1 /** 2 * 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, 15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 package org.apache.hadoop.hbase.io.hfile; 20 21 import java.io.IOException; 22 import java.util.List; 23 24 import org.apache.hadoop.classification.InterfaceAudience; 25 import org.apache.hadoop.conf.Configuration; 26 27 /** 28 * Block cache interface. Anything that implements the {@link Cacheable} 29 * interface can be put in the cache. 30 */ 31 @InterfaceAudience.Private 32 public interface BlockCache { 33 /** 34 * Add block to cache. 35 * @param cacheKey The block's cache key. 36 * @param buf The block contents wrapped in a ByteBuffer. 37 * @param inMemory Whether block should be treated as in-memory 38 */ 39 void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory); 40 41 /** 42 * Add block to cache (defaults to not in-memory). 43 * @param cacheKey The block's cache key. 44 * @param buf The object to cache. 45 */ 46 void cacheBlock(BlockCacheKey cacheKey, Cacheable buf); 47 48 /** 49 * Fetch block from cache. 50 * @param cacheKey Block to fetch. 51 * @param caching Whether this request has caching enabled (used for stats) 52 * @param repeat Whether this is a repeat lookup for the same block 53 * (used to avoid double counting cache misses when doing double-check locking) 54 * @return Block or null if block is not in 2 cache. 55 * @see HFileReaderV2#readBlock(long, long, boolean, boolean, boolean, BlockType) 56 */ 57 Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat); 58 59 /** 60 * Evict block from cache. 61 * @param cacheKey Block to evict 62 * @return true if block existed and was evicted, false if not 63 */ 64 boolean evictBlock(BlockCacheKey cacheKey); 65 66 /** 67 * Evicts all blocks for the given HFile. 68 * 69 * @return the number of blocks evicted 70 */ 71 int evictBlocksByHfileName(String hfileName); 72 73 /** 74 * Get the statistics for this block cache. 75 * @return Stats 76 */ 77 CacheStats getStats(); 78 79 /** 80 * Shutdown the cache. 81 */ 82 void shutdown(); 83 84 /** 85 * Returns the total size of the block cache, in bytes. 86 * @return size of cache, in bytes 87 */ 88 long size(); 89 90 /** 91 * Returns the free size of the block cache, in bytes. 92 * @return free space in cache, in bytes 93 */ 94 long getFreeSize(); 95 96 /** 97 * Returns the occupied size of the block cache, in bytes. 98 * @return occupied space in cache, in bytes 99 */ 100 long getCurrentSize(); 101 102 /** 103 * Returns the number of blocks that have been evicted. 104 * @return number of evicted blocks 105 */ 106 long getEvictedCount(); 107 108 /** 109 * Returns the number of blocks currently cached in the block cache. 110 * @return number of blocks in the cache 111 */ 112 long getBlockCount(); 113 114 /** 115 * Performs a BlockCache summary and returns a List of BlockCacheColumnFamilySummary objects. 116 * This method could be fairly heavyweight in that it evaluates the entire HBase file-system 117 * against what is in the RegionServer BlockCache. 118 * <br><br> 119 * The contract of this interface is to return the List in sorted order by Table name, then 120 * ColumnFamily. 121 * 122 * @param conf HBaseConfiguration 123 * @return List of BlockCacheColumnFamilySummary 124 * @throws IOException exception 125 */ 126 List<BlockCacheColumnFamilySummary> getBlockCacheColumnFamilySummaries(Configuration conf) throws IOException; 127 }