-
Notifications
You must be signed in to change notification settings - Fork 70
/
RewindableContentInputStream.java
91 lines (81 loc) · 2.75 KB
/
RewindableContentInputStream.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
/*
* Copyright 2023 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.cloud.storage;
import com.google.cloud.storage.UnbufferedWritableByteChannelSession.UnbufferedWritableByteChannel;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.GatheringByteChannel;
/**
* Facade which makes an instance of {@link RewindableContent} appear as an input stream.
*
* <p>It does this by calling {@link RewindableContent#writeTo(GatheringByteChannel)} on an
* anonymous channel which closes over the read destination.
*/
final class RewindableContentInputStream extends InputStream {
private final RewindableContent content;
RewindableContentInputStream(RewindableContent content) {
this.content = content;
}
@Override
public int read() throws IOException {
byte[] tmp = new byte[1];
int read = read(tmp);
if (read == -1) {
return -1;
} else {
return tmp[0] & 0xFF;
}
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
// define a byte buffer as the destination for our write
ByteBuffer dst = ByteBuffer.wrap(b, off, len);
int remaining = dst.remaining();
if (remaining == 0) {
return 0;
}
long written =
content.writeTo(
new AnonWritableByteChannel() {
@Override
public long write(ByteBuffer[] srcs, int offset, int length) {
// srcs here is the bytes of content
long total = 0;
for (int i = offset; i < length; i++) {
ByteBuffer src = srcs[i];
// copy what we can from our src to the dst buffer
long written = Buffers.copy(src, dst);
total += written;
}
return total;
}
});
// if the dst has space, but we didn't write anything means we didn't have anything to write
if (written == 0) {
return -1;
}
return Math.toIntExact(written);
}
private abstract static class AnonWritableByteChannel implements UnbufferedWritableByteChannel {
@Override
public boolean isOpen() {
return true;
}
@Override
public void close() {}
}
}