/**
    * 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.metrics2.lib;
  
  import static org.junit.Assert.assertEquals;
  
  import org.apache.hadoop.hbase.testclassification.MetricsTests;
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.apache.hadoop.metrics2.AbstractMetric;
  import org.apache.hadoop.metrics2.MetricsRecord;
  import org.apache.hadoop.metrics2.impl.MetricsCollectorImpl;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  import java.util.ArrayList;
  import java.util.List;
  
  @Category({ MetricsTests.class, SmallTests.class })
  public class TestMutableRangeHistogram {
  
    private static final String RECORD_NAME = "test";
    private static final String SIZE_HISTOGRAM_NAME = "TestSize";
  
    /**
     * calculate the distribution for last bucket, see HBASE-24615 for detail.
     */
    @Test
    public void testLastBucketWithSizeHistogram() {
      // create and init histogram minValue and maxValue
      MetricsCollectorImpl collector = new MetricsCollectorImpl();
      MutableSizeHistogram histogram = new MutableSizeHistogram(SIZE_HISTOGRAM_NAME, "");
      long[] ranges = histogram.getRanges();
      int len = ranges.length;
      histogram.add(0L);
      histogram.add(ranges[len - 1]);
      histogram.snapshot(collector.addRecord(RECORD_NAME), true);
      collector.clear();
  
      // fill up values and snapshot
      histogram.add(ranges[len - 2] * 2);
      histogram.add(ranges[len - 1] * 2);
      histogram.snapshot(collector.addRecord(RECORD_NAME), true);
      List<? extends MetricsRecord> records = collector.getRecords();
      assertEquals(1, records.size());
      MetricsRecord record = records.iterator().next();
      assertEquals(RECORD_NAME, record.name());
  
      // get size range metrics
      String histogramMetricPrefix = SIZE_HISTOGRAM_NAME + "_" + histogram.getRangeType();
      List<AbstractMetric> metrics = new ArrayList<>();
      for (AbstractMetric metric : record.metrics()) {
        if (metric.name().startsWith(histogramMetricPrefix)) {
          metrics.add(metric);
        }
      }
      assertEquals(2, metrics.size());
  
      // check range [10000000,100000000]
      String metricName = histogramMetricPrefix + "_" + ranges[len - 2] + "-" + ranges[len - 1];
      assertEquals(metricName, metrics.get(0).name());
      assertEquals(1, metrics.get(0).value().longValue());
  
      // check range [100000000, inf]
      metricName = histogramMetricPrefix + "_" + ranges[len - 1] + "-inf";
      assertEquals(metricName, metrics.get(1).name(), metricName);
      assertEquals(1, metrics.get(1).value().longValue());
    }
  }