retry

README

retry

A simple, stateless, functional mechanism to perform actions repetitively until successful.

Project Status

This project is currently in "pre-release". While the code is heavily tested, the API may change. Vendor (commit or lock) this dependency if you plan on using it.

Install

go get github.com/Rican7/retry

Examples

Basic

Retry(func(attempt uint) error {
	return nil // Do something that may or may not cause an error
})

File Open

const logFilePath = "/var/log/myapp.log"

var logFile *os.File

err := Retry(func(attempt uint) error {
	var err error

	logFile, err = os.Open(logFilePath)

	return err
})

if nil != err {
	log.Fatalf("Unable to open file %q with error %q", logFilePath, err)
}

HTTP request with strategies and backoff

var response *http.Response

action := func(attempt uint) error {
	var err error

	response, err = http.Get("https://api.github.com/repos/Rican7/retry")

	if nil == err && nil != response && response.StatusCode > 200 {
		err = fmt.Errorf("failed to fetch (attempt #%d) with status code: %d", attempt, response.StatusCode)
	}

	return err
}

err := Retry(
	action,
	strategy.Limit(5),
	strategy.Backoff(backoff.Fibonacci(10*time.Millisecond)),
)

if nil != err {
	log.Fatalf("Failed to fetch repository with error %q", err)
}

Retry with backoff jitter

action := func(attempt uint) error {
	return errors.New("something happened")
}

seed := time.Now().UnixNano()
random := rand.New(rand.NewSource(seed))

Retry(
	action,
	strategy.Limit(5),
	strategy.BackoffWithJitter(
		backoff.BinaryExponential(10*time.Millisecond),
		jitter.Deviation(random, 0.5),
	),
)

Documentation

Overview

Package retry provides a simple, stateless, functional mechanism to perform actions repetitively until successful.

Copyright © 2016 Trevor N. Suarez (Rican7)

Example

Retry(func(attempt uint) error {
	return nil // Do something that may or may not cause an error
})

Example (FileOpen)

const logFilePath = "/var/log/myapp.log"

var logFile *os.File

err := Retry(func(attempt uint) error {
	var err error

	logFile, err = os.Open(logFilePath)

	return err
})

if nil != err {
	log.Fatalf("Unable to open file %q with error %q", logFilePath, err)
}

Example (HttpGetWithStrategies)

var response *http.Response

action := func(attempt uint) error {
	var err error

	response, err = http.Get("https://api.github.com/repos/Rican7/retry")

	if nil == err && nil != response && response.StatusCode > 200 {
		err = fmt.Errorf("failed to fetch (attempt #%d) with status code: %d", attempt, response.StatusCode)
	}

	return err
}

err := Retry(
	action,
	strategy.Limit(5),
	strategy.Backoff(backoff.Fibonacci(10*time.Millisecond)),
)

if nil != err {
	log.Fatalf("Failed to fetch repository with error %q", err)
}

Example (WithBackoffJitter)

action := func(attempt uint) error {
	return errors.New("something happened")
}

seed := time.Now().UnixNano()
random := rand.New(rand.NewSource(seed))

Retry(
	action,
	strategy.Limit(5),
	strategy.BackoffWithJitter(
		backoff.BinaryExponential(10*time.Millisecond),
		jitter.Deviation(random, 0.5),
	),
)

Index

• func Retry(action Action, strategies ...strategy.Strategy) error
• type Action

Examples

• Package
• Package (FileOpen)
• Package (HttpGetWithStrategies)
• Package (WithBackoffJitter)

Functions

func Retry

func Retry(action Action, strategies ...strategy.Strategy) error

Retry takes an action and performs it, repetitively, until successful.

Optionally, strategies may be passed that assess whether or not an attempt should be made.

Types

type Action

type Action func(attempt uint) error

Action defines a callable function that package retry can handle.