-
Notifications
You must be signed in to change notification settings - Fork 1
/
wait.go
332 lines (294 loc) · 9.98 KB
/
wait.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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
/*
Copyright 2014 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package wait
import (
"errors"
"math/rand"
"time"
"k8s.io/client-go/pkg/util/runtime"
)
// For any test of the style:
// ...
// <- time.After(timeout):
// t.Errorf("Timed out")
// The value for timeout should effectively be "forever." Obviously we don't want our tests to truly lock up forever, but 30s
// is long enough that it is effectively forever for the things that can slow down a run on a heavily contended machine
// (GC, seeks, etc), but not so long as to make a developer ctrl-c a test run if they do happen to break that test.
var ForeverTestTimeout = time.Second * 30
// NeverStop may be passed to Until to make it never stop.
var NeverStop <-chan struct{} = make(chan struct{})
// Forever calls f every period for ever.
//
// Forever is syntactic sugar on top of Until.
func Forever(f func(), period time.Duration) {
Until(f, period, NeverStop)
}
// Until loops until stop channel is closed, running f every period.
//
// Until is syntactic sugar on top of JitterUntil with zero jitter factor and
// with sliding = true (which means the timer for period starts after the f
// completes).
func Until(f func(), period time.Duration, stopCh <-chan struct{}) {
JitterUntil(f, period, 0.0, true, stopCh)
}
// NonSlidingUntil loops until stop channel is closed, running f every
// period.
//
// NonSlidingUntil is syntactic sugar on top of JitterUntil with zero jitter
// factor, with sliding = false (meaning the timer for period starts at the same
// time as the function starts).
func NonSlidingUntil(f func(), period time.Duration, stopCh <-chan struct{}) {
JitterUntil(f, period, 0.0, false, stopCh)
}
// JitterUntil loops until stop channel is closed, running f every period.
//
// If jitterFactor is positive, the period is jittered before every run of f.
// If jitterFactor is not positive, the period is unchanged and not jitterd.
//
// If slidingis true, the period is computed after f runs. If it is false then
// period includes the runtime for f.
//
// Close stopCh to stop. f may not be invoked if stop channel is already
// closed. Pass NeverStop to if you don't want it stop.
func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding bool, stopCh <-chan struct{}) {
for {
select {
case <-stopCh:
return
default:
}
jitteredPeriod := period
if jitterFactor > 0.0 {
jitteredPeriod = Jitter(period, jitterFactor)
}
var t *time.Timer
if !sliding {
t = time.NewTimer(jitteredPeriod)
}
func() {
defer runtime.HandleCrash()
f()
}()
if sliding {
t = time.NewTimer(jitteredPeriod)
}
// NOTE: b/c there is no priority selection in golang
// it is possible for this to race, meaning we could
// trigger t.C and stopCh, and t.C select falls through.
// In order to mitigate we re-check stopCh at the beginning
// of every loop to prevent extra executions of f().
select {
case <-stopCh:
return
case <-t.C:
}
}
}
// Jitter returns a time.Duration between duration and duration + maxFactor *
// duration.
//
// This allows clients to avoid converging on periodic behavior. If maxFactor
// is 0.0, a suggested default value will be chosen.
func Jitter(duration time.Duration, maxFactor float64) time.Duration {
if maxFactor <= 0.0 {
maxFactor = 1.0
}
wait := duration + time.Duration(rand.Float64()*maxFactor*float64(duration))
return wait
}
// ErrWaitTimeout is returned when the condition exited without success.
var ErrWaitTimeout = errors.New("timed out waiting for the condition")
// ConditionFunc returns true if the condition is satisfied, or an error
// if the loop should be aborted.
type ConditionFunc func() (done bool, err error)
// Backoff holds parameters applied to a Backoff function.
type Backoff struct {
Duration time.Duration // the base duration
Factor float64 // Duration is multipled by factor each iteration
Jitter float64 // The amount of jitter applied each iteration
Steps int // Exit with error after this many steps
}
// ExponentialBackoff repeats a condition check with exponential backoff.
//
// It checks the condition up to Steps times, increasing the wait by multipling
// the previous duration by Factor.
//
// If Jitter is greater than zero, a random amount of each duration is added
// (between duration and duration*(1+jitter)).
//
// If the condition never returns true, ErrWaitTimeout is returned. All other
// errors terminate immediately.
func ExponentialBackoff(backoff Backoff, condition ConditionFunc) error {
duration := backoff.Duration
for i := 0; i < backoff.Steps; i++ {
if i != 0 {
adjusted := duration
if backoff.Jitter > 0.0 {
adjusted = Jitter(duration, backoff.Jitter)
}
time.Sleep(adjusted)
duration = time.Duration(float64(duration) * backoff.Factor)
}
if ok, err := condition(); err != nil || ok {
return err
}
}
return ErrWaitTimeout
}
// Poll tries a condition func until it returns true, an error, or the timeout
// is reached.
//
// Poll always waits the interval before the run of 'condition'.
// 'condition' will always be invoked at least once.
//
// Some intervals may be missed if the condition takes too long or the time
// window is too short.
//
// If you want to Poll something forever, see PollInfinite.
func Poll(interval, timeout time.Duration, condition ConditionFunc) error {
return pollInternal(poller(interval, timeout), condition)
}
func pollInternal(wait WaitFunc, condition ConditionFunc) error {
return WaitFor(wait, condition, NeverStop)
}
// PollImmediate tries a condition func until it returns true, an error, or the timeout
// is reached.
//
// Poll always checks 'condition' before waiting for the interval. 'condition'
// will always be invoked at least once.
//
// Some intervals may be missed if the condition takes too long or the time
// window is too short.
//
// If you want to Poll something forever, see PollInfinite.
func PollImmediate(interval, timeout time.Duration, condition ConditionFunc) error {
return pollImmediateInternal(poller(interval, timeout), condition)
}
func pollImmediateInternal(wait WaitFunc, condition ConditionFunc) error {
done, err := condition()
if err != nil {
return err
}
if done {
return nil
}
return pollInternal(wait, condition)
}
// PollInfinite tries a condition func until it returns true or an error
//
// PollInfinite always waits the interval before the run of 'condition'.
//
// Some intervals may be missed if the condition takes too long or the time
// window is too short.
func PollInfinite(interval time.Duration, condition ConditionFunc) error {
done := make(chan struct{})
defer close(done)
return PollUntil(interval, condition, done)
}
// PollImmediateInfinite tries a condition func until it returns true or an error
//
// PollImmediateInfinite runs the 'condition' before waiting for the interval.
//
// Some intervals may be missed if the condition takes too long or the time
// window is too short.
func PollImmediateInfinite(interval time.Duration, condition ConditionFunc) error {
done, err := condition()
if err != nil {
return err
}
if done {
return nil
}
return PollInfinite(interval, condition)
}
// PollUntil tries a condition func until it returns true, an error or stopCh is
// closed.
//
// PolUntil always waits interval before the first run of 'condition'.
// 'condition' will always be invoked at least once.
func PollUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) error {
return WaitFor(poller(interval, 0), condition, stopCh)
}
// WaitFunc creates a channel that receives an item every time a test
// should be executed and is closed when the last test should be invoked.
type WaitFunc func(done <-chan struct{}) <-chan struct{}
// WaitFor continually checks 'fn' as driven by 'wait'.
//
// WaitFor gets a channel from 'wait()'', and then invokes 'fn' once for every value
// placed on the channel and once more when the channel is closed.
//
// If 'fn' returns an error the loop ends and that error is returned, and if
// 'fn' returns true the loop ends and nil is returned.
//
// ErrWaitTimeout will be returned if the channel is closed without fn ever
// returning true.
func WaitFor(wait WaitFunc, fn ConditionFunc, done <-chan struct{}) error {
c := wait(done)
for {
_, open := <-c
ok, err := fn()
if err != nil {
return err
}
if ok {
return nil
}
if !open {
break
}
}
return ErrWaitTimeout
}
// poller returns a WaitFunc that will send to the channel every interval until
// timeout has elapsed and then closes the channel.
//
// Over very short intervals you may receive no ticks before the channel is
// closed. A timeout of 0 is interpreted as an infinity.
//
// Output ticks are not buffered. If the channel is not ready to receive an
// item, the tick is skipped.
func poller(interval, timeout time.Duration) WaitFunc {
return WaitFunc(func(done <-chan struct{}) <-chan struct{} {
ch := make(chan struct{})
go func() {
defer close(ch)
tick := time.NewTicker(interval)
defer tick.Stop()
var after <-chan time.Time
if timeout != 0 {
// time.After is more convenient, but it
// potentially leaves timers around much longer
// than necessary if we exit early.
timer := time.NewTimer(timeout)
after = timer.C
defer timer.Stop()
}
for {
select {
case <-tick.C:
// If the consumer isn't ready for this signal drop it and
// check the other channels.
select {
case ch <- struct{}{}:
default:
}
case <-after:
return
case <-done:
return
}
}
}()
return ch
})
}