content: /*
   * 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 com.alibaba.metrics;
  
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.junit.runners.Parameterized;
  import org.junit.runners.Parameterized.Parameters;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.concurrent.TimeUnit;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.assertj.core.api.Assertions.offset;
  
  @RunWith(value = Parameterized.class)
  public class MeterApproximationTest {
  
      @Parameters
      public static Collection<Object[]> ratesPerMinute() {
          Object[][] data = new Object[][] {
              { 15 }, { 60 }, { 600 }, { 6000 }
          };
          return Arrays.asList(data);
      }
  
      private final long ratePerMinute;
  
      public MeterApproximationTest(long ratePerMinute) {
          this.ratePerMinute = ratePerMinute;
      }
  
      @Test
      public void controlMeter1MinuteMeanApproximation() throws Exception {
          final Meter meter = simulateMetronome(
                  62934, TimeUnit.MILLISECONDS,
                  3, TimeUnit.MINUTES);
  
          assertThat(meter.getOneMinuteRate()*60.0)
                  .isEqualTo(ratePerMinute, offset(0.1*ratePerMinute));
      }
  
      @Test
      public void controlMeter5MinuteMeanApproximation() throws Exception {
          final Meter meter = simulateMetronome(
                  62934, TimeUnit.MILLISECONDS,
                  13, TimeUnit.MINUTES);
  
          assertThat(meter.getFiveMinuteRate()*60.0)
                  .isEqualTo(ratePerMinute, offset(0.1*ratePerMinute));
      }
  
      @Test
      public void controlMeter15MinuteMeanApproximation() throws Exception {
          final Meter meter = simulateMetronome(
                  62934, TimeUnit.MILLISECONDS,
                  38, TimeUnit.MINUTES);
  
          assertThat(meter.getFifteenMinuteRate()*60.0)
                  .isEqualTo(ratePerMinute, offset(0.1*ratePerMinute));
      }
  
      private Meter simulateMetronome(
              long introDelay, TimeUnit introDelayUnit,
              long duration, TimeUnit durationUnit) {
  
          final ManualClock clock = new ManualClock();
          final Meter meter = new MeterImpl(clock);
  
          clock.addNanos(introDelayUnit.toNanos(introDelay));
  
          final long endTick = clock.getTick() + durationUnit.toNanos(duration);
          final long marksIntervalInNanos = TimeUnit.MINUTES.toNanos(1) / ratePerMinute;
  
          while (clock.getTick() <= endTick) {
              clock.addNanos(marksIntervalInNanos);
              meter.mark();
          }
  
          return meter;
      }
  
  }
  