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.

Install goback by executing the command below:

$ go get -v github.com/dnaeon/goback

Here is an example which uses the SimpleBackoff stategy:

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.NextAttempt()) // prints 800ms
        b.Reset()                    // resets the backoff
        goback.Wait(b)               // sleeps 100ms
}

More examples can be found in the examples folder.

At the moment there are two backoff strategies implemented.

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.

The Jitter strategy is based on the simple backoff but adds a light randomisation to minimise collisions between contending clients.

The result of the 'NextAttempt()' 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.

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.

This package is a fork of https://github.com/carlescere/goback

Distributed under MIT license. See LICENSE file for more information.