hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/InclusiveCombinedBlockCache.java

/*
 * 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;

import org.apache.yetus.audience.InterfaceAudience;

@InterfaceAudience.Private
public class InclusiveCombinedBlockCache extends CombinedBlockCache {
  public InclusiveCombinedBlockCache(FirstLevelBlockCache l1, BlockCache l2) {
    super(l1, l2);
    l1.setVictimCache(l2);
  }

  @Override
  public Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat,
    boolean updateCacheMetrics) {
    // On all external cache set ups the lru should have the l2 cache set as the victimHandler
    // Because of that all requests that miss inside of the lru block cache will be
    // tried in the l2 block cache.
    return l1Cache.getBlock(cacheKey, caching, repeat, updateCacheMetrics);
  }

  /**
   * @param cacheKey The block's cache key.
   * @param buf      The block contents wrapped in a ByteBuffer.
   * @param inMemory Whether block should be treated as in-memory. This parameter is only useful for
   *                 the L1 lru cache.
   */
  @Override
  public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory) {
    // This is the inclusive part of the combined block cache.
    // Every block is placed into both block caches.
    l1Cache.cacheBlock(cacheKey, buf, inMemory);

    // This assumes that insertion into the L2 block cache is either async or very fast.
    l2Cache.cacheBlock(cacheKey, buf, inMemory);
  }

  @Override
  public boolean evictBlock(BlockCacheKey cacheKey) {
    boolean l1Result = this.l1Cache.evictBlock(cacheKey);
    boolean l2Result = this.l2Cache.evictBlock(cacheKey);
    return l1Result || l2Result;
  }
}