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.encoding;
18
19 import java.io.IOException;
20 import java.nio.ByteBuffer;
21
22 import org.apache.hadoop.hbase.io.compress.Compression;
23
24 /**
25 * A decoding context that is created by a reader's encoder, and is shared
26 * across the reader's all read operations.
27 *
28 * @see HFileBlockEncodingContext for encoding
29 */
30 public interface HFileBlockDecodingContext {
31
32 /**
33 * @return the compression algorithm used by this decoding context
34 */
35 Compression.Algorithm getCompression();
36
37 /**
38 * Perform all actions that need to be done before the encoder's real decoding process.
39 * Decompression needs to be done if {@link #getCompression()} returns a valid compression
40 * algorithm.
41 *
42 * @param onDiskSizeWithoutHeader numBytes after block and encoding headers
43 * @param uncompressedSizeWithoutHeader numBytes without header required to store the block after
44 * decompressing (not decoding)
45 * @param blockBufferWithoutHeader ByteBuffer pointed after the header but before the data
46 * @param onDiskBlock on disk bytes to be decoded
47 * @param offset data start offset in onDiskBlock
48 * @throws IOException
49 */
50 void prepareDecoding(
51 int onDiskSizeWithoutHeader,
52 int uncompressedSizeWithoutHeader,
53 ByteBuffer blockBufferWithoutHeader,
54 byte[] onDiskBlock,
55 int offset
56 ) throws IOException;
57
58 }