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.quotas;
019
020import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
021import org.apache.yetus.audience.InterfaceAudience;
022import org.apache.yetus.audience.InterfaceStability;
023
024/**
025 * This limiter will refill resources at every TimeUnit/resources interval. For example: For a
026 * limiter configured with 10resources/second, then 1 resource will be refilled after every 100ms
027 * (1sec/10resources)
028 */
029@InterfaceAudience.Private
030@InterfaceStability.Evolving
031public class AverageIntervalRateLimiter extends RateLimiter {
032  private long nextRefillTime = -1L;
033
034  @Override
035  public long refill(long limit) {
036    final long now = EnvironmentEdgeManager.currentTime();
037    if (nextRefillTime == -1) {
038      // Till now no resource has been consumed.
039      nextRefillTime = EnvironmentEdgeManager.currentTime();
040      return limit;
041    }
042
043    long timeInterval = now - nextRefillTime;
044    long delta = 0;
045    long timeUnitInMillis = super.getTimeUnitInMillis();
046    if (timeInterval >= timeUnitInMillis) {
047      delta = limit;
048    } else if (timeInterval > 0) {
049      double r = ((double) timeInterval / (double) timeUnitInMillis) * limit;
050      delta = (long) r;
051    }
052
053    if (delta > 0) {
054      this.nextRefillTime = now;
055    }
056
057    return delta;
058  }
059
060  @Override
061  public long getWaitInterval(long limit, long available, long amount) {
062    if (nextRefillTime == -1) {
063      return 0;
064    }
065
066    double r = ((double) (amount - available)) * super.getTimeUnitInMillis() / limit;
067    return (long) r;
068  }
069
070  // This method is for strictly testing purpose only
071  @Override
072  public void setNextRefillTime(long nextRefillTime) {
073    this.nextRefillTime = nextRefillTime;
074  }
075
076  @Override
077  public long getNextRefillTime() {
078    return this.nextRefillTime;
079  }
080
081}