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.util.Iterator; 22 23 import org.apache.hadoop.classification.InterfaceAudience; 24 25 /** 26 * Block cache interface. Anything that implements the {@link Cacheable} 27 * interface can be put in the cache. 28 */ 29 @InterfaceAudience.Private 30 public interface BlockCache extends Iterable<CachedBlock> { 31 /** 32 * Add block to cache. 33 * @param cacheKey The block's cache key. 34 * @param buf The block contents wrapped in a ByteBuffer. 35 * @param inMemory Whether block should be treated as in-memory 36 */ 37 void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory); 38 39 /** 40 * Add block to cache (defaults to not in-memory). 41 * @param cacheKey The block's cache key. 42 * @param buf The object to cache. 43 */ 44 void cacheBlock(BlockCacheKey cacheKey, Cacheable buf); 45 46 /** 47 * Fetch block from cache. 48 * @param cacheKey Block to fetch. 49 * @param caching Whether this request has caching enabled (used for stats) 50 * @param repeat Whether this is a repeat lookup for the same block 51 * (used to avoid double counting cache misses when doing double-check locking) 52 * @param updateCacheMetrics Whether to update cache metrics or not 53 * @return Block or null if block is not in 2 cache. 54 */ 55 Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat, 56 boolean updateCacheMetrics); 57 58 /** 59 * Evict block from cache. 60 * @param cacheKey Block to evict 61 * @return true if block existed and was evicted, false if not 62 */ 63 boolean evictBlock(BlockCacheKey cacheKey); 64 65 /** 66 * Evicts all blocks for the given HFile. 67 * 68 * @return the number of blocks evicted 69 */ 70 int evictBlocksByHfileName(String hfileName); 71 72 /** 73 * Get the statistics for this block cache. 74 * @return Stats 75 */ 76 CacheStats getStats(); 77 78 /** 79 * Shutdown the cache. 80 */ 81 void shutdown(); 82 83 /** 84 * Returns the total size of the block cache, in bytes. 85 * @return size of cache, in bytes 86 */ 87 long size(); 88 89 /** 90 * Returns the free size of the block cache, in bytes. 91 * @return free space in cache, in bytes 92 */ 93 long getFreeSize(); 94 95 /** 96 * Returns the occupied size of the block cache, in bytes. 97 * @return occupied space in cache, in bytes 98 */ 99 long getCurrentSize(); 100 101 /** 102 * Returns the number of blocks currently cached in the block cache. 103 * @return number of blocks in the cache 104 */ 105 long getBlockCount(); 106 107 /** 108 * @return Iterator over the blocks in the cache. 109 */ 110 Iterator<CachedBlock> iterator(); 111 112 /** 113 * @return The list of sub blockcaches that make up this one; returns null if no sub caches. 114 */ 115 BlockCache [] getBlockCaches(); 116 }