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    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
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    *
   *     http://www.apache.org/licenses/LICENSE-2.0
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   * Unless required by applicable law or agreed to in writing, software
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  package org.apache.hadoop.hbase.io.hfile;
  
  import static org.junit.Assert.assertEquals;
  
  import org.apache.hadoop.hbase.io.hfile.CombinedBlockCache.CombinedCacheStats;
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  @Category({SmallTests.class})
  public class TestCombinedBlockCache {
    @Test
    public void testCombinedCacheStats() {
      CacheStats lruCacheStats = new CacheStats("lruCacheStats", 2);
      CacheStats bucketCacheStats = new CacheStats("bucketCacheStats", 2);
      CombinedCacheStats stats =
          new CombinedCacheStats(lruCacheStats, bucketCacheStats);
      
      double delta = 0.01;
      
      // period 1:
      // lru cache: 1 hit caching, 1 miss caching
      // bucket cache: 2 hit non-caching,1 miss non-caching/primary,1 fail insert
      lruCacheStats.hit(true);
      lruCacheStats.miss(true);
      bucketCacheStats.hit(false);
      bucketCacheStats.hit(false);
      bucketCacheStats.miss(false);
      
      assertEquals(5, stats.getRequestCount());
      assertEquals(2, stats.getRequestCachingCount());
      assertEquals(2, stats.getMissCount());
      assertEquals(1, stats.getMissCachingCount());
      assertEquals(3, stats.getHitCount());
      assertEquals(1, stats.getHitCachingCount());
      assertEquals(0.6, stats.getHitRatio(), delta);
      assertEquals(0.5, stats.getHitCachingRatio(), delta);
      assertEquals(0.4, stats.getMissRatio(), delta);
      assertEquals(0.5, stats.getMissCachingRatio(), delta);
      
      
      // lru cache: 2 evicted, 1 evict
      // bucket cache: 1 evict
      lruCacheStats.evicted(1000);
      lruCacheStats.evicted(1000);
      lruCacheStats.evict();
      bucketCacheStats.evict();
      assertEquals(2, stats.getEvictionCount());
      assertEquals(2, stats.getEvictedCount());
      assertEquals(1.0, stats.evictedPerEviction(), delta);
      
      // rollMetricsPeriod
      stats.rollMetricsPeriod();
      assertEquals(3, stats.getSumHitCountsPastNPeriods());
      assertEquals(5, stats.getSumRequestCountsPastNPeriods());
      assertEquals(1, stats.getSumHitCachingCountsPastNPeriods());
      assertEquals(2, stats.getSumRequestCachingCountsPastNPeriods());
      assertEquals(0.6, stats.getHitRatioPastNPeriods(), delta);
      assertEquals(0.5, stats.getHitCachingRatioPastNPeriods(), delta);
      
      // period 2:
      // lru cache: 3 hit caching
      lruCacheStats.hit(true);
      lruCacheStats.hit(true);
      lruCacheStats.hit(true);
      stats.rollMetricsPeriod();
      assertEquals(6, stats.getSumHitCountsPastNPeriods());
      assertEquals(8, stats.getSumRequestCountsPastNPeriods());
      assertEquals(4, stats.getSumHitCachingCountsPastNPeriods());
      assertEquals(5, stats.getSumRequestCachingCountsPastNPeriods());
      assertEquals(0.75, stats.getHitRatioPastNPeriods(), delta);
      assertEquals(0.8, stats.getHitCachingRatioPastNPeriods(), delta);
    }
  }