/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.ipc.metrics;

import javax.management.ObjectName;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.metrics.util.MBeanUtil;
import org.apache.hadoop.metrics.util.MetricsDynamicMBeanBase;
import org.apache.hadoop.metrics.util.MetricsRegistry;


/**
 * 
 * This is the JMX MBean for reporting the RPC layer Activity.
 * The MBean is register using the name
 *        "hadoop:service=<RpcServiceName>,name=RpcActivityForPort<port>"
 * 
 * Many of the activity metrics are sampled and averaged on an interval 
 * which can be specified in the metrics config file.
 * <p>
 * For the metrics that are sampled and averaged, one must specify 
 * a metrics context that does periodic update calls. Most metrics contexts do.
 * The default Null metrics context however does NOT. So if you aren't
 * using any other metrics context then you can turn on the viewing and averaging
 * of sampled metrics by  specifying the following two lines
 *  in the hadoop-meterics.properties file:
 *  <pre>
 *        rpc.class=org.apache.hadoop.metrics.spi.NullContextWithUpdateThread
 *        rpc.period=10
 *  </pre>
 *<p>
 * Note that the metrics are collected regardless of the context used.
 * The context with the update thread is used to average the data periodically
 *
 *
 *
 * Impl details: We use a dynamic mbean that gets the list of the metrics
 * from the metrics registry passed as an argument to the constructor
 */
@InterfaceAudience.Private
public class RpcActivityMBean extends MetricsDynamicMBeanBase {
  private final ObjectName mbeanName;

  /**
   * 
   * @param mr - the metrics registry that has all the metrics
   * @param serviceName - the service name for the rpc service 
   * @param port - the rpc port.
   */
  public RpcActivityMBean(final MetricsRegistry mr, final String serviceName,
      final String port) {
    super(mr, "Rpc layer statistics");
    mbeanName = MBeanUtil.registerMBean(serviceName,
          "RpcActivityForPort" + port, this);
  }
  

  public void shutdown() {
    if (mbeanName != null)
      MBeanUtil.unregisterMBean(mbeanName);
  }
}