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.hbase.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 * @param cacheDataInL1 If multi-tier block cache deploy -- i.e. has an L1 and L2 tier -- then
37 * if this flag is true, cache data blocks up in the L1 tier (meta blocks are probably being
38 * cached in L1 already).
39 */
40 void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory, boolean cacheDataInL1);
41
42 /**
43 * Add block to cache (defaults to not in-memory).
44 * @param cacheKey The block's cache key.
45 * @param buf The object to cache.
46 */
47 void cacheBlock(BlockCacheKey cacheKey, Cacheable buf);
48
49 /**
50 * Fetch block from cache.
51 * @param cacheKey Block to fetch.
52 * @param caching Whether this request has caching enabled (used for stats)
53 * @param repeat Whether this is a repeat lookup for the same block
54 * (used to avoid double counting cache misses when doing double-check locking)
55 * @param updateCacheMetrics Whether to update cache metrics or not
56 * @return Block or null if block is not in 2 cache.
57 */
58 Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat,
59 boolean updateCacheMetrics);
60
61 /**
62 * Evict block from cache.
63 * @param cacheKey Block to evict
64 * @return true if block existed and was evicted, false if not
65 */
66 boolean evictBlock(BlockCacheKey cacheKey);
67
68 /**
69 * Evicts all blocks for the given HFile.
70 *
71 * @return the number of blocks evicted
72 */
73 int evictBlocksByHfileName(String hfileName);
74
75 /**
76 * Get the statistics for this block cache.
77 * @return Stats
78 */
79 CacheStats getStats();
80
81 /**
82 * Shutdown the cache.
83 */
84 void shutdown();
85
86 /**
87 * Returns the total size of the block cache, in bytes.
88 * @return size of cache, in bytes
89 */
90 long size();
91
92 /**
93 * Returns the free size of the block cache, in bytes.
94 * @return free space in cache, in bytes
95 */
96 long getFreeSize();
97
98 /**
99 * Returns the occupied size of the block cache, in bytes.
100 * @return occupied space in cache, in bytes
101 */
102 long getCurrentSize();
103
104 /**
105 * Returns the number of blocks currently cached in the block cache.
106 * @return number of blocks in the cache
107 */
108 long getBlockCount();
109
110 /**
111 * @return Iterator over the blocks in the cache.
112 */
113 Iterator<CachedBlock> iterator();
114
115 /**
116 * @return The list of sub blockcaches that make up this one; returns null if no sub caches.
117 */
118 BlockCache [] getBlockCaches();
119 }