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.DataOutputStream;
20 import java.io.IOException;
21
22 import org.apache.hadoop.hbase.classification.InterfaceAudience;
23 import org.apache.hadoop.hbase.Cell;
24 import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
25 import org.apache.hadoop.hbase.io.encoding.HFileBlockDecodingContext;
26 import org.apache.hadoop.hbase.io.encoding.HFileBlockEncodingContext;
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 * Starts encoding for a block of KeyValues. Call
41 * {@link #endBlockEncoding(HFileBlockEncodingContext, DataOutputStream, byte[], BlockType)}
42 * to finish encoding of a block.
43 * @param encodingCtx
44 * @param out
45 * @throws IOException
46 */
47 void startBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out)
48 throws IOException;
49
50 /**
51 * Encodes a KeyValue.
52 * @param cell
53 * @param encodingCtx
54 * @param out
55 * @return unencoded kv size
56 * @throws IOException
57 */
58 int encode(Cell cell, HFileBlockEncodingContext encodingCtx, DataOutputStream out)
59 throws IOException;
60
61 /**
62 * Ends encoding for a block of KeyValues. Gives a chance for the encoder to do the finishing
63 * stuff for the encoded block. It must be called at the end of block encoding.
64 * @param encodingCtx
65 * @param out
66 * @param uncompressedBytesWithHeader
67 * @param blockType
68 * @throws IOException
69 */
70 void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out,
71 byte[] uncompressedBytesWithHeader, BlockType blockType) throws IOException;
72
73 /**
74 * Decides whether we should use a scanner over encoded blocks.
75 * @return Whether to use encoded scanner.
76 */
77 boolean useEncodedScanner();
78
79 /**
80 * Save metadata in HFile which will be written to disk
81 * @param writer writer for a given HFile
82 * @exception IOException on disk problems
83 */
84 void saveMetadata(HFile.Writer writer)
85 throws IOException;
86
87 /** @return the data block encoding */
88 DataBlockEncoding getDataBlockEncoding();
89
90 /**
91 * @return the effective in-cache data block encoding, taking into account
92 * whether we are doing a compaction.
93 */
94 public DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction);
95
96 /**
97 * Create an encoder specific encoding context object for writing. And the
98 * encoding context should also perform compression if compressionAlgorithm is
99 * valid.
100 *
101 * @param headerBytes header bytes
102 * @param fileContext HFile meta data
103 * @return a new {@link HFileBlockEncodingContext} object
104 */
105 HFileBlockEncodingContext newDataBlockEncodingContext(byte[] headerBytes,
106 HFileContext fileContext);
107
108 /**
109 * create a encoder specific decoding context for reading. And the
110 * decoding context should also do decompression if compressionAlgorithm
111 * is valid.
112 *
113 * @param fileContext - HFile meta data
114 * @return a new {@link HFileBlockDecodingContext} object
115 */
116 HFileBlockDecodingContext newDataBlockDecodingContext(HFileContext fileContext);
117 }