-
Notifications
You must be signed in to change notification settings - Fork 0
/
transfer.go
81 lines (76 loc) · 1.35 KB
/
transfer.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
70
71
72
73
74
75
76
77
78
79
80
81
package grabber
import (
"context"
"io"
"sync/atomic"
)
type transfer struct {
n int64 // must be 64bit aligned on 386
ctx context.Context
lim RateLimiter
w io.Writer
r io.Reader
b []byte
}
func newTransfer(ctx context.Context, lim RateLimiter, dst io.Writer, src io.Reader, buf []byte) *transfer {
return &transfer{
ctx: ctx,
lim: lim,
w: dst,
r: src,
b: buf,
}
}
// copy behaves similarly to io.CopyBuffer except that it checks for cancelation
// of the given context.Context and reports progress in a thread-safe manner.
func (c *transfer) copy() (written int64, err error) {
if c.b == nil {
c.b = make([]byte, 32*1024)
}
for {
select {
case <-c.ctx.Done():
err = c.ctx.Err()
return
default:
// keep working
}
if c.lim != nil {
err = c.lim.WaitN(c.ctx, len(c.b))
if err != nil {
return
}
}
nr, er := c.r.Read(c.b)
if nr > 0 {
nw, ew := c.w.Write(c.b[0:nr])
if nw > 0 {
written += int64(nw)
atomic.StoreInt64(&c.n, written)
}
if ew != nil {
err = ew
break
}
if nr != nw {
err = io.ErrShortWrite
break
}
}
if er != nil {
if er != io.EOF {
err = er
}
break
}
}
return written, err
}
// N returns the number of bytes transferred.
func (c *transfer) N() (n int64) {
if c == nil {
return 0
}
n = atomic.LoadInt64(&c.n)
return
}