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.io.hfile; 019 020import org.apache.hadoop.conf.Configuration; 021import org.apache.yetus.audience.InterfaceAudience; 022 023/** 024 * An on heap block cache implementation extended LruBlockCache and only cache index block. This 025 * block cache should be only used by {@link org.apache.hadoop.hbase.client.ClientSideRegionScanner} 026 * that normally considers to be used by client resides out of the region server, e.g. a container 027 * of a map reduce job. 028 **/ 029@InterfaceAudience.Private 030public class IndexOnlyLruBlockCache extends LruBlockCache { 031 032 public IndexOnlyLruBlockCache(long maxSize, long blockSize, boolean evictionThread, 033 Configuration conf) { 034 super(maxSize, blockSize, evictionThread, conf); 035 } 036 037 /** 038 * Cache only index block with the specified name and buffer 039 * @param cacheKey block's cache key 040 * @param buf block buffer 041 * @param inMemory if block is in-memory 042 */ 043 @Override 044 public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory) { 045 if (isMetaBlock(buf.getBlockType())) { 046 super.cacheBlock(cacheKey, buf, inMemory); 047 } 048 } 049}