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 */
018package org.apache.hadoop.metrics2.util;
019
020import java.lang.management.ManagementFactory;
021
022import javax.management.InstanceAlreadyExistsException;
023import javax.management.MBeanServer;
024import javax.management.ObjectName;
025
026import org.apache.commons.logging.Log;
027import org.apache.commons.logging.LogFactory;
028import org.apache.hadoop.classification.InterfaceAudience;
029import org.apache.hadoop.classification.InterfaceStability;
030import 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
039public 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}