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.hbase.metrics;
019
020import org.apache.hadoop.hbase.HBaseInterfaceAudience;
021import org.apache.yetus.audience.InterfaceAudience;
022import org.apache.yetus.audience.InterfaceStability;
023
024/**
025 * A metric which measure the rate at which some operation is invoked.
026 */
027@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
028@InterfaceStability.Evolving
029public interface Meter extends Metric {
030
031  /**
032   * Records one occurrence.
033   */
034  void mark();
035
036  /**
037   * Records {@code events} occurrences.
038   * @param events Number of occurrences to record.
039   */
040  void mark(long events);
041
042  /**
043   * Returns the number of events.
044   * @return the number of events.
045   */
046  long getCount();
047
048  /**
049   * Returns the mean rate at which events have occurred since the meter was created.
050   * @return the mean rate at which events have occurred since the meter was created
051   */
052  double getMeanRate();
053
054  /**
055   * Returns the one-minute exponentially-weighted moving average rate at which events have occurred
056   * since the meter was created.
057   * <p/>
058   * This rate has the same exponential decay factor as the one-minute load average in the {@code
059   * top} Unix command.
060   * @return the one-minute exponentially-weighted moving average rate at which events have occurred
061   *         since the meter was created
062   */
063  double getOneMinuteRate();
064
065  /**
066   * Returns the five-minute exponentially-weighted moving average rate at which events have
067   * occurred since the meter was created.
068   * <p/>
069   * This rate has the same exponential decay factor as the five-minute load average in the {@code
070   * top} Unix command.
071   * @return the five-minute exponentially-weighted moving average rate at which events have
072   *         occurred since the meter was created
073   */
074  double getFiveMinuteRate();
075
076  /**
077   * Returns the fifteen-minute exponentially-weighted moving average rate at which events have
078   * occurred since the meter was created.
079   * <p/>
080   * This rate has the same exponential decay factor as the fifteen-minute load average in the
081   * {@code top} Unix command.
082   * @return the fifteen-minute exponentially-weighted moving average rate at which events have
083   *         occurred since the meter was created
084   */
085  double getFifteenMinuteRate();
086}