.core)
 
+    compileOnly(libs.velocity.proxy)
+    compileOnly(libs.netty.transport.native.io.uring)
+    compileOnly(libs.netty.transport.native.kqueue)
+
     compileOnlyApi(libs.velocity.api)
     api(libs.cloud.velocity)
 }

bootstrap/velocity/src/main/java/org/geysermc/geyser/platform/velocity/GeyserVelocityInjector.java

@@ -26,6 +26,7 @@
 package org.geysermc.geyser.platform.velocity;
 
 import com.velocitypowered.api.proxy.ProxyServer;
+import com.velocitypowered.proxy.network.TransportType;
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
@@ -33,18 +34,25 @@ import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.IoEventLoop;
+import io.netty.channel.IoEventLoopGroup;
+import io.netty.channel.IoHandler;
 import io.netty.channel.IoHandlerFactory;
 import io.netty.channel.MultiThreadIoEventLoopGroup;
+import io.netty.channel.SingleThreadIoEventLoop;
 import io.netty.channel.WriteBufferWaterMark;
+import io.netty.channel.epoll.EpollIoHandler;
+import io.netty.channel.kqueue.KQueueIoHandler;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalIoHandler;
+import io.netty.channel.nio.NioIoHandler;
+import io.netty.channel.uring.IoUringIoHandler;
 import io.netty.util.concurrent.DefaultThreadFactory;
+import io.netty.util.concurrent.ThreadAwareExecutor;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.geysermc.geyser.GeyserBootstrap;
-import org.geysermc.geyser.GeyserImpl;
 import org.geysermc.geyser.network.netty.GeyserInjector;
+import org.geysermc.geyser.network.netty.IoHandlerWrapper;
 import org.geysermc.geyser.network.netty.LocalServerChannelWrapper;
-import org.geysermc.geyser.network.netty.WatchedSingleThreadIoEventLoop;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
@@ -86,9 +94,18 @@ public class GeyserVelocityInjector extends GeyserInjector {
 
         Field workerGroupField = connectionManagerClass.getDeclaredField("workerGroup");
         workerGroupField.setAccessible(true);
-        EventLoopGroup workerGroup = (EventLoopGroup) workerGroupField.get(connectionManager);
+        IoEventLoopGroup workerGroup = (IoEventLoopGroup) workerGroupField.get(connectionManager);
 
-        EventLoopGroup wrapperGroup = new MultiThreadIoEventLoopGroup(LocalIoHandler.newFactory()) {
+        var factory = LocalIoHandler.newFactory();
+        var nativeFactory = getNativeHandlerFactory();
+        var wrapperFactory = new IoHandlerFactory() {
+            @Override
+            public IoHandler newHandler(ThreadAwareExecutor ioExecutor) {
+                return new IoHandlerWrapper(factory.newHandler(ioExecutor), nativeFactory.newHandler(ioExecutor));
+            }
+        };
+
+        EventLoopGroup wrapperGroup = new MultiThreadIoEventLoopGroup(factory) {
             @Override
             protected ThreadFactory newDefaultThreadFactory() {
                 return new DefaultThreadFactory("Geyser Backend Worker Group", Thread.MAX_PRIORITY);
@@ -96,7 +113,7 @@ public class GeyserVelocityInjector extends GeyserInjector {
 
             @Override
             protected IoEventLoop newChild(Executor executor, IoHandlerFactory ioHandlerFactory, Object... args) {
-                return new WatchedSingleThreadIoEventLoop(workerGroup, this, executor, ioHandlerFactory);
+                return new SingleThreadIoEventLoop(workerGroup, executor, wrapperFactory);
             }
         };
 
@@ -126,4 +143,13 @@ public class GeyserVelocityInjector extends GeyserInjector {
         this.localChannel = channelFuture;
         this.serverSocketAddress = channelFuture.channel().localAddress();
     }
+
+    private static IoHandlerFactory getNativeHandlerFactory() {
+        return switch (TransportType.bestType()) {
+            case NIO -> NioIoHandler.newFactory();
+            case EPOLL -> EpollIoHandler.newFactory();
+            case KQUEUE -> KQueueIoHandler.newFactory();
+            case IO_URING -> IoUringIoHandler.newFactory();
+        };
+    }
 }

core/src/main/java/org/geysermc/geyser/network/netty/WatchedSingleThreadIoEventLoop.java

@@ -1,61 +0,0 @@
-/*
- * Copyright (c) 2025 GeyserMC. http://geysermc.org
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- *
- * @author GeyserMC
- * @link https://github.com/GeyserMC/Geyser
- */
-
-package org.geysermc.geyser.network.netty;
-
-import io.netty.channel.Channel;
-import io.netty.channel.ChannelFuture;
-import io.netty.channel.EventLoopGroup;
-import io.netty.channel.IoEventLoopGroup;
-import io.netty.channel.IoHandlerFactory;
-import io.netty.channel.SingleThreadIoEventLoop;
-
-import java.util.concurrent.Executor;
-
-public class WatchedSingleThreadIoEventLoop extends SingleThreadIoEventLoop {
-    private final EventLoopGroup trueWorkerGroup;
-
-    public WatchedSingleThreadIoEventLoop(EventLoopGroup trueWorkerGroup, IoEventLoopGroup parent,
-                                          Executor executor, IoHandlerFactory ioHandlerFactory) {
-        super(parent, executor, ioHandlerFactory);
-        this.trueWorkerGroup = trueWorkerGroup;
-    }
-
-    @Override
-    @SuppressWarnings("deprecation")
-    public ChannelFuture register(Channel channel) {
-        if (channel.getClass().getName().startsWith("org.geysermc.geyser")) {
-            return super.register(channel);
-        }
-        // Starting with Netty 4.2, channels/event loops are very picky with what can be accepted for each.
-        // For example, IoUringIoHandler (on a Linux machine, what Velocity's worker group will be)
-        // will not accept LocalChannels on bootstrap creation in GeyserVelocityInjector.
-        // And using a MultiThreadEventLoopGroup with LocalIoHandler will throw an error when trying to
-        // connect to the backend server.
-        // Inserting ourselves here allows our local channels to use the event loop made for LocalChannels,
-        // while re-using the settings and style of Velocity.
-        return this.trueWorkerGroup.register(channel);
-    }
-}

gradle/libs.versions.toml

@@ -130,6 +130,7 @@ minecraftauth = { group = "net.raphimc", name = "MinecraftAuth", version.ref = "
 mcprotocollib = { group = "org.geysermc.mcprotocollib", name = "protocol", version.ref = "mcprotocollib" }
 raknet = { group = "org.cloudburstmc.netty", name = "netty-transport-raknet", version.ref = "raknet" }
 terminalconsoleappender = { group = "net.minecrell", name = "terminalconsoleappender", version.ref = "terminalconsoleappender" }
+velocity-proxy = { group = "com.velocitypowered", name = "velocity-proxy", version.ref = "velocity" }
 velocity-api = { group = "com.velocitypowered", name = "velocity-api", version.ref = "velocity" }
 viaproxy = { group = "net.raphimc", name = "ViaProxy", version.ref = "viaproxy" }
 viaversion = { group = "com.viaversion", name = "viaversion", version.ref = "viaversion" }