/**
 * 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.mapreduce;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.Writable;

/**
 * Status information on the current state of the Map-Reduce cluster.
 * 
 * <p><code>ClusterMetrics</code> provides clients with information such as:
 * <ol>
 *   <li>
 *   Size of the cluster.  
 *   </li>
 *   <li>
 *   Number of blacklisted and decommissioned trackers.  
 *   </li>
 *   <li>
 *   Slot capacity of the cluster. 
 *   </li>
 *   <li>
 *   The number of currently occupied/reserved map & reduce slots.
 *   </li>
 *   <li>
 *   The number of currently running map & reduce tasks.
 *   </li>
 *   <li>
 *   The number of job submissions.
 *   </li>
 * </ol></p>
 * 
 * <p>Clients can query for the latest <code>ClusterMetrics</code>, via 
 * {@link Cluster#getClusterStatus()}.</p>
 * 
 * @see Cluster
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class ClusterMetrics implements Writable {
  private int runningMaps;
  private int runningReduces;
  private int occupiedMapSlots;
  private int occupiedReduceSlots;
  private int reservedMapSlots;
  private int reservedReduceSlots;
  private int totalMapSlots;
  private int totalReduceSlots;
  private int totalJobSubmissions;
  private int numTrackers;
  private int numBlacklistedTrackers;
  private int numDecommissionedTrackers;

  public ClusterMetrics() {
  }
  
  public ClusterMetrics(int runningMaps, int runningReduces,
      int occupiedMapSlots, int occupiedReduceSlots,
      int reservedMapSlots, int reservedReduceSlots,
      int mapSlots, int reduceSlots, 
      int totalJobSubmissions,
      int numTrackers, int numBlacklistedTrackers,
      int numDecommissionedNodes) {
    this.runningMaps = runningMaps;
    this.runningReduces = runningReduces;
    this.occupiedMapSlots = occupiedMapSlots;
    this.occupiedReduceSlots = occupiedReduceSlots;
    this.reservedMapSlots = reservedMapSlots;
    this.reservedReduceSlots = reservedReduceSlots;
    this.totalMapSlots = mapSlots;
    this.totalReduceSlots = reduceSlots;
    this.totalJobSubmissions = totalJobSubmissions;
    this.numTrackers = numTrackers;
    this.numBlacklistedTrackers = numBlacklistedTrackers;
    this.numDecommissionedTrackers = numDecommissionedNodes;
  }

  /**
   * Get the number of running map tasks in the cluster.
   * 
   * @return running maps
   */
  public int getRunningMaps() {
    return runningMaps;
  }
  
  /**
   * Get the number of running reduce tasks in the cluster.
   * 
   * @return running reduces
   */
  public int getRunningReduces() {
    return runningReduces;
  }
  
  /**
   * Get number of occupied map slots in the cluster.
   * 
   * @return occupied map slot count
   */
  public int getOccupiedMapSlots() { 
    return occupiedMapSlots;
  }
  
  /**
   * Get the number of occupied reduce slots in the cluster.
   * 
   * @return occupied reduce slot count
   */
  public int getOccupiedReduceSlots() { 
    return occupiedReduceSlots; 
  }

  /**
   * Get number of reserved map slots in the cluster.
   * 
   * @return reserved map slot count
   */
  public int getReservedMapSlots() { 
    return reservedMapSlots;
  }
  
  /**
   * Get the number of reserved reduce slots in the cluster.
   * 
   * @return reserved reduce slot count
   */
  public int getReservedReduceSlots() { 
    return reservedReduceSlots; 
  }

  /**
   * Get the total number of map slots in the cluster.
   * 
   * @return map slot capacity
   */
  public int getMapSlotCapacity() {
    return totalMapSlots;
  }
  
  /**
   * Get the total number of reduce slots in the cluster.
   * 
   * @return reduce slot capacity
   */
  public int getReduceSlotCapacity() {
    return totalReduceSlots;
  }
  
  /**
   * Get the total number of job submissions in the cluster.
   * 
   * @return total number of job submissions
   */
  public int getTotalJobSubmissions() {
    return totalJobSubmissions;
  }
  
  /**
   * Get the number of active trackers in the cluster.
   * 
   * @return active tracker count.
   */
  public int getTaskTrackerCount() {
    return numTrackers;
  }
  
  /**
   * Get the number of blacklisted trackers in the cluster.
   * 
   * @return blacklisted tracker count
   */
  public int getBlackListedTaskTrackerCount() {
    return numBlacklistedTrackers;
  }
  
  /**
   * Get the number of decommissioned trackers in the cluster.
   * 
   * @return decommissioned tracker count
   */
  public int getDecommissionedTaskTrackerCount() {
    return numDecommissionedTrackers;
  }

  @Override
  public void readFields(DataInput in) throws IOException {
    runningMaps = in.readInt();
    runningReduces = in.readInt();
    occupiedMapSlots = in.readInt();
    occupiedReduceSlots = in.readInt();
    reservedMapSlots = in.readInt();
    reservedReduceSlots = in.readInt();
    totalMapSlots = in.readInt();
    totalReduceSlots = in.readInt();
    totalJobSubmissions = in.readInt();
    numTrackers = in.readInt();
    numBlacklistedTrackers = in.readInt();
    numDecommissionedTrackers = in.readInt();
  }

  @Override
  public void write(DataOutput out) throws IOException {
    out.writeInt(runningMaps);
    out.writeInt(runningReduces);
    out.writeInt(occupiedMapSlots);
    out.writeInt(occupiedReduceSlots);
    out.writeInt(reservedMapSlots);
    out.writeInt(reservedReduceSlots);
    out.writeInt(totalMapSlots);
    out.writeInt(totalReduceSlots);
    out.writeInt(totalJobSubmissions);
    out.writeInt(numTrackers);
    out.writeInt(numBlacklistedTrackers);
    out.writeInt(numDecommissionedTrackers);
  }

}