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 package org.apache.hadoop.hbase.io;
19
20 import java.io.InputStream;
21 import java.nio.ByteBuffer;
22
23 import org.apache.hadoop.hbase.classification.InterfaceAudience;
24
25 /**
26 * Not thread safe!
27 * <p>
28 * Please note that the reads will cause position movement on wrapped ByteBuffer.
29 */
30 @InterfaceAudience.Private
31 public class ByteBufferInputStream extends InputStream {
32
33 private ByteBuffer buf;
34
35 public ByteBufferInputStream(ByteBuffer buf) {
36 this.buf = buf;
37 }
38
39 /**
40 * Reads the next byte of data from this input stream. The value byte is returned as an
41 * <code>int</code> in the range <code>0</code> to <code>255</code>. If no byte is available
42 * because the end of the stream has been reached, the value <code>-1</code> is returned.
43 * @return the next byte of data, or <code>-1</code> if the end of the stream has been reached.
44 */
45 public int read() {
46 if (this.buf.hasRemaining()) {
47 return (this.buf.get() & 0xff);
48 }
49 return -1;
50 }
51
52 /**
53 * Reads up to next <code>len</code> bytes of data from buffer into passed array(starting from
54 * given offset).
55 * @param b the array into which the data is read.
56 * @param off the start offset in the destination array <code>b</code>
57 * @param len the maximum number of bytes to read.
58 * @return the total number of bytes actually read into the buffer, or <code>-1</code> if not even
59 * 1 byte can be read because the end of the stream has been reached.
60 */
61 public int read(byte b[], int off, int len) {
62 int avail = available();
63 if (avail <= 0) {
64 return -1;
65 }
66
67 if (len > avail) {
68 len = avail;
69 }
70 if (len <= 0) {
71 return 0;
72 }
73
74 this.buf.get(b, off, len);
75 return len;
76 }
77
78 /**
79 * Skips <code>n</code> bytes of input from this input stream. Fewer bytes might be skipped if the
80 * end of the input stream is reached. The actual number <code>k</code> of bytes to be skipped is
81 * equal to the smaller of <code>n</code> and remaining bytes in the stream.
82 * @param n the number of bytes to be skipped.
83 * @return the actual number of bytes skipped.
84 */
85 public long skip(long n) {
86 long k = Math.min(n, available());
87 if (k < 0) {
88 k = 0;
89 }
90 this.buf.position((int) (this.buf.position() + k));
91 return k;
92 }
93
94 /**
95 * @return the number of remaining bytes that can be read (or skipped
96 * over) from this input stream.
97 */
98 public int available() {
99 return this.buf.remaining();
100 }
101 }