Jitter Before Starting

 1// run starts the cache watcher loop
 2// it creates a new watcher if there's a problem.
 3func (c *cache) run(service string) {
 4	c.Lock()
 5	c.watchedRunning[service] = true
 6	c.Unlock()
 7	// reset watcher on exit
 8	defer func() {
 9		c.Lock()
10		c.watched = make(map[string]bool)
11		c.watchedRunning[service] = false
12		c.Unlock()
13	}()
14
15	var a, b int
16
17	for {
18		// exit early if already dead
19		if c.quit() {
20			return
21		}
22
23		// jitter before starting
24		j := rand.Int63n(100)
25		time.Sleep(time.Duration(j) * time.Millisecond)
26
27		// create new watcher
28		w, err := c.Registry.Watch(registry.WatchService(service))
29		if err != nil {
30			if c.quit() {
31				return
32			}
33
34			d := backoff(a)
35			c.setStatus(err)
36
37			if a > 3 {
38				a = 0
39			}
40
41			time.Sleep(d)
42			a++
43
44			continue
45		}
46
47		// reset a
48		a = 0
49
50		// watch for events
51		if err := c.watch(w); err != nil {
52			if c.quit() {
53				return
54			}
55
56			d := backoff(b)
57			c.setStatus(err)
58
59			if b > 3 {
60				b = 0
61			}
62
63			time.Sleep(d)
64			b++
65
66			continue
67		}
68
69		// reset b
70		b = 0
71	}
72}