/**
    * 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.hbase.regionserver.throttle;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.ScheduledChore;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.regionserver.RegionServerServices;
  import org.apache.hadoop.hbase.regionserver.compactions.OffPeakHours;
  
  /**
   * A throughput controller which uses the follow schema to limit throughput
   * <ul>
   * <li>If flush pressure is greater than or equal to 1.0, no limitation.</li>
   * <li>In normal case, the max throughput is tuned between
   * {@value #HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_LOWER_BOUND} and
   * {@value #HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_UPPER_BOUND}, using the formula &quot;lower +
   * (upper - lower) * flushPressure&quot;, where flushPressure is in range [0.0, 1.0)</li>
   * </ul>
   * @see org.apache.hadoop.hbase.regionserver.HRegionServer#getFlushPressure()
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
  public class PressureAwareFlushThroughputController extends PressureAwareThroughputController {
  
    private static final Log LOG = LogFactory.getLog(PressureAwareFlushThroughputController.class);
  
    public static final String HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_UPPER_BOUND =
        "hbase.hstore.flush.throughput.upper.bound";
  
    private static final long DEFAULT_HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_UPPER_BOUND =
        200L * 1024 * 1024;
  
    public static final String HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_LOWER_BOUND =
        "hbase.hstore.flush.throughput.lower.bound";
  
    private static final long DEFAULT_HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_LOWER_BOUND =
        100L * 1024 * 1024;
  
    public static final String HBASE_HSTORE_FLUSH_THROUGHPUT_TUNE_PERIOD =
        "hbase.hstore.flush.throughput.tune.period";
  
    private static final int DEFAULT_HSTORE_FLUSH_THROUGHPUT_TUNE_PERIOD = 20 * 1000;
  
    // check flush throughput every this size
    public static final String HBASE_HSTORE_FLUSH_THROUGHPUT_CONTROL_CHECK_INTERVAL =
        "hbase.hstore.flush.throughput.control.check.interval";
  
    private static final long DEFAULT_HBASE_HSTORE_FLUSH_THROUGHPUT_CONTROL_CHECK_INTERVAL =
        10L * 1024 * 1024;// 10MB
  
    @Override
    public void setup(final RegionServerServices server) {
      server.getChoreService().scheduleChore(
        new ScheduledChore("FlushThroughputTuner", this, tuningPeriod, this.tuningPeriod) {
  
          @Override
          protected void chore() {
            tune(server.getFlushPressure());
          }
        });
    }
  
    private void tune(double flushPressure) {
      double maxThroughputToSet;
      if (flushPressure >= 1.0) {
        // set to unlimited if global memstore size already exceeds lower limit
        maxThroughputToSet = Double.MAX_VALUE;
      } else {
        // flushPressure is between 0.0 and 1.0, we use a simple linear formula to
        // calculate the throughput limitation.
        maxThroughputToSet =
            maxThroughputLowerBound + (maxThroughputUpperBound - maxThroughputLowerBound)
                * flushPressure;
      }
      if (LOG.isDebugEnabled()) {
        LOG.debug("flushPressure is " + flushPressure + ", tune flush throughput to "
            + throughputDesc(maxThroughputToSet));
      }
      this.setMaxThroughput(maxThroughputToSet);
    }
  
   @Override
   public void setConf(Configuration conf) {
     super.setConf(conf);
     if (conf == null) {
       return;
     }
     this.maxThroughputUpperBound =
         conf.getLong(HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_UPPER_BOUND,
           DEFAULT_HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_UPPER_BOUND);
     this.maxThroughputLowerBound =
         conf.getLong(HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_LOWER_BOUND,
           DEFAULT_HBASE_HSTORE_FLUSH_MAX_THROUGHPUT_LOWER_BOUND);
     this.offPeakHours = OffPeakHours.getInstance(conf);
     this.controlPerSize =
         conf.getLong(HBASE_HSTORE_FLUSH_THROUGHPUT_CONTROL_CHECK_INTERVAL,
           DEFAULT_HBASE_HSTORE_FLUSH_THROUGHPUT_CONTROL_CHECK_INTERVAL);
     this.setMaxThroughput(this.maxThroughputLowerBound);
     this.tuningPeriod =
         getConf().getInt(HBASE_HSTORE_FLUSH_THROUGHPUT_TUNE_PERIOD,
           DEFAULT_HSTORE_FLUSH_THROUGHPUT_TUNE_PERIOD);
     LOG.info("Flush throughput configurations, upper bound: "
         + throughputDesc(maxThroughputUpperBound) + ", lower bound "
         + throughputDesc(maxThroughputLowerBound) + ", tuning period: " + tuningPeriod + " ms");
   }
 
   @Override
   public String toString() {
     return "DefaultFlushController [maxThroughput=" + throughputDesc(getMaxThroughput())
         + ", activeFlushNumber=" + activeOperations.size() + "]";
   }
 }