001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.metrics2;
019
020import org.apache.yetus.audience.InterfaceAudience;
021
022/**
023 * Metrics Histogram interface. Implementing classes will expose computed quartile values through
024 * the metrics system.
025 */
026@InterfaceAudience.Private
027public interface MetricHistogram {
028
029  // Strings used to create metrics names.
030  String NUM_OPS_METRIC_NAME = "_num_ops";
031  String MIN_METRIC_NAME = "_min";
032  String MAX_METRIC_NAME = "_max";
033  String MEAN_METRIC_NAME = "_mean";
034  String MEDIAN_METRIC_NAME = "_median";
035  String TWENTY_FIFTH_PERCENTILE_METRIC_NAME = "_25th_percentile";
036  String SEVENTY_FIFTH_PERCENTILE_METRIC_NAME = "_75th_percentile";
037  String NINETIETH_PERCENTILE_METRIC_NAME = "_90th_percentile";
038  String NINETY_FIFTH_PERCENTILE_METRIC_NAME = "_95th_percentile";
039  String NINETY_EIGHTH_PERCENTILE_METRIC_NAME = "_98th_percentile";
040  String NINETY_NINETH_PERCENTILE_METRIC_NAME = "_99th_percentile";
041  String NINETY_NINE_POINT_NINETH_PERCENTILE_METRIC_NAME = "_99.9th_percentile";
042
043  /**
044   * Add a single value to a histogram's stream of values.
045   */
046  void add(long value);
047
048  /**
049   * Return the total number of values added to the histogram.
050   * @return the total number of values.
051   */
052  long getCount();
053
054}