1/*
2Copyright 2017 The Kubernetes Authors.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8    http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17package ipam
18
19import (
20	"time"
21)
22
23// Timeout manages the resync loop timing for a given node sync operation. The
24// timeout changes depending on whether or not there was an error reported for
25// the operation. Consecutive errors will result in exponential backoff to a
26// maxBackoff timeout.
27type Timeout struct {
28	// Resync is the default timeout duration when there are no errors.
29	Resync time.Duration
30	// MaxBackoff is the maximum timeout when in a error backoff state.
31	MaxBackoff time.Duration
32	// InitialRetry is the initial retry interval when an error is reported.
33	InitialRetry time.Duration
34
35	// errs is the count of consecutive errors that have occurred.
36	errs int
37	// current is the current backoff timeout.
38	current time.Duration
39}
40
41// Update the timeout with the current error state.
42func (b *Timeout) Update(ok bool) {
43	if ok {
44		b.errs = 0
45		b.current = b.Resync
46		return
47	}
48
49	b.errs++
50	if b.errs == 1 {
51		b.current = b.InitialRetry
52		return
53	}
54
55	b.current *= 2
56	if b.current >= b.MaxBackoff {
57		b.current = b.MaxBackoff
58	}
59}
60
61// Next returns the next operation timeout given the disposition of err.
62func (b *Timeout) Next() time.Duration {
63	if b.errs == 0 {
64		return b.Resync
65	}
66	return b.current
67}
68