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 * @param updateCacheMetrics Whether to update cache metrics or not 55 * @return Block or null if block is not in 2 cache. 56 */ 57 Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat, 58 boolean updateCacheMetrics); 59 60 /** 61 * Evict block from cache. 62 * @param cacheKey Block to evict 63 * @return true if block existed and was evicted, false if not 64 */ 65 boolean evictBlock(BlockCacheKey cacheKey); 66 67 /** 68 * Evicts all blocks for the given HFile. 69 * 70 * @return the number of blocks evicted 71 */ 72 int evictBlocksByHfileName(String hfileName); 73 74 /** 75 * Get the statistics for this block cache. 76 * @return Stats 77 */ 78 CacheStats getStats(); 79 80 /** 81 * Shutdown the cache. 82 */ 83 void shutdown(); 84 85 /** 86 * Returns the total size of the block cache, in bytes. 87 * @return size of cache, in bytes 88 */ 89 long size(); 90 91 /** 92 * Returns the free size of the block cache, in bytes. 93 * @return free space in cache, in bytes 94 */ 95 long getFreeSize(); 96 97 /** 98 * Returns the occupied size of the block cache, in bytes. 99 * @return occupied space in cache, in bytes 100 */ 101 long getCurrentSize(); 102 103 /** 104 * Returns the number of blocks that have been evicted. 105 * @return number of evicted blocks 106 */ 107 long getEvictedCount(); 108 109 /** 110 * Returns the number of blocks currently cached in the block cache. 111 * @return number of blocks in the cache 112 */ 113 long getBlockCount(); 114 115 /** 116 * Performs a BlockCache summary and returns a List of BlockCacheColumnFamilySummary objects. 117 * This method could be fairly heavyweight in that it evaluates the entire HBase file-system 118 * against what is in the RegionServer BlockCache. 119 * <br><br> 120 * The contract of this interface is to return the List in sorted order by Table name, then 121 * ColumnFamily. 122 * 123 * @param conf HBaseConfiguration 124 * @return List of BlockCacheColumnFamilySummary 125 * @throws IOException exception 126 */ 127 List<BlockCacheColumnFamilySummary> getBlockCacheColumnFamilySummaries(Configuration conf) throws IOException; 128 }