1 | /** |
---|
2 | * Licensed to the Apache Software Foundation (ASF) under one |
---|
3 | * or more contributor license agreements. See the NOTICE file |
---|
4 | * distributed with this work for additional information |
---|
5 | * regarding copyright ownership. The ASF licenses this file |
---|
6 | * to you under the Apache License, Version 2.0 (the |
---|
7 | * "License"); you may not use this file except in compliance |
---|
8 | * with the License. You may obtain a copy of the License at |
---|
9 | * |
---|
10 | * http://www.apache.org/licenses/LICENSE-2.0 |
---|
11 | * |
---|
12 | * Unless required by applicable law or agreed to in writing, software |
---|
13 | * distributed under the License is distributed on an "AS IS" BASIS, |
---|
14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
---|
15 | * See the License for the specific language governing permissions and |
---|
16 | * limitations under the License. |
---|
17 | */ |
---|
18 | |
---|
19 | package org.apache.hadoop.io; |
---|
20 | |
---|
21 | import java.io.IOException; |
---|
22 | import java.io.DataInput; |
---|
23 | import java.io.DataOutput; |
---|
24 | |
---|
25 | import org.apache.commons.logging.Log; |
---|
26 | import org.apache.commons.logging.LogFactory; |
---|
27 | |
---|
28 | /** |
---|
29 | * A byte sequence that is usable as a key or value. |
---|
30 | * It is resizable and distinguishes between the size of the seqeunce and |
---|
31 | * the current capacity. The hash function is the front of the md5 of the |
---|
32 | * buffer. The sort order is the same as memcmp. |
---|
33 | */ |
---|
34 | public class BytesWritable extends BinaryComparable |
---|
35 | implements WritableComparable<BinaryComparable> { |
---|
36 | private static final Log LOG = LogFactory.getLog(BytesWritable.class); |
---|
37 | private static final int LENGTH_BYTES = 4; |
---|
38 | private static final byte[] EMPTY_BYTES = {}; |
---|
39 | |
---|
40 | private int size; |
---|
41 | private byte[] bytes; |
---|
42 | |
---|
43 | /** |
---|
44 | * Create a zero-size sequence. |
---|
45 | */ |
---|
46 | public BytesWritable() {this(EMPTY_BYTES);} |
---|
47 | |
---|
48 | /** |
---|
49 | * Create a BytesWritable using the byte array as the initial value. |
---|
50 | * @param bytes This array becomes the backing storage for the object. |
---|
51 | */ |
---|
52 | public BytesWritable(byte[] bytes) { |
---|
53 | this.bytes = bytes; |
---|
54 | this.size = bytes.length; |
---|
55 | } |
---|
56 | |
---|
57 | /** |
---|
58 | * Get the data from the BytesWritable. |
---|
59 | * @return The data is only valid between 0 and getLength() - 1. |
---|
60 | */ |
---|
61 | public byte[] getBytes() { |
---|
62 | return bytes; |
---|
63 | } |
---|
64 | |
---|
65 | /** |
---|
66 | * Get the data from the BytesWritable. |
---|
67 | * @deprecated Use {@link #getBytes()} instead. |
---|
68 | */ |
---|
69 | @Deprecated |
---|
70 | public byte[] get() { |
---|
71 | return getBytes(); |
---|
72 | } |
---|
73 | |
---|
74 | /** |
---|
75 | * Get the current size of the buffer. |
---|
76 | */ |
---|
77 | public int getLength() { |
---|
78 | return size; |
---|
79 | } |
---|
80 | |
---|
81 | /** |
---|
82 | * Get the current size of the buffer. |
---|
83 | * @deprecated Use {@link #getLength()} instead. |
---|
84 | */ |
---|
85 | @Deprecated |
---|
86 | public int getSize() { |
---|
87 | return getLength(); |
---|
88 | } |
---|
89 | |
---|
90 | /** |
---|
91 | * Change the size of the buffer. The values in the old range are preserved |
---|
92 | * and any new values are undefined. The capacity is changed if it is |
---|
93 | * necessary. |
---|
94 | * @param size The new number of bytes |
---|
95 | */ |
---|
96 | public void setSize(int size) { |
---|
97 | if (size > getCapacity()) { |
---|
98 | setCapacity(size * 3 / 2); |
---|
99 | } |
---|
100 | this.size = size; |
---|
101 | } |
---|
102 | |
---|
103 | /** |
---|
104 | * Get the capacity, which is the maximum size that could handled without |
---|
105 | * resizing the backing storage. |
---|
106 | * @return The number of bytes |
---|
107 | */ |
---|
108 | public int getCapacity() { |
---|
109 | return bytes.length; |
---|
110 | } |
---|
111 | |
---|
112 | /** |
---|
113 | * Change the capacity of the backing storage. |
---|
114 | * The data is preserved. |
---|
115 | * @param new_cap The new capacity in bytes. |
---|
116 | */ |
---|
117 | public void setCapacity(int new_cap) { |
---|
118 | if (new_cap != getCapacity()) { |
---|
119 | byte[] new_data = new byte[new_cap]; |
---|
120 | if (new_cap < size) { |
---|
121 | size = new_cap; |
---|
122 | } |
---|
123 | if (size != 0) { |
---|
124 | System.arraycopy(bytes, 0, new_data, 0, size); |
---|
125 | } |
---|
126 | bytes = new_data; |
---|
127 | } |
---|
128 | } |
---|
129 | |
---|
130 | /** |
---|
131 | * Set the BytesWritable to the contents of the given newData. |
---|
132 | * @param newData the value to set this BytesWritable to. |
---|
133 | */ |
---|
134 | public void set(BytesWritable newData) { |
---|
135 | set(newData.bytes, 0, newData.size); |
---|
136 | } |
---|
137 | |
---|
138 | /** |
---|
139 | * Set the value to a copy of the given byte range |
---|
140 | * @param newData the new values to copy in |
---|
141 | * @param offset the offset in newData to start at |
---|
142 | * @param length the number of bytes to copy |
---|
143 | */ |
---|
144 | public void set(byte[] newData, int offset, int length) { |
---|
145 | setSize(0); |
---|
146 | setSize(length); |
---|
147 | System.arraycopy(newData, offset, bytes, 0, size); |
---|
148 | } |
---|
149 | |
---|
150 | // inherit javadoc |
---|
151 | public void readFields(DataInput in) throws IOException { |
---|
152 | setSize(0); // clear the old data |
---|
153 | setSize(in.readInt()); |
---|
154 | in.readFully(bytes, 0, size); |
---|
155 | } |
---|
156 | |
---|
157 | // inherit javadoc |
---|
158 | public void write(DataOutput out) throws IOException { |
---|
159 | out.writeInt(size); |
---|
160 | out.write(bytes, 0, size); |
---|
161 | } |
---|
162 | |
---|
163 | public int hashCode() { |
---|
164 | return super.hashCode(); |
---|
165 | } |
---|
166 | |
---|
167 | /** |
---|
168 | * Are the two byte sequences equal? |
---|
169 | */ |
---|
170 | public boolean equals(Object right_obj) { |
---|
171 | if (right_obj instanceof BytesWritable) |
---|
172 | return super.equals(right_obj); |
---|
173 | return false; |
---|
174 | } |
---|
175 | |
---|
176 | /** |
---|
177 | * Generate the stream of bytes as hex pairs separated by ' '. |
---|
178 | */ |
---|
179 | public String toString() { |
---|
180 | StringBuffer sb = new StringBuffer(3*size); |
---|
181 | for (int idx = 0; idx < size; idx++) { |
---|
182 | // if not the first, put a blank separator in |
---|
183 | if (idx != 0) { |
---|
184 | sb.append(' '); |
---|
185 | } |
---|
186 | String num = Integer.toHexString(0xff & bytes[idx]); |
---|
187 | // if it is only one digit, add a leading 0. |
---|
188 | if (num.length() < 2) { |
---|
189 | sb.append('0'); |
---|
190 | } |
---|
191 | sb.append(num); |
---|
192 | } |
---|
193 | return sb.toString(); |
---|
194 | } |
---|
195 | |
---|
196 | /** A Comparator optimized for BytesWritable. */ |
---|
197 | public static class Comparator extends WritableComparator { |
---|
198 | public Comparator() { |
---|
199 | super(BytesWritable.class); |
---|
200 | } |
---|
201 | |
---|
202 | /** |
---|
203 | * Compare the buffers in serialized form. |
---|
204 | */ |
---|
205 | public int compare(byte[] b1, int s1, int l1, |
---|
206 | byte[] b2, int s2, int l2) { |
---|
207 | return compareBytes(b1, s1+LENGTH_BYTES, l1-LENGTH_BYTES, |
---|
208 | b2, s2+LENGTH_BYTES, l2-LENGTH_BYTES); |
---|
209 | } |
---|
210 | } |
---|
211 | |
---|
212 | static { // register this comparator |
---|
213 | WritableComparator.define(BytesWritable.class, new Comparator()); |
---|
214 | } |
---|
215 | |
---|
216 | } |
---|