1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with this
4 * work for additional information regarding copyright ownership. The ASF
5 * licenses this file to you under the Apache License, Version 2.0 (the
6 * "License"); you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
13 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
14 * License for the specific language governing permissions and limitations
15 * under the License.
16 */
17 package org.apache.hadoop.hbase.io.hfile;
18
19 import java.io.IOException;
20 import java.nio.ByteBuffer;
21
22 import org.apache.hadoop.classification.InterfaceAudience;
23 import org.apache.hadoop.hbase.io.compress.Compression.Algorithm;
24 import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
25 import org.apache.hadoop.hbase.io.encoding.HFileBlockEncodingContext;
26 import org.apache.hadoop.hbase.io.encoding.HFileBlockDecodingContext;
27 import org.apache.hadoop.hbase.util.Bytes;
28
29 /**
30 * Controls what kind of data block encoding is used. If data block encoding is
31 * not set or the given block is not a data block (encoded or not), methods
32 * should just return the unmodified block.
33 */
34 @InterfaceAudience.Private
35 public interface HFileDataBlockEncoder {
36 /** Type of encoding used for data blocks in HFile. Stored in file info. */
37 byte[] DATA_BLOCK_ENCODING = Bytes.toBytes("DATA_BLOCK_ENCODING");
38
39 /**
40 * Should be called before an encoded or unencoded data block is written to
41 * disk.
42 * @param in KeyValues next to each other
43 * @param encodingResult the encoded result
44 * @param blockType block type
45 * @throws IOException
46 */
47 void beforeWriteToDisk(
48 ByteBuffer in,
49 boolean includesMemstoreTS,
50 HFileBlockEncodingContext encodingResult,
51 BlockType blockType
52 ) throws IOException;
53
54 /**
55 * Decides whether we should use a scanner over encoded blocks.
56 * @return Whether to use encoded scanner.
57 */
58 boolean useEncodedScanner();
59
60 /**
61 * Save metadata in HFile which will be written to disk
62 * @param writer writer for a given HFile
63 * @exception IOException on disk problems
64 */
65 void saveMetadata(HFile.Writer writer)
66 throws IOException;
67
68 /** @return the data block encoding */
69 DataBlockEncoding getDataBlockEncoding();
70
71 /**
72 * Create an encoder specific encoding context object for writing. And the
73 * encoding context should also perform compression if compressionAlgorithm is
74 * valid.
75 *
76 * @param compressionAlgorithm compression algorithm
77 * @param headerBytes header bytes
78 * @return a new {@link HFileBlockEncodingContext} object
79 */
80 HFileBlockEncodingContext newDataBlockEncodingContext(
81 Algorithm compressionAlgorithm, byte[] headerBytes
82 );
83
84 /**
85 * create a encoder specific decoding context for reading. And the
86 * decoding context should also do decompression if compressionAlgorithm
87 * is valid.
88 *
89 * @param compressionAlgorithm
90 * @return a new {@link HFileBlockDecodingContext} object
91 */
92 HFileBlockDecodingContext newDataBlockDecodingContext(
93 Algorithm compressionAlgorithm
94 );
95 }