001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.hadoop.metrics2.util;
019
020 import java.lang.management.ManagementFactory;
021
022 import javax.management.InstanceAlreadyExistsException;
023 import javax.management.MBeanServer;
024 import javax.management.ObjectName;
025
026 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028 import org.apache.hadoop.classification.InterfaceAudience;
029 import org.apache.hadoop.classification.InterfaceStability;
030 import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
031
032 /**
033 * This util class provides a method to register an MBean using
034 * our standard naming convention as described in the doc
035 * for {link {@link #register(String, String, Object)}
036 */
037 @InterfaceAudience.Public
038 @InterfaceStability.Stable
039 public class MBeans {
040 private static final Log LOG = LogFactory.getLog(MBeans.class);
041
042 /**
043 * Register the MBean using our standard MBeanName format
044 * "hadoop:service=<serviceName>,name=<nameName>"
045 * Where the <serviceName> and <nameName> are the supplied parameters
046 *
047 * @param serviceName
048 * @param nameName
049 * @param theMbean - the MBean to register
050 * @return the named used to register the MBean
051 */
052 static public ObjectName register(String serviceName, String nameName,
053 Object theMbean) {
054 final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
055 ObjectName name = getMBeanName(serviceName, nameName);
056 try {
057 mbs.registerMBean(theMbean, name);
058 LOG.debug("Registered "+ name);
059 return name;
060 } catch (InstanceAlreadyExistsException iaee) {
061 if (LOG.isTraceEnabled()) {
062 LOG.trace("Failed to register MBean \""+ name + "\"", iaee);
063 } else {
064 LOG.warn("Failed to register MBean \""+ name
065 + "\": Instance already exists.");
066 }
067 } catch (Exception e) {
068 LOG.warn("Failed to register MBean \""+ name + "\"", e);
069 }
070 return null;
071 }
072
073 static public void unregister(ObjectName mbeanName) {
074 LOG.debug("Unregistering "+ mbeanName);
075 final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
076 if (mbeanName == null) {
077 LOG.debug("Stacktrace: ", new Throwable());
078 return;
079 }
080 try {
081 mbs.unregisterMBean(mbeanName);
082 } catch (Exception e) {
083 LOG.warn("Error unregistering "+ mbeanName, e);
084 }
085 DefaultMetricsSystem.removeMBeanName(mbeanName);
086 }
087
088 static private ObjectName getMBeanName(String serviceName, String nameName) {
089 ObjectName name = null;
090 String nameStr = "Hadoop:service="+ serviceName +",name="+ nameName;
091 try {
092 name = DefaultMetricsSystem.newMBeanName(nameStr);
093 } catch (Exception e) {
094 LOG.warn("Error creating MBean object name: "+ nameStr, e);
095 }
096 return name;
097 }
098 }