/**
    * 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 org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.metrics.Interns;
  import org.apache.hadoop.hbase.util.FastLongHistogram;
  import org.apache.hadoop.metrics2.MetricHistogram;
  import org.apache.hadoop.metrics2.MetricsInfo;
  import org.apache.hadoop.metrics2.MetricsRecordBuilder;
  /**
   * Extended histogram implementation with metric range counters.
   */
  @InterfaceAudience.Private
  public abstract class MutableRangeHistogram extends MutableHistogram implements MetricHistogram {
  
    public MutableRangeHistogram(MetricsInfo info) {
      this(info.name(), info.description());
    }
  
    public MutableRangeHistogram(String name, String description) {
      this(name, description, Integer.MAX_VALUE << 2);
    }
  
    public MutableRangeHistogram(String name, String description, long expectedMax) {
      super(name, description, expectedMax);
    }
  
    /**
     * Returns the type of range histogram size or time 
     */
    public abstract String getRangeType();
    
    /**
     * Returns the ranges to be counted 
     */
    public abstract long[] getRanges();
  
    
    @Override
    public synchronized void snapshot(MetricsRecordBuilder metricsRecordBuilder, boolean all) {
      // Get a reference to the old histogram.
      FastLongHistogram histo = histogram.reset();
      if (histo != null) {
        updateSnapshotMetrics(metricsRecordBuilder, histo);
        updateSnapshotRangeMetrics(metricsRecordBuilder, histo);
      }
    }
  
    public void updateSnapshotRangeMetrics(MetricsRecordBuilder metricsRecordBuilder,
                                           FastLongHistogram histogram) {
      long priorRange = 0;
      long cumNum = 0;
  
      final long[] ranges = getRanges();
      final String rangeType = getRangeType();
      for (int i = 0; i < ranges.length - 1; i++) {
        long val = histogram.getNumAtOrBelow(ranges[i]);
        if (val - cumNum > 0) {
          metricsRecordBuilder.addCounter(
              Interns.info(name + "_" + rangeType + "_" + priorRange + "-" + ranges[i], desc),
              val - cumNum);
        }
        priorRange = ranges[i];
        cumNum = val;
      }
      long val = histogram.getCount();
      if (val - cumNum > 0) {
        metricsRecordBuilder.addCounter(
            Interns.info(name + "_" + rangeType + "_" + ranges[ranges.length - 1] + "-inf", desc),
            val - cumNum);
      }
    }  
  }