-
Notifications
You must be signed in to change notification settings - Fork 74
/
gcs_read_seek_closer.go
69 lines (61 loc) · 1.3 KB
/
gcs_read_seek_closer.go
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
package utils
import (
"context"
"fmt"
"io"
"cloud.google.com/go/storage"
)
type GCSReadSeekCloser struct {
size int64
object *storage.ObjectHandle
ctx context.Context
offset int64
r io.ReadCloser
}
func (r *GCSReadSeekCloser) Read(p []byte) (int, error) {
n, err := r.r.Read(p)
r.offset += int64(n)
return n, err
}
func (r *GCSReadSeekCloser) Seek(offset int64, whence int) (int64, error) {
var seekTo int64
switch whence {
case io.SeekCurrent:
seekTo = r.offset + offset
case io.SeekEnd:
seekTo = r.size + offset
case io.SeekStart:
seekTo = offset
default:
return 0, fmt.Errorf("unrecognized whence: %d", whence)
}
// only request a new range if we're not currently at the target position
if seekTo != r.offset {
err := r.r.Close()
if err != nil {
return 0, err
}
reader, err := r.object.NewRangeReader(r.ctx, seekTo, -1)
if err != nil {
return 0, err
}
r.r = reader
r.offset = seekTo
}
return seekTo, nil
}
func (r *GCSReadSeekCloser) Close() error {
return r.r.Close()
}
func NewGCSReadSeekCloser(ctx context.Context, object *storage.ObjectHandle) (*GCSReadSeekCloser, error) {
r, err := object.NewReader(ctx)
if err != nil {
return nil, err
}
return &GCSReadSeekCloser{
size: r.Attrs.Size,
object: object,
r: r,
ctx: ctx,
}, nil
}