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.nio.ByteBuffer;
20
21 import org.apache.hadoop.hbase.classification.InterfaceAudience;
22 import org.apache.hadoop.hbase.KeyValue;
23 import org.apache.hadoop.hbase.util.ByteBufferUtils;
24
25 /**
26 * Stores the state of data block encoder at the beginning of new key.
27 */
28 @InterfaceAudience.Private
29 class CompressionState {
30 int keyLength;
31 int valueLength;
32
33 short rowLength;
34 int prevOffset = FIRST_KEY;
35 byte familyLength;
36 int qualifierLength;
37 byte type;
38
39 private final static int FIRST_KEY = -1;
40
41 boolean isFirst() {
42 return prevOffset == FIRST_KEY;
43 }
44
45 /**
46 * Analyze the key and fill the state.
47 * Uses mark() and reset() in ByteBuffer.
48 * @param in Buffer at the position where key starts
49 * @param keyLength Length of key in bytes
50 * @param valueLength Length of values in bytes
51 */
52 void readKey(ByteBuffer in, int keyLength, int valueLength) {
53 readKey(in, keyLength, valueLength, 0, null);
54 }
55
56 /**
57 * Analyze the key and fill the state assuming we know previous state.
58 * Uses mark() and reset() in ByteBuffer to avoid moving the position.
59 * <p>
60 * This method overrides all the fields of this instance, except
61 * {@link #prevOffset}, which is usually manipulated directly by encoders
62 * and decoders.
63 * @param in Buffer at the position where key starts
64 * @param keyLength Length of key in bytes
65 * @param valueLength Length of values in bytes
66 * @param commonPrefix how many first bytes are common with previous KeyValue
67 * @param previousState State from previous KeyValue
68 */
69 void readKey(ByteBuffer in, int keyLength, int valueLength,
70 int commonPrefix, CompressionState previousState) {
71 this.keyLength = keyLength;
72 this.valueLength = valueLength;
73
74 // fill the state
75 in.mark(); // mark beginning of key
76
77 if (commonPrefix < KeyValue.ROW_LENGTH_SIZE) {
78 rowLength = in.getShort();
79 ByteBufferUtils.skip(in, rowLength);
80
81 familyLength = in.get();
82
83 qualifierLength = keyLength - rowLength - familyLength -
84 KeyValue.KEY_INFRASTRUCTURE_SIZE;
85 ByteBufferUtils.skip(in, familyLength + qualifierLength);
86 } else {
87 rowLength = previousState.rowLength;
88 familyLength = previousState.familyLength;
89 qualifierLength = previousState.qualifierLength +
90 keyLength - previousState.keyLength;
91 ByteBufferUtils.skip(in, (KeyValue.ROW_LENGTH_SIZE +
92 KeyValue.FAMILY_LENGTH_SIZE) +
93 rowLength + familyLength + qualifierLength);
94 }
95
96 readTimestamp(in);
97
98 type = in.get();
99
100 in.reset();
101 }
102
103 protected void readTimestamp(ByteBuffer in) {
104 // used in subclasses to add timestamp to state
105 ByteBufferUtils.skip(in, KeyValue.TIMESTAMP_SIZE);
106 }
107
108 void copyFrom(CompressionState state) {
109 keyLength = state.keyLength;
110 valueLength = state.valueLength;
111
112 rowLength = state.rowLength;
113 prevOffset = state.prevOffset;
114 familyLength = state.familyLength;
115 qualifierLength = state.qualifierLength;
116 type = state.type;
117 }
118 }