ExtendedMeter.java

/**
 * Copyright 2015 StreamSets Inc.
 *
 * Licensed under 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 com.streamsets.datacollector.metrics;

import com.codahale.metrics.Clock;
import com.codahale.metrics.EWMA;
import com.codahale.metrics.Meter;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;

import static java.lang.Math.exp;

public class ExtendedMeter extends Meter {
  private static final int INTERVAL = 5;
  private static final double SECONDS_PER_MINUTE = 60.0;
  private static final int THIRTY_MINUTES = 30;
  private static final int ONE_HOUR_MINUTES = 60;
  private static final int SIX_HOURS_MINUTES = 6 * 60;
  private static final int TWELVE_HOURS_MINUTES = 12 * 60;
  private static final int TWENTY_HOURS_MINUTES = 24 * 60;

  private static final double M30_ALPHA = 1 - exp(-INTERVAL / SECONDS_PER_MINUTE / THIRTY_MINUTES);
  private static final double H1_ALPHA = 1 - exp(-INTERVAL / SECONDS_PER_MINUTE / ONE_HOUR_MINUTES);
  private static final double H6_ALPHA = 1 - exp(-INTERVAL / SECONDS_PER_MINUTE / SIX_HOURS_MINUTES);
  private static final double H12_ALPHA = 1 - exp(-INTERVAL / SECONDS_PER_MINUTE / TWELVE_HOURS_MINUTES);
  private static final double H24_ALPHA = 1 - exp(-INTERVAL / SECONDS_PER_MINUTE / TWENTY_HOURS_MINUTES);

  private static final long TICK_INTERVAL = TimeUnit.SECONDS.toNanos(5);

  private final EWMA m30Rate;
  private final EWMA h1Rate;
  private final EWMA h6Rate;
  private final EWMA h12Rate;
  private final EWMA h24Rate;

  private final AtomicLong lastTick;
  private final Clock clock;

  public ExtendedMeter() {
    this(Clock.defaultClock());
  }

  public ExtendedMeter(Clock clock) {
    super(clock);
    this.clock = clock;
    this.lastTick = new AtomicLong(this.clock.getTick());
    m30Rate = new EWMA(M30_ALPHA, INTERVAL, TimeUnit.SECONDS);
    h1Rate = new EWMA(H1_ALPHA, INTERVAL, TimeUnit.SECONDS);
    h6Rate = new EWMA(H6_ALPHA, INTERVAL, TimeUnit.SECONDS);
    h12Rate = new EWMA(H12_ALPHA, INTERVAL, TimeUnit.SECONDS);
    h24Rate = new EWMA(H24_ALPHA, INTERVAL, TimeUnit.SECONDS);
  }

  @Override
  public void mark(long n) {
    super.mark(n);
    tickIfNecessary();
    m30Rate.update(n);
    h1Rate.update(n);
    h6Rate.update(n);
    h12Rate.update(n);
    h24Rate.update(n);
  }

  private void tickIfNecessary() {
    final long oldTick = lastTick.get();
    final long newTick = clock.getTick();
    final long age = newTick - oldTick;
    if (age > TICK_INTERVAL) {
      final long newIntervalStartTick = newTick - age % TICK_INTERVAL;
      if (lastTick.compareAndSet(oldTick, newIntervalStartTick)) {
        final long requiredTicks = age / TICK_INTERVAL;
        for (long i = 0; i < requiredTicks; i++) {
          m30Rate.tick();
          h1Rate.tick();
          h6Rate.tick();
          h12Rate.tick();
          h24Rate.tick();
        }
      }
    }
  }

  public double getThirtyMinuteRate() {
    tickIfNecessary();
    return m30Rate.getRate(TimeUnit.SECONDS);
  }

  public double getOneHourRate() {
    tickIfNecessary();
    return h1Rate.getRate(TimeUnit.SECONDS);
  }

  public double getSixHourRate() {
    tickIfNecessary();
    return h6Rate.getRate(TimeUnit.SECONDS);
  }

  public double getTwelveHourRate() {
    tickIfNecessary();
    return h12Rate.getRate(TimeUnit.SECONDS);
  }

  public double getTwentyFourHourRate() {
    tickIfNecessary();
    return h24Rate.getRate(TimeUnit.SECONDS);
  }

}