Improve documentation

vertx-core/pom.xml

@@ -371,6 +371,21 @@
               </classpathDependencyExcludes>
             </configuration>
           </execution>
+          <execution>
+            <id>io_uring</id>
+            <goals>
+              <goal>integration-test</goal>
+              <goal>verify</goal>
+            </goals>
+            <configuration>
+              <includes>
+                <include>io/vertx/it/transport/IoUringTest.java</include>
+              </includes>
+              <classpathDependencyExcludes>
+                <classpathDependencyExclude>io.netty:netty-transport-classes-epoll</classpathDependencyExclude>
+              </classpathDependencyExcludes>
+            </configuration>
+          </execution>
           <execution>
             <id>connect-to-tls-trusted-server</id>
             <goals>

vertx-core/src/main/asciidoc/index.adoc

@@ -1022,8 +1022,7 @@ Vert.x can run with http://netty.io/wiki/native-transports.html[native transport
 {@link examples.CoreExamples#configureNative()}
 ----
 
-NOTE: preferring native transport will not prevent the application to execute (for example if a JAR is missing).
-If your application requires native transport, you need to check {@link io.vertx.core.Vertx#isNativeTransportEnabled()}.
+NOTE: preferring native transport will not prevent the application to execute (for example a native dependency might be missing). If your application requires native transport, you need to check {@link io.vertx.core.Vertx#isNativeTransportEnabled()}.
 
 You can also explicitly configure the transport to use:
 
@@ -1034,13 +1033,21 @@ You can also explicitly configure the transport to use:
 
 === Native epoll
 
+Native on Linux gives you extra networking options:
+
+* `SO_REUSEPORT`
+* `TCP_QUICKACK`
+* `TCP_CORK`
+* `TCP_FASTOPEN`
+* `TCP_USER_TIMEOUT`
+
 You need to add the following dependency in your classpath:
 
 [source,xml]
 ----
 <dependency>
   <groupId>io.netty</groupId>
-  <artifactId>netty-transport-native-io_uring</artifactId>
+  <artifactId>netty-transport-native-epoll</artifactId>
   <classifier>linux-x86_64</classifier>
   <!--<version>Should align with netty version that Vert.x uses</version>-->
 </dependency>
@@ -1054,8 +1061,8 @@ You need to add the following dependency in your classpath:
 ----
 <dependency>
   <groupId>io.netty</groupId>
-  <artifactId>netty-transport-native-epoll</artifactId>
   <classifier>linux-x86_64</classifier>
+  <artifactId>netty-transport-native-io_uring</artifactId>
   <!--<version>Should align with netty version that Vert.x uses</version>-->
 </dependency>
 ----

vertx-core/src/main/java/io/vertx/core/impl/Utils.java

@@ -25,26 +25,35 @@ public class Utils {
 
   private static final boolean isLinux;
   private static final boolean isWindows;
+  private static final boolean isOsx;
 
   static {
     isLinux = "linux".equals(PlatformDependent.normalizedOs());
     isWindows = PlatformDependent.isWindows();
+    isOsx = PlatformDependent.isOsx();
   }
 
   /**
-   * @return true, if running on Linux
+   * @return {@code true}, if running on Linux
    */
   public static boolean isLinux() {
     return isLinux;
   }
 
   /**
-   * @return true, if running on Windows
+   * @return {@code true}, if running on Windows
    */
   public static boolean isWindows() {
     return isWindows;
   }
 
+  /**
+   * @return {@code true}, if running on Mac
+   */
+  public static boolean isOsx() {
+    return isOsx;
+  }
+
   @SuppressWarnings("unchecked")
   public static <E extends Throwable> void throwAsUnchecked(Throwable t) throws E {
     throw (E) t;

vertx-core/src/main/java/io/vertx/core/transport/Transport.java

@@ -10,6 +10,7 @@
  */
 package io.vertx.core.transport;
 
+import io.vertx.core.impl.Utils;
 import io.vertx.core.impl.transports.NioTransport;
 import io.vertx.core.impl.transports.TransportInternal;
 import io.vertx.core.impl.transports.TransportLoader;
@@ -50,15 +51,30 @@ public interface Transport {
    * Return a native transport suitable for the OS
    *
    * <ul>
-   *   <li>{@link #EPOLL} on Linux</li>
+   *   <li>{@link #EPOLL} or {@link #IO_URING} on Linux</li>
    *   <li>{@link #KQUEUE} on Mac</li>
    * </ul>
    *
    * @return a native transport, it might return an unavailable transport ({@link Transport#available()}) then {@link Transport#unavailabilityCause()}
-   * can be used to check the error preventing its usafe, {@code null} can be returned when no native transport can be loaded.
+   * can be used to check the error preventing its unsafe, {@code null} can be returned when no native transport can be loaded.
    */
   static Transport nativeTransport() {
-    return KQUEUE != null ? KQUEUE : EPOLL;
+    Transport transport;
+    if (Utils.isLinux()) {
+      transport = EPOLL;
+      if (transport != null) {
+        if (!transport.available() && IO_URING != null && IO_URING.available()) {
+          transport = IO_URING;
+        }
+      } else {
+        transport = IO_URING;
+      }
+    } else if (Utils.isOsx()) {
+      transport = KQUEUE;
+    } else {
+      transport = null;
+    }
+    return transport;
   }
 
   /**

vertx-core/src/test/java/io/vertx/it/transport/IoUringTest.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2011-2024 Contributors to the Eclipse Foundation
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ * which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ */
+package io.vertx.it.transport;
+
+import io.vertx.core.impl.Utils;
+import io.vertx.core.transport.Transport;
+import io.vertx.test.core.AsyncTestBase;
+import org.junit.Test;
+
+public class IoUringTest extends AsyncTestBase {
+  @Test
+  public void testNativeTransportFallback() {
+    if (Utils.isLinux()) {
+      Transport nativeTransport = Transport.nativeTransport();
+      assertEquals("io_uring", nativeTransport.name());
+    }
+  }
+}