khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame] | 1 | /* |
Joey Armstrong | f850dca | 2024-01-18 18:25:46 -0500 | [diff] [blame] | 2 | * Copyright 2021-2024 Open Networking Foundation (ONF) and the ONF Contributors |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame] | 3 | |
Mahir Gunyel | 7e4cd8a | 2023-07-24 09:44:07 +0300 | [diff] [blame] | 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame] | 7 | |
Mahir Gunyel | 7e4cd8a | 2023-07-24 09:44:07 +0300 | [diff] [blame] | 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame] | 9 | |
Mahir Gunyel | 7e4cd8a | 2023-07-24 09:44:07 +0300 | [diff] [blame] | 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame] | 15 | */ |
| 16 | package grpc |
| 17 | |
| 18 | import ( |
| 19 | "context" |
| 20 | "errors" |
| 21 | "fmt" |
| 22 | "math" |
| 23 | "os" |
| 24 | "reflect" |
| 25 | "sync" |
| 26 | "time" |
| 27 | ) |
| 28 | |
| 29 | const ( |
| 30 | incrementalFactor = 1.5 |
| 31 | minBackOff = 10 * time.Millisecond |
| 32 | ) |
| 33 | |
| 34 | type Backoff struct { |
| 35 | attempt int |
| 36 | initialInterval time.Duration |
| 37 | maxElapsedTime time.Duration |
| 38 | maxInterval time.Duration |
| 39 | totalElapsedTime time.Duration |
| 40 | mutex sync.RWMutex |
| 41 | } |
| 42 | |
| 43 | func NewBackoff(initialInterval, maxInterval, maxElapsedTime time.Duration) *Backoff { |
| 44 | bo := &Backoff{} |
| 45 | bo.initialInterval = initialInterval |
| 46 | bo.maxInterval = maxInterval |
| 47 | bo.maxElapsedTime = maxElapsedTime |
| 48 | return bo |
| 49 | } |
| 50 | |
| 51 | func (bo *Backoff) Backoff(ctx context.Context) error { |
| 52 | duration, err := bo.getBackOffDuration() |
| 53 | if err != nil { |
| 54 | return err |
| 55 | } |
| 56 | |
| 57 | ticker := time.NewTicker(duration) |
| 58 | defer ticker.Stop() |
| 59 | select { |
| 60 | case <-ctx.Done(): |
| 61 | return ctx.Err() |
| 62 | case <-ticker.C: |
| 63 | } |
| 64 | return nil |
| 65 | } |
| 66 | |
| 67 | func (bo *Backoff) getBackOffDuration() (duration time.Duration, err error) { |
| 68 | err = nil |
| 69 | defer func() { |
| 70 | bo.mutex.Lock() |
| 71 | defer bo.mutex.Unlock() |
| 72 | bo.attempt += 1 |
| 73 | bo.totalElapsedTime += duration |
| 74 | if bo.maxElapsedTime > 0 && bo.totalElapsedTime > bo.maxElapsedTime { |
| 75 | err = errors.New("max elapsed backoff time reached") |
| 76 | } |
| 77 | }() |
| 78 | |
| 79 | if bo.initialInterval <= minBackOff { |
| 80 | bo.initialInterval = minBackOff |
| 81 | } |
| 82 | if bo.initialInterval > bo.maxInterval { |
| 83 | duration = bo.initialInterval |
| 84 | return |
| 85 | } |
| 86 | |
| 87 | // Calculate incremental duration |
| 88 | minf := float64(bo.initialInterval) |
| 89 | durf := minf * math.Pow(incrementalFactor, float64(bo.attempt)) |
| 90 | |
| 91 | if durf > math.MaxInt64 { |
| 92 | duration = bo.maxInterval |
| 93 | return |
| 94 | } |
| 95 | duration = time.Duration(durf) |
| 96 | |
| 97 | //Keep within bounds |
| 98 | if duration < bo.initialInterval { |
| 99 | duration = bo.initialInterval |
| 100 | } |
| 101 | if duration > bo.maxInterval { |
| 102 | duration = bo.maxInterval |
| 103 | } |
| 104 | return |
| 105 | } |
| 106 | |
| 107 | func (bo *Backoff) Reset() { |
| 108 | bo.mutex.Lock() |
| 109 | defer bo.mutex.Unlock() |
| 110 | bo.attempt = 0 |
| 111 | bo.totalElapsedTime = 0 |
| 112 | } |
| 113 | |
| 114 | func SetFromEnvVariable(key string, variableToSet interface{}) error { |
| 115 | if _, ok := variableToSet.(*time.Duration); !ok { |
| 116 | return fmt.Errorf("unsupported type %T", variableToSet) |
| 117 | } |
| 118 | if valStr, present := os.LookupEnv(key); present { |
| 119 | val, err := time.ParseDuration(valStr) |
| 120 | if err != nil { |
| 121 | return err |
| 122 | } |
| 123 | reflect.ValueOf(variableToSet).Elem().Set(reflect.ValueOf(val)) |
| 124 | } |
| 125 | return nil |
| 126 | } |