/**
    * Copyright The Apache Software Foundation
    *
    * 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.io.hfile.bucket;
  
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.io.hfile.CacheStats;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  
  /**
   * Class that implements cache metrics for bucket cache.
   */
  @InterfaceAudience.Private
  public class BucketCacheStats extends CacheStats {
    private final AtomicLong ioHitCount = new AtomicLong(0);
    private final AtomicLong ioHitTime = new AtomicLong(0);
    private final static int nanoTime = 1000000;
    private long lastLogTime = EnvironmentEdgeManager.currentTime();
  
    BucketCacheStats() {
      super("BucketCache");
    }
  
    @Override
    public String toString() {
      return super.toString() + ", ioHitsPerSecond=" + getIOHitsPerSecond() +
        ", ioTimePerHit=" + getIOTimePerHit();
    }
  
    public void ioHit(long time) {
      ioHitCount.incrementAndGet();
      ioHitTime.addAndGet(time);
    }
  
    public long getIOHitsPerSecond() {
      long now = EnvironmentEdgeManager.currentTime();
      long took = (now - lastLogTime) / 1000;
      lastLogTime = now;
      return took == 0? 0: ioHitCount.get() / took;
    }
  
    public double getIOTimePerHit() {
      long time = ioHitTime.get() / nanoTime;
      long count = ioHitCount.get();
      return ((float) time / (float) count);
    }
  
    public void reset() {
      ioHitCount.set(0);
      ioHitTime.set(0);
    }
  }