-
Notifications
You must be signed in to change notification settings - Fork 566
/
ticker.go
79 lines (68 loc) · 1.56 KB
/
ticker.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
package backoff
import (
"runtime"
"sync"
"time"
)
// Ticker holds a channel that delivers `ticks' of a clock at times reported by a BackOff.
//
// Ticks will continue to arrive when the previous operation is still running,
// so operations that take a while to fail could run in quick succession.
type Ticker struct {
C <-chan time.Time
c chan time.Time
b BackOff
stop chan struct{}
stopOnce sync.Once
}
// NewTicker returns a new Ticker containing a channel that will send the time at times
// specified by the BackOff argument. Ticker is guaranteed to tick at least once.
// The channel is closed when Stop method is called or BackOff stops.
func NewTicker(b BackOff) *Ticker {
c := make(chan time.Time)
t := &Ticker{
C: c,
c: c,
b: b,
stop: make(chan struct{}),
}
go t.run()
runtime.SetFinalizer(t, (*Ticker).Stop)
return t
}
// Stop turns off a ticker. After Stop, no more ticks will be sent.
func (t *Ticker) Stop() {
t.stopOnce.Do(func() { close(t.stop) })
}
func (t *Ticker) run() {
c := t.c
defer close(c)
t.b.Reset()
// Ticker is guaranteed to tick at least once.
afterC := t.send(time.Now())
for {
if afterC == nil {
return
}
select {
case tick := <-afterC:
afterC = t.send(tick)
case <-t.stop:
t.c = nil // Prevent future ticks from being sent to the channel.
return
}
}
}
func (t *Ticker) send(tick time.Time) <-chan time.Time {
select {
case t.c <- tick:
case <-t.stop:
return nil
}
next := t.b.NextBackOff()
if next == Stop {
t.Stop()
return nil
}
return time.After(next)
}