-
Notifications
You must be signed in to change notification settings - Fork 2.9k
/
backoff.go
134 lines (106 loc) · 3.39 KB
/
backoff.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
// Copyright 2018-2019 Authors of Cilium
//
// 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 backoff
import (
"context"
"fmt"
"math"
"math/rand"
"time"
"github.com/cilium/cilium/pkg/logging"
"github.com/cilium/cilium/pkg/logging/logfields"
"github.com/cilium/cilium/pkg/uuid"
"github.com/sirupsen/logrus"
)
var log = logging.DefaultLogger.WithField(logfields.LogSubsys, "backoff")
// NodeManager is the interface required to implement cluster size dependent
// intervals
type NodeManager interface {
ClusterSizeDependantInterval(baseInterval time.Duration) time.Duration
}
// Exponential implements an exponential backoff
type Exponential struct {
// Min is the minimal backoff time, if unspecified, 1 second will be
// used
Min time.Duration
// Max is the maximum backoff time, if unspecified, no maximum time is
// applied
Max time.Duration
// Factor is the factor the backoff time grows exponentially, if
// unspecified, a factor of 2.0 will be used
Factor float64
// Jitter, when enabled, adds random jitter to the interval
Jitter bool
// NodeManager enables the use of cluster size dependent backoff
// intervals, i.e. the larger the cluster, the longer the backoff
// interval
NodeManager NodeManager
// Name is a free form string describing the operation subject to the
// backoff, if unspecified, a UUID is generated. This string is used
// for logging purposes.
Name string
attempt int
}
// CalculateDuration calculates the backoff duration based on minimum base
// interval, exponential factor, jitter and number of failures.
func CalculateDuration(min, max time.Duration, factor float64, jitter bool, failures int) time.Duration {
minFloat := float64(min)
maxFloat := float64(max)
t := minFloat * math.Pow(factor, float64(failures))
if max != time.Duration(0) && t > maxFloat {
t = maxFloat
}
if jitter {
t = rand.Float64()*(t-minFloat) + minFloat
}
return time.Duration(t)
}
// Wait waits for the required time using an exponential backoff
func (b *Exponential) Wait(ctx context.Context) error {
b.attempt++
t := b.Duration(b.attempt)
log.WithFields(logrus.Fields{
"time": t,
"attempt": b.attempt,
"name": b.Name,
}).Debug("Sleeping with exponential backoff")
select {
case <-ctx.Done():
return fmt.Errorf("exponential backoff cancelled via context: %s", ctx.Err())
case <-time.After(t):
}
return nil
}
// Duration returns the wait duration for the nth attempt
func (b *Exponential) Duration(attempt int) time.Duration {
if b.Name == "" {
b.Name = uuid.NewUUID().String()
}
min := time.Duration(1) * time.Second
if b.Min != time.Duration(0) {
min = b.Min
}
factor := float64(2)
if b.Factor != float64(0) {
factor = b.Factor
}
t := CalculateDuration(min, b.Max, factor, b.Jitter, attempt)
if b.NodeManager != nil {
t = b.NodeManager.ClusterSizeDependantInterval(t)
}
if b.Max != time.Duration(0) && t > b.Max {
t = b.Max
}
return t
}