frp/pkg/util/wait/backoff.go

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// Copyright 2023 The frp 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 (
"math/rand"
"time"
"github.com/fatedier/frp/pkg/util/util"
)
type BackoffFunc func(previousDuration time.Duration, previousConditionError bool) time.Duration
func (f BackoffFunc) Backoff(previousDuration time.Duration, previousConditionError bool) time.Duration {
return f(previousDuration, previousConditionError)
}
type BackoffManager interface {
Backoff(previousDuration time.Duration, previousConditionError bool) time.Duration
}
type FastBackoffOptions struct {
Duration time.Duration
Factor float64
Jitter float64
MaxDuration time.Duration
InitDurationIfFail time.Duration
// If FastRetryCount > 0, then within the FastRetryWindow time window,
// the retry will be performed with a delay of FastRetryDelay for the first FastRetryCount calls.
FastRetryCount int
FastRetryDelay time.Duration
FastRetryJitter float64
FastRetryWindow time.Duration
}
type fastBackoffImpl struct {
options FastBackoffOptions
lastCalledTime time.Time
consecutiveErrCount int
fastRetryCutoffTime time.Time
countsInFastRetryWindow int
}
func NewFastBackoffManager(options FastBackoffOptions) BackoffManager {
return &fastBackoffImpl{
options: options,
countsInFastRetryWindow: 1,
}
}
func (f *fastBackoffImpl) Backoff(previousDuration time.Duration, previousConditionError bool) time.Duration {
if f.lastCalledTime.IsZero() {
f.lastCalledTime = time.Now()
return f.options.Duration
}
now := time.Now()
f.lastCalledTime = now
if previousConditionError {
f.consecutiveErrCount++
} else {
f.consecutiveErrCount = 0
}
if f.options.FastRetryCount > 0 && previousConditionError {
f.countsInFastRetryWindow++
if f.countsInFastRetryWindow <= f.options.FastRetryCount {
return Jitter(f.options.FastRetryDelay, f.options.FastRetryJitter)
}
if now.After(f.fastRetryCutoffTime) {
// reset
f.fastRetryCutoffTime = now.Add(f.options.FastRetryWindow)
f.countsInFastRetryWindow = 0
}
}
if previousConditionError {
var duration time.Duration
if f.consecutiveErrCount == 1 {
duration = util.EmptyOr(f.options.InitDurationIfFail, previousDuration)
} else {
duration = previousDuration
}
duration = util.EmptyOr(duration, time.Second)
if f.options.Factor != 0 {
duration = time.Duration(float64(duration) * f.options.Factor)
}
if f.options.Jitter > 0 {
duration = Jitter(duration, f.options.Jitter)
}
if f.options.MaxDuration > 0 && duration > f.options.MaxDuration {
duration = f.options.MaxDuration
}
return duration
}
return f.options.Duration
}
func BackoffUntil(f func() (bool, error), backoff BackoffManager, sliding bool, stopCh <-chan struct{}) {
var delay time.Duration
previousError := false
ticker := time.NewTicker(backoff.Backoff(delay, previousError))
defer ticker.Stop()
for {
select {
case <-stopCh:
return
default:
}
if !sliding {
delay = backoff.Backoff(delay, previousError)
}
if done, err := f(); done {
return
} else if err != nil {
previousError = true
} else {
previousError = false
}
if sliding {
delay = backoff.Backoff(delay, previousError)
}
ticker.Reset(delay)
select {
case <-stopCh:
return
case <-ticker.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
}
func Until(f func(), period time.Duration, stopCh <-chan struct{}) {
ff := func() (bool, error) {
f()
return false, nil
}
BackoffUntil(ff, BackoffFunc(func(time.Duration, bool) time.Duration {
return period
}), true, stopCh)
}