/**
 * 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.mapred;

import org.apache.hadoop.metrics.MetricsContext;
import org.apache.hadoop.metrics.MetricsRecord;
import org.apache.hadoop.metrics.MetricsUtil;
import org.apache.hadoop.metrics.Updater;
import org.apache.hadoop.metrics.jvm.JvmMetrics;

@SuppressWarnings("deprecation")
class LocalJobRunnerMetrics implements Updater {
  private final MetricsRecord metricsRecord;

  private int numMapTasksLaunched = 0;
  private int numMapTasksCompleted = 0;
  private int numReduceTasksLaunched = 0;
  private int numReduceTasksCompleted = 0;
  private int numWaitingMaps = 0;
  private int numWaitingReduces = 0;
  
  public LocalJobRunnerMetrics(JobConf conf) {
    String sessionId = conf.getSessionId();
    // Initiate JVM Metrics
    JvmMetrics.init("JobTracker", sessionId);
    // Create a record for map-reduce metrics
    MetricsContext context = MetricsUtil.getContext("mapred");
    // record name is jobtracker for compatibility 
    metricsRecord = MetricsUtil.createRecord(context, "jobtracker");
    metricsRecord.setTag("sessionId", sessionId);
    context.registerUpdater(this);
  }
    
  /**
   * Since this object is a registered updater, this method will be called
   * periodically, e.g. every 5 seconds.
   */
  public void doUpdates(MetricsContext unused) {
    synchronized (this) {
      metricsRecord.incrMetric("maps_launched", numMapTasksLaunched);
      metricsRecord.incrMetric("maps_completed", numMapTasksCompleted);
      metricsRecord.incrMetric("reduces_launched", numReduceTasksLaunched);
      metricsRecord.incrMetric("reduces_completed", numReduceTasksCompleted);
      metricsRecord.incrMetric("waiting_maps", numWaitingMaps);
      metricsRecord.incrMetric("waiting_reduces", numWaitingReduces);

      numMapTasksLaunched = 0;
      numMapTasksCompleted = 0;
      numReduceTasksLaunched = 0;
      numReduceTasksCompleted = 0;
      numWaitingMaps = 0;
      numWaitingReduces = 0;
    }
    metricsRecord.update();
  }

  public synchronized void launchMap(TaskAttemptID taskAttemptID) {
    ++numMapTasksLaunched;
    decWaitingMaps(taskAttemptID.getJobID(), 1);
  }

  public synchronized void completeMap(TaskAttemptID taskAttemptID) {
    ++numMapTasksCompleted;
  }

  public synchronized void launchReduce(TaskAttemptID taskAttemptID) {
    ++numReduceTasksLaunched;
    decWaitingReduces(taskAttemptID.getJobID(), 1);
  }

  public synchronized void completeReduce(TaskAttemptID taskAttemptID) {
    ++numReduceTasksCompleted;
  }

  private synchronized void decWaitingMaps(JobID id, int task) {
    numWaitingMaps -= task;
  }
  
  private synchronized void decWaitingReduces(JobID id, int task){
    numWaitingReduces -= task;
  }

}