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
92
93
94
95
96
97
98
99
|
package backoff
import (
"context"
"sync"
"time"
)
type controller struct {
ctx context.Context
cancel func()
ig IntervalGenerator
maxRetries int64
mu *sync.RWMutex
next chan struct{} // user-facing channel
resetTimer chan time.Duration
retries int64
timer *time.Timer
}
func newController(ctx context.Context, ig IntervalGenerator, options ...ControllerOption) *controller {
cctx, cancel := context.WithCancel(ctx) // DO NOT fire this cancel here
maxRetries := int64(10)
for _, option := range options {
switch option.Ident() {
case identMaxRetries{}:
maxRetries = option.Value().(int64)
}
}
c := &controller{
cancel: cancel,
ctx: cctx,
ig: ig,
maxRetries: maxRetries,
mu: &sync.RWMutex{},
next: make(chan struct{}, 1),
resetTimer: make(chan time.Duration, 1),
timer: time.NewTimer(ig.Next()),
}
// enqueue a single fake event so the user gets to retry once
c.next <- struct{}{}
go c.loop()
return c
}
func (c *controller) loop() {
for {
select {
case <-c.ctx.Done():
return
case d := <-c.resetTimer:
if !c.timer.Stop() {
select {
case <-c.timer.C:
default:
}
}
c.timer.Reset(d)
case <-c.timer.C:
select {
case <-c.ctx.Done():
return
case c.next <- struct{}{}:
}
if c.maxRetries > 0 {
c.retries++
}
if !c.check() {
c.cancel()
return
}
c.resetTimer <- c.ig.Next()
}
}
}
func (c *controller) check() bool {
if c.maxRetries > 0 && c.retries >= c.maxRetries {
return false
}
return true
}
func (c *controller) Done() <-chan struct{} {
c.mu.RLock()
defer c.mu.RUnlock()
return c.ctx.Done()
}
func (c *controller) Next() <-chan struct{} {
c.mu.RLock()
defer c.mu.RUnlock()
return c.next
}
|
