/**
 * 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 org.apache.hadoop.classification.InterfaceAudience;


/**
 * 
 * This is the JMX management interface for the RPC layer.
 * Many of the statistics are sampled and averaged on an interval 
 * which can be specified in the metrics config file.
 * <p>
 * For the statistics that are sampled and averaged, one must specify 
 * a metrics context that does periodic update calls. Most 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
 *
 */
@InterfaceAudience.Private
public interface RpcMgtMBean {
  
  /**
   * Number of RPC Operations in the last interval
   * @return number of operations
   */
  int getRpcOpsNumber();
  
  /**
   * Average time for RPC Operations in last interval
   * @return time in msec
   */
  long getRpcOpsAvgProcessingTime();
  
  /**
   * The Minimum RPC Operation Processing Time since reset was called
   * @return time in msec
   */
  long getRpcOpsAvgProcessingTimeMin();
  
  
  /**
   * The Maximum RPC Operation Processing Time since reset was called
   * @return time in msec
   */
  long getRpcOpsAvgProcessingTimeMax();
  
  
  /**
   * The Average RPC Operation Queued Time in the last interval
   * @return time in msec
   */
  long getRpcOpsAvgQueueTime();
  
  
  /**
   * The Minimum RPC Operation Queued Time since reset was called
   * @return time in msec
   */
  long getRpcOpsAvgQueueTimeMin();
  
  /**
   * The Maximum RPC Operation Queued Time since reset was called
   * @return time in msec
   */
  long getRpcOpsAvgQueueTimeMax();
  
  /**
   * Reset all min max times
   */
  void resetAllMinMax();
  
  /**
   * The number of open RPC conections
   * @return the number of open rpc connections
   */
  public int getNumOpenConnections();
  
  /**
   * The number of rpc calls in the queue.
   * @return The number of rpc calls in the queue.
   */
  public int getCallQueueLen();
}