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backoff.go
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backoff.go
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package bboff
import (
"sync"
"time"
"github.com/google/uuid"
)
// BackoffBatch containts information needed for the backoff to work
type BackoffBatch struct {
uuid uuid.UUID
shouldIncrement bool
}
// BackoffIntervals holds data about all the intervals
type BackoffIntervals struct {
StartInterval time.Duration
Multiplier float64
MaxInterval time.Duration
}
// ExponentialBackoff takes care of exp. backoff for a request type
type ExponentialBackoff struct {
intervals BackoffIntervals
// The time that the current backoff lasts to, nil if not in backoff mode
backoffUntil *time.Time
// Current amount of increments on the backoff
increments int
// Lock to handle async calls to the struct
mutex *sync.Mutex
// The batch works as a way to identify which processes calls the Backoff function in an async environment
// When Backoff() is called it will only increment once per batch
batchUUID uuid.UUID
}
// NewExponentialBackoff will initialize and create a new ExponentialBackoff
func NewExponentialBackoff(boInvervals BackoffIntervals) *ExponentialBackoff {
return &ExponentialBackoff{
intervals: boInvervals,
mutex: &sync.Mutex{},
}
}
// CanProceed returns true if it's no longer in backoff, it also returns a batch that's needed for the Backoff() call
func (back *ExponentialBackoff) CanProceed() (bool, BackoffBatch) {
back.mutex.Lock()
canProceed := !back.inBackoff() || back.backoffUntil.Before(time.Now())
backoffBatch := BackoffBatch{
uuid: back.batchUUID,
shouldIncrement: false,
}
if canProceed && back.inBackoff() {
back.resetTimer()
backoffBatch = BackoffBatch{
uuid: uuid.New(),
shouldIncrement: true,
}
// Set the new batch ID, only one will have the `shouldIncrement` set to true
back.batchUUID = backoffBatch.uuid
}
back.mutex.Unlock()
return canProceed, backoffBatch
}
// Backoff will wither start a new backoff or increment the backoff time, based on the batch
func (back *ExponentialBackoff) Backoff(batch BackoffBatch) {
back.mutex.Lock()
// If it's in backoff and it shouldn't increment
if back.inBackoff() && !batch.shouldIncrement {
back.mutex.Unlock()
return
}
back.startOrIncrementBackoff(batch)
back.mutex.Unlock()
}
func (back *ExponentialBackoff) startOrIncrementBackoff(batch BackoffBatch) {
if batch.shouldIncrement {
incrementsMultiplier := back.increments
if incrementsMultiplier == 0 {
incrementsMultiplier = 1
}
backOffInterval := float64(back.intervals.StartInterval) * back.intervals.Multiplier * float64(incrementsMultiplier)
if backOffInterval > float64(back.intervals.MaxInterval) {
backOffInterval = float64(back.intervals.MaxInterval)
}
backoffDuration := time.Duration(backOffInterval)
backoffTime := time.Now().Add(backoffDuration)
back.backoffUntil = &backoffTime
back.increments++
} else {
backoffTime := time.Now().Add(back.intervals.StartInterval)
back.backoffUntil = &backoffTime
back.increments = 0
}
}
func (back *ExponentialBackoff) inBackoff() bool {
return back.backoffUntil != nil
}
func (back *ExponentialBackoff) resetTimer() {
back.backoffUntil = nil
}