mirror of
https://github.com/google/alertmanager-irc-relay.git
synced 2024-12-02 16:09:25 +01:00
103 lines
2.3 KiB
Go
103 lines
2.3 KiB
Go
// Copyright 2018 Google LLC
|
|
//
|
|
// 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
|
|
//
|
|
// https://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 main
|
|
|
|
import (
|
|
"log"
|
|
"math"
|
|
"math/rand"
|
|
"time"
|
|
)
|
|
|
|
type JitterFunc func(int) int
|
|
|
|
type TimeFunc func() time.Time
|
|
|
|
type Delayer interface {
|
|
Delay()
|
|
}
|
|
|
|
type Backoff struct {
|
|
step float64
|
|
maxBackoff float64
|
|
resetDelta float64
|
|
lastAttempt time.Time
|
|
durationUnit time.Duration
|
|
jitterer JitterFunc
|
|
timeGetter TimeFunc
|
|
}
|
|
|
|
func jitterFunc(input int) int {
|
|
if input == 0 {
|
|
return 0
|
|
}
|
|
return rand.Intn(input)
|
|
}
|
|
|
|
func NewBackoff(maxBackoff float64, resetDelta float64,
|
|
durationUnit time.Duration) *Backoff {
|
|
return NewBackoffForTesting(
|
|
maxBackoff, resetDelta, durationUnit, jitterFunc, time.Now)
|
|
}
|
|
|
|
func NewBackoffForTesting(maxBackoff float64, resetDelta float64,
|
|
durationUnit time.Duration, jitterer JitterFunc, timeGetter TimeFunc) *Backoff {
|
|
return &Backoff{
|
|
step: 0,
|
|
maxBackoff: maxBackoff,
|
|
resetDelta: resetDelta,
|
|
lastAttempt: timeGetter(),
|
|
durationUnit: durationUnit,
|
|
jitterer: jitterer,
|
|
timeGetter: timeGetter,
|
|
}
|
|
}
|
|
|
|
func (b *Backoff) maybeReset() {
|
|
now := b.timeGetter()
|
|
lastAttemptDelta := float64(now.Sub(b.lastAttempt) / b.durationUnit)
|
|
b.lastAttempt = now
|
|
|
|
if lastAttemptDelta >= b.resetDelta {
|
|
b.step = 0
|
|
}
|
|
}
|
|
|
|
func (b *Backoff) GetDelay() time.Duration {
|
|
b.maybeReset()
|
|
|
|
var synchronizedDuration float64
|
|
// Do not add any delay the first time.
|
|
if b.step == 0 {
|
|
synchronizedDuration = 0
|
|
} else {
|
|
synchronizedDuration = math.Pow(2, b.step)
|
|
}
|
|
|
|
if synchronizedDuration < b.maxBackoff {
|
|
b.step++
|
|
} else {
|
|
synchronizedDuration = b.maxBackoff
|
|
}
|
|
duration := time.Duration(b.jitterer(int(synchronizedDuration)))
|
|
return duration * b.durationUnit
|
|
}
|
|
|
|
func (b *Backoff) Delay() {
|
|
delay := b.GetDelay()
|
|
log.Printf("Backoff for %s", delay)
|
|
time.Sleep(delay)
|
|
}
|