forked from canonical/lxd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
canceler.go
78 lines (64 loc) · 1.48 KB
/
canceler.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
package cancel
import (
"fmt"
"net/http"
"sync"
)
// Canceler tracks a cancelable operation
type Canceler struct {
reqChCancel map[*http.Request]chan struct{}
lock sync.Mutex
}
// NewCanceler returns a new Canceler struct
func NewCanceler() *Canceler {
c := Canceler{}
c.lock.Lock()
c.reqChCancel = make(map[*http.Request]chan struct{})
c.lock.Unlock()
return &c
}
// Cancelable indicates whether there are operations that support cancelation
func (c *Canceler) Cancelable() bool {
c.lock.Lock()
length := len(c.reqChCancel)
c.lock.Unlock()
return length > 0
}
// Cancel will attempt to cancel all ongoing operations
func (c *Canceler) Cancel() error {
if !c.Cancelable() {
return fmt.Errorf("This operation can't be canceled at this time")
}
c.lock.Lock()
for req, ch := range c.reqChCancel {
close(ch)
delete(c.reqChCancel, req)
}
c.lock.Unlock()
return nil
}
// CancelableDownload performs an http request and allows for it to be canceled at any time
func CancelableDownload(c *Canceler, client *http.Client, req *http.Request) (*http.Response, chan bool, error) {
chDone := make(chan bool)
chCancel := make(chan struct{})
if c != nil {
c.lock.Lock()
c.reqChCancel[req] = chCancel
c.lock.Unlock()
}
req.Cancel = chCancel
go func() {
<-chDone
if c != nil {
c.lock.Lock()
delete(c.reqChCancel, req)
c.lock.Unlock()
}
}()
resp, err := client.Do(req)
if err != nil {
close(chDone)
return nil, nil, err
}
return resp, chDone, nil
}