Add experimental io_uring support

This just came off the presses, there are issues but this is for those who want to start playing with this with the risk that they could shoot themselves in the foot.

build.gradle

@@ -26,7 +26,7 @@ allprojects {
         junitVersion = '5.7.0'
         slf4jVersion = '1.7.30'
         log4jVersion = '2.13.3'
-        nettyVersion = '4.1.52.Final'
+        nettyVersion = '4.1.54.Final'
         guavaVersion = '25.1-jre'
         checkerFrameworkVersion = '3.6.1'
         configurateVersion = '3.7.1'

proxy/build.gradle

@@ -52,6 +52,7 @@ dependencies {
     implementation "io.netty:netty-transport-native-epoll:${nettyVersion}"
     implementation "io.netty:netty-transport-native-epoll:${nettyVersion}:linux-x86_64"
     implementation "io.netty:netty-transport-native-epoll:${nettyVersion}:linux-aarch64"
+    implementation "io.netty.incubator:netty-incubator-transport-native-io_uring:0.0.1.Final:linux-x86_64"
     implementation "io.netty:netty-resolver-dns:${nettyVersion}"
 
     implementation "org.apache.logging.log4j:log4j-api:${log4jVersion}"

proxy/src/main/java/com/velocitypowered/proxy/network/ConnectionManager.java

@@ -16,6 +16,7 @@ import io.netty.channel.ChannelOption;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.WriteBufferWaterMark;
 import io.netty.channel.epoll.EpollChannelOption;
+import io.netty.incubator.channel.uring.IOUringChannelOption;
 import io.netty.util.concurrent.GlobalEventExecutor;
 import java.net.InetSocketAddress;
 import java.util.HashMap;
@@ -23,6 +24,7 @@ import java.util.Map;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.asynchttpclient.AsyncHttpClient;
+import org.asynchttpclient.DefaultAsyncHttpClientConfig;
 import org.asynchttpclient.RequestBuilder;
 import org.asynchttpclient.filter.FilterContext;
 import org.asynchttpclient.filter.FilterContext.FilterContextBuilder;
@@ -64,20 +66,23 @@ public final class ConnectionManager {
     this.backendChannelInitializer = new BackendChannelInitializerHolder(
         new BackendChannelInitializer(this.server));
     this.resolver = new SeparatePoolInetNameResolver(GlobalEventExecutor.INSTANCE);
-    this.httpClient = asyncHttpClient(config()
+
-        .setEventLoopGroup(this.workerGroup)
+    DefaultAsyncHttpClientConfig.Builder httpClientBuilder = config()
         .setUserAgent(server.getVersion().getName() + "/" + server.getVersion().getVersion())
         .addRequestFilter(new RequestFilter() {
           @Override
           public <T> FilterContext<T> filter(FilterContext<T> ctx) {
             return new FilterContextBuilder<>(ctx)
-                .request(new RequestBuilder(ctx.getRequest())
+                .request(ctx.getRequest().toBuilder()
                     .setNameResolver(resolver)
                     .build())
                 .build();
           }
-        })
+        });
-        .build());
+    if (this.transportType != TransportType.IO_URING) {
+      httpClientBuilder = httpClientBuilder.setEventLoopGroup(this.workerGroup);
+    }
+    this.httpClient = asyncHttpClient(httpClientBuilder.build());
   }
 
   public void logChannelInformation() {
@@ -100,8 +105,12 @@ public final class ConnectionManager {
         .childOption(ChannelOption.IP_TOS, 0x18)
         .localAddress(address);
 
-    if (transportType == TransportType.EPOLL && server.getConfiguration().useTcpFastOpen()) {
+    if (server.getConfiguration().useTcpFastOpen()) {
-      bootstrap.option(EpollChannelOption.TCP_FASTOPEN, 3);
+      if (transportType == TransportType.EPOLL) {
+        bootstrap.option(EpollChannelOption.TCP_FASTOPEN, 3);
+      } else if (transportType == TransportType.IO_URING) {
+        bootstrap.option(IOUringChannelOption.TCP_FASTOPEN, 3);
+      }
     }
 
     bootstrap.bind()
@@ -156,8 +165,12 @@ public final class ConnectionManager {
             this.server.getConfiguration().getConnectTimeout())
         .group(group == null ? this.workerGroup : group)
         .resolver(this.resolver.asGroup());
-    if (transportType == TransportType.EPOLL && server.getConfiguration().useTcpFastOpen()) {
+    if (server.getConfiguration().useTcpFastOpen()) {
-      bootstrap.option(EpollChannelOption.TCP_FASTOPEN_CONNECT, true);
+      if (transportType == TransportType.EPOLL) {
+        bootstrap.option(EpollChannelOption.TCP_FASTOPEN_CONNECT, true);
+      } else if (transportType == TransportType.IO_URING) {
+        bootstrap.option(IOUringChannelOption.TCP_FASTOPEN_CONNECT, true);
+      }
     }
     return bootstrap;
   }

proxy/src/main/java/com/velocitypowered/proxy/network/TransportType.java

@@ -15,6 +15,11 @@ import io.netty.channel.socket.SocketChannel;
 import io.netty.channel.socket.nio.NioDatagramChannel;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
 import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.incubator.channel.uring.IOUring;
+import io.netty.incubator.channel.uring.IOUringDatagramChannel;
+import io.netty.incubator.channel.uring.IOUringEventLoopGroup;
+import io.netty.incubator.channel.uring.IOUringServerSocketChannel;
+import io.netty.incubator.channel.uring.IOUringSocketChannel;
 import java.util.concurrent.ThreadFactory;
 import java.util.function.BiFunction;
 
@@ -26,7 +31,11 @@ enum TransportType {
   EPOLL("epoll", EpollServerSocketChannel::new,
       EpollSocketChannel::new,
       EpollDatagramChannel::new,
-      (name, type) -> new EpollEventLoopGroup(0, createThreadFactory(name, type)));
+      (name, type) -> new EpollEventLoopGroup(0, createThreadFactory(name, type))),
+  IO_URING("io_uring", IOUringServerSocketChannel::new,
+      IOUringSocketChannel::new,
+      IOUringDatagramChannel::new,
+      (name, type) -> new IOUringEventLoopGroup(0, createThreadFactory(name, type)));
 
   final String name;
   final ChannelFactory<? extends ServerSocketChannel> serverSocketChannelFactory;
@@ -64,7 +73,9 @@ enum TransportType {
       return NIO;
     }
 
-    if (Epoll.isAvailable()) {
+    if (IOUring.isAvailable()) {
+      return IO_URING;
+    } else if (Epoll.isAvailable()) {
       return EPOLL;
     } else {
       return NIO;