jpillora

Simple backoff algorithm in Go (golang)

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Backoff

Name: backoff
Brand: backoff
SKU: //jpillora/backoff
Rating: 2.875 (450 reviews)

A simple exponential backoff counter in Go (Golang)

Install

$ go get -v github.com/jpillora/backoff

Usage

Backoff is a

time.Duration

counter. It starts at

Min

. After every call to

Duration()

it is multiplied by

Factor

. It is capped at

Max

. It returns to

Min

on every call to

Reset()

Jitter

adds randomness (see below). Used in conjunction with the

time

package.

Simple example

b := &backoff.Backoff{
    //These are the defaults
    Min:    100 * time.Millisecond,
    Max:    10 * time.Second,
    Factor: 2,
    Jitter: false,
}

fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("Reset!\n")
b.Reset()
fmt.Printf("%s\n", b.Duration())

100ms
200ms
400ms
Reset!
100ms

Example using

net

package

b := &backoff.Backoff{
    Max:    5 * time.Minute,
}

for {
    conn, err := net.Dial("tcp", "example.com:5309")
    if err != nil {
        d := b.Duration()
        fmt.Printf("%s, reconnecting in %s", err, d)
        time.Sleep(d)
        continue
    }
    //connected
    b.Reset()
    conn.Write([]byte("hello world!"))
    // ... Read ... Write ... etc
    conn.Close()
    //disconnected
}

Example using

Jitter

Enabling

Jitter

adds some randomization to the backoff durations. See Amazon's writeup of performance gains using jitter. Seeding is not necessary but doing so gives repeatable results.

import "math/rand"

b := &backoff.Backoff{
    Jitter: true,
}
rand.Seed(42)
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("Reset!\n")
b.Reset()
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())

100ms
106.600049ms
281.228155ms
Reset!
100ms
104.381845ms
214.957989ms

Documentation

https://godoc.org/github.com/jpillora/backoff

Credits

Forked from some JavaScript written by @tj

backoff

by jpillora