1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.channel;
17
18 import io.netty.util.ReferenceCounted;
19
20 import java.io.IOException;
21 import java.nio.channels.FileChannel;
22 import java.nio.channels.WritableByteChannel;
23
24 /**
25 * A region of a file that is sent via a {@link Channel} which supports
26 * <a href="https://en.wikipedia.org/wiki/Zero-copy">zero-copy file transfer</a>.
27 *
28 * <h3>Upgrade your JDK / JRE</h3>
29 *
30 * {@link FileChannel#transferTo(long, long, WritableByteChannel)} has at least
31 * four known bugs in the old versions of Sun JDK and perhaps its derived ones.
32 * Please upgrade your JDK to 1.6.0_18 or later version if you are going to use
33 * zero-copy file transfer.
34 * <ul>
35 * <li><a href="https://bugs.java.com/bugdatabase/view_bug.do?bug_id=5103988">5103988</a>
36 * - FileChannel.transferTo() should return -1 for EAGAIN instead throws IOException</li>
37 * <li><a href="https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6253145">6253145</a>
38 * - FileChannel.transferTo() on Linux fails when going beyond 2GB boundary</li>
39 * <li><a href="https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6427312">6427312</a>
40 * - FileChannel.transferTo() throws IOException "system call interrupted"</li>
41 * <li><a href="https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6524172">6470086</a>
42 * - FileChannel.transferTo(2147483647, 1, channel) causes "Value too large" exception</li>
43 * </ul>
44 *
45 * <h3>Check your operating system and JDK / JRE</h3>
46 *
47 * If your operating system (or JDK / JRE) does not support zero-copy file
48 * transfer, sending a file with {@link FileRegion} might fail or yield worse
49 * performance. For example, sending a large file doesn't work well in Windows.
50 *
51 * <h3>Not all transports support it</h3>
52 */
53 public interface FileRegion extends ReferenceCounted {
54
55 /**
56 * Returns the offset in the file where the transfer began.
57 */
58 long position();
59
60 /**
61 * Returns the bytes which was transferred already.
62 *
63 * @deprecated Use {@link #transferred()} instead.
64 */
65 @Deprecated
66 long transfered();
67
68 /**
69 * Returns the bytes which was transferred already.
70 */
71 long transferred();
72
73 /**
74 * Returns the number of bytes to transfer.
75 */
76 long count();
77
78 /**
79 * Transfers the content of this file region to the specified channel.
80 *
81 * @param target the destination of the transfer
82 * @param position the relative offset of the file where the transfer
83 * begins from. For example, <tt>0</tt> will make the
84 * transfer start from {@link #position()}th byte and
85 * <tt>{@link #count()} - 1</tt> will make the last
86 * byte of the region transferred.
87 */
88 long transferTo(WritableByteChannel target, long position) throws IOException;
89
90 @Override
91 FileRegion retain();
92
93 @Override
94 FileRegion retain(int increment);
95
96 @Override
97 FileRegion touch();
98
99 @Override
100 FileRegion touch(Object hint);
101 }
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