Fixes #2020 - Introduce a name for `HttpClient` instances.

Added HttpClientMBean, and overridden getObjectContextBasis() so that
the HttpClient name is inherited by children components such as the
HttpClientTransport, the ThreadPool, etc.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-client/pom.xml

@@ -99,6 +99,12 @@
       <artifactId>jetty-io</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.eclipse.jetty</groupId>
+      <artifactId>jetty-jmx</artifactId>
+      <version>${project.version}</version>
+      <optional>true</optional>
+    </dependency>
 
     <dependency>
       <groupId>org.eclipse.jetty</groupId>

jetty-client/src/main/java/org/eclipse/jetty/client/HttpClient.java

@@ -146,6 +146,7 @@ public class HttpClient extends ContainerLifeCycle
     private HttpField encodingField;
     private boolean removeIdleDestinations = false;
     private boolean connectBlocking = false;
+    private String name = getClass().getSimpleName() + "@" + Integer.toHexString(hashCode());
 
     /**
      * Creates a {@link HttpClient} instance that can perform requests to non-TLS destinations only
@@ -196,8 +197,6 @@ public class HttpClient extends ContainerLifeCycle
         if (sslContextFactory != null)
             addBean(sslContextFactory);
 
-        String name = HttpClient.class.getSimpleName() + "@" + hashCode();
-
         if (executor == null)
         {
             QueuedThreadPool threadPool = new QueuedThreadPool();
@@ -639,6 +638,17 @@ public class HttpClient extends ContainerLifeCycle
         this.byteBufferPool = byteBufferPool;
     }
 
+    @ManagedAttribute("The name of this HttpClient")
+    public String getName()
+    {
+        return name;
+    }
+
+    public void setName(String name)
+    {
+        this.name = name;
+    }
+
     /**
      * @return the max time, in milliseconds, a connection can take to connect to destinations
      */

jetty-client/src/main/java/org/eclipse/jetty/client/jmx/HttpClientMBean.java

@@ -0,0 +1,40 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.client.jmx;
+
+import org.eclipse.jetty.client.HttpClient;
+import org.eclipse.jetty.jmx.ObjectMBean;
+
+public class HttpClientMBean extends ObjectMBean
+{
+    public HttpClientMBean(Object managedObject)
+    {
+        super(managedObject);
+    }
+
+    @Override
+    public String getObjectContextBasis()
+    {
+        // Returning the HttpClient name as the "context" property
+        // because it is inherited by the ObjectNames of the components
+        // of HttpClient such as the transport, the threadpool, etc.
+        HttpClient httpClient = (HttpClient)getManagedObject();
+        return httpClient.getName();
+    }
+}

jetty-client/src/test/java/org/eclipse/jetty/client/jmx/HttpClientJMXTest.java

@@ -0,0 +1,51 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.client.jmx;
+
+import java.lang.management.ManagementFactory;
+import java.util.Locale;
+import java.util.Set;
+
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+
+import org.eclipse.jetty.client.HttpClient;
+import org.eclipse.jetty.jmx.MBeanContainer;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class HttpClientJMXTest
+{
+    @Test
+    public void testHttpClientName() throws Exception
+    {
+        MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
+        MBeanContainer mbeanContainer = new MBeanContainer(mbeanServer);
+        HttpClient httpClient = new HttpClient();
+        httpClient.addBean(mbeanContainer);
+        httpClient.start();
+
+        String domain = HttpClient.class.getPackage().getName();
+        ObjectName pattern = new ObjectName(domain + ":type=" + HttpClient.class.getSimpleName().toLowerCase(Locale.ENGLISH) + ",*");
+        Set<ObjectName> objectNames = mbeanServer.queryNames(pattern, null);
+        Assert.assertEquals(1, objectNames.size());
+        ObjectName objectName = objectNames.iterator().next();
+        Assert.assertEquals(httpClient.getName(), objectName.getKeyProperty("context"));
+    }
+}