content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.metrics;
  
  import com.google.common.collect.EvictingQueue;
  
  /**
   * Represents a time series which can be graphed in the UI.
   */
  public class TimeSeries {
    private final String mName;
    private final EvictingQueue<DataPoint> mDataPoints;
  
    /**
     * Create a new time series with the given name and no data.
     * @param name name of the time series
     */
    public TimeSeries(String name) {
      mName = name;
      mDataPoints = EvictingQueue.create(20);
    }
  
    /**
     * Record a value at the current time.
     * @param value value to record
     */
    public void record(double value) {
      mDataPoints.add(new DataPoint(value));
    }
  
    /**
     * @return the name of the time series
     */
    public String getName() {
      return mName;
    }
  
    /**
     * @return the data of the time series
     */
    public EvictingQueue<DataPoint> getDataPoints() {
      return mDataPoints;
    }
  
    /**
     * Represents a datapoint in a time series. Millisecond epoch time is used for the timestamp.
     */
    public final class DataPoint {
      private final long mTimestamp;
      private final double mValue;
  
      /**
       * Construct a new data point with the current time as the timestamp.
       * @param value the value of the data point
       */
      public DataPoint(double value) {
        mTimestamp = System.currentTimeMillis();
        mValue = value;
      }
  
      /**
       * @return the timestamp of the data point in milliseconds epoch time
       */
      public long getTimeStamp() {
        return mTimestamp;
      }
  
      /**
       * @return the value of the data point
       */
      public double getValue() {
        return mValue;
      }
    }
  }
  