README
¶
goback
Goback implements a simple exponential backoff.
An exponential backoff approach is typically used when treating with potentially faulty/slow systems. If a system fails quick retries may exacerbate the system specially when the system is dealing with several clients. In this case a backoff provides the faulty system enough room to recover.
How to use
func main() {
b := &goback.SimpleBackoff(
Min: 100 * time.Millisecond,
Max: 60 * time.Second,
Factor: 2,
)
goback.Wait(b) // sleeps 100ms
goback.Wait(b) // sleeps 200ms
goback.Wait(b) // sleeps 400ms
fmt.Println(b.NextRun()) // prints 800ms
b.Reset() // resets the backoff
goback.Wait(b) // sleeps 100ms
}
Furter examples can be found in the examples folder.
Strategies
At the moment there are two backoff strategies implemented.
Simple Backoff
It starts with a minumum duration and multiplies it by the factor until the maximum waiting time is reached. In that case it will return Max.
The optional MaxAttempts will limit the maximum number of retries and will return an error when is exceeded.
Jitter Backoff
The Jitter strategy is based on the simple backoff but adds a light randomisation to minimise collisions between contending clients.
The result of the 'NextDuration()' method will be a random duration between [d-min, d+min] where d is the expected duration without jitter and min is the minimum duration.
Extensibility
By creating structs that implement the methods of the Backoff interface you will be able to use them as a backoff strategy.
A naive example of this is:
type NaiveBackoff struct{}
func (b *NaiveBackoff) NextAttempt() (time.Duration, error) { return time.Second, nil }
func (b *NaiveBackoff) Reset() { }
This will return always a 1s duration.
Credits
This package is inspired in https://github.com/jpillora/backoff
License
Distributed under MIT license. See LICENSE file for more information.
Documentation
¶
Overview ¶
Package goback implements a simple exponential backoff
An exponential backoff approach is typically used when treating with potentially faulty/slow systems. If a system fails quick retries may exacerbate the system specially when the system is dealing with several clients. In this case a backoff provides the faulty system enough room to recover.
Simple example:
func main() {
b := &goback.SimpleBackoff(
Min: 100 * time.Millisecond,
Max: 60 * time.Second,
Factor: 2,
)
goback.Wait(b) // sleeps 100ms
goback.Wait(b) // sleeps 200ms
goback.Wait(b) // sleeps 400ms
fmt.Println(b.NextRun()) // prints 800ms
b.Reset() // resets the backoff
goback.Wait(b) // sleeps 100ms
}
Furter examples can be found in the examples folder in the repository.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( // ErrMaxAttemptsExceeded indicates that the maximum retries has been // excedeed. Usually to consider a service unreachable/unavailable. ErrMaxAttemptsExceeded = errors.New("maximum of attempts exceeded") )
Functions ¶
func After ¶
After returns a channel that will be called after the time specified by the backoff strategy or will exit immediately with an error.
func GetNextDuration ¶
GetNextDuration returns the duration for the strategies considering the minimum and maximum durations, the factor of increase and the number of attemtps tried.
Types ¶
type Backoff ¶
type Backoff interface {
// NextAttempt returns the duration to wait for the next retry.
NextAttempt() (time.Duration, error)
// Reset clears the number of tries. Next call to NextAttempt will return
// the minimum backoff time (if there is no error).
Reset()
}
Backoff is the interface that any Backoff strategy needs to implement.
type JitterBackoff ¶
type JitterBackoff SimpleBackoff
JitterBackoff provides an strategy similar to SimpleBackoff but lightly randomises the duration to minimise collisions between contending clients.
func (*JitterBackoff) NextAttempt ¶
func (b *JitterBackoff) NextAttempt() (time.Duration, error)
NextAttempt returns the duration to wait for the next retry.
type SimpleBackoff ¶
type SimpleBackoff struct {
Attempts int
MaxAttempts int
Factor float64
Min time.Duration
Max time.Duration
}
SimpleBackoff provides a simple strategy to backoff.
func (*SimpleBackoff) NextAttempt ¶
func (b *SimpleBackoff) NextAttempt() (time.Duration, error)
NextAttempt returns the duration to wait for the next retry.
func (*SimpleBackoff) Reset ¶
func (b *SimpleBackoff) Reset()
Reset clears the number of tries. Next call to NextAttempt will return the minimum backoff time (if there is no error).
Source Files
Directories