Provide an extension of the HttpClientRequest API that exposes the request metric.

Motivation:

Sometimes it is necessary to let framework access to underlying metric of an HTTP request in order to reliably and efficiently share state with the metrics implementation.

This is useful for frameworks that build on top of HTTP client and wants to extend metrics reporting beyond Vert.x capabitilies.

Author: vietj

src/main/java/io/vertx/core/http/impl/HttpClientRequestBase.java

@@ -28,7 +28,7 @@
 /**
  * @author <a href="mailto:[email protected]">Julien Viet</a>
  */
-public abstract class HttpClientRequestBase implements HttpClientRequest {
+public abstract class HttpClientRequestBase implements HttpClientRequestInternal {
 
   protected final ContextInternal context;
   protected final HttpClientStream stream;
@@ -76,6 +76,10 @@ protected String authority() {
     }
   }
 
+  public Object metric() {
+    return stream.metric();
+  }
+
   @Override
   public int streamId() {
     return stream.id();

src/main/java/io/vertx/core/http/impl/HttpClientRequestInternal.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2011-2025 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.core.http.impl;
+
+import io.vertx.core.http.HttpClientRequest;
+import io.vertx.core.spi.metrics.ClientMetrics;
+
+/**
+ * Extends to expose internal methods that are necessary for integration.
+ *
+ * @author <a href="mailto:[email protected]">Julien Viet</a>
+ */
+public interface HttpClientRequestInternal extends HttpClientRequest {
+
+  /**
+   * @return the request metric obtained from {@link ClientMetrics} for this request
+   */
+  Object metric();
+
+}

src/test/java/io/vertx/core/http/HttpMetricsTestBase.java

@@ -17,6 +17,7 @@
 import io.vertx.core.VertxOptions;
 import io.vertx.core.buffer.Buffer;
 import io.vertx.core.http.impl.HttpClientImpl;
+import io.vertx.core.http.impl.HttpClientRequestInternal;
 import io.vertx.core.http.impl.HttpServerRequestInternal;
 import io.vertx.core.impl.VertxInternal;
 import io.vertx.core.metrics.MetricsOptions;
@@ -245,6 +246,9 @@ public void testHttpClientLifecycle(boolean implementInit) throws Exception {
       .setPort(HttpTestBase.DEFAULT_HTTP_PORT)
       .setHost("localhost")
       .setURI("/somepath")).onComplete(onSuccess(req -> {
+      if (implementInit) {
+        assertNotNull(((HttpClientRequestInternal)req).metric());
+      }
       req
         .response(onSuccess(resp -> {
           responseBeginLatch.countDown();