Sign inDemoInstall

Package Overview
File Explorer

Install Socket

Detect and block malicious and high-risk dependencies


Simple library for retry mechanism slightly inspired by [Try::Tiny::Retry]( http get with retry: [next examples]( * giantswarm/retry-go( - slightly complicated interface. * sethgrid/pester( - only http retry for http calls with retries and backoff * cenkalti/backoff( - Go port of the exponential backoff algorithm from Google's HTTP Client Library for Java. Really complicated interface. * rafaeljesus/retry-go( - looks good, slightly similar as this package, don't have 'simple' `Retry` method * matryer/try( - very popular package, nonintuitive interface (for me) 3.0.0 * `DelayTypeFunc` accepts a new parameter `err` - this breaking change affects only your custom Delay Functions. This change allow [make delay functions based on error](examples/delay_based_on_error_test.go). 1.0.2 -> 2.0.0 * argument of `retry.Delay` is final delay (no multiplication by `retry.Units` anymore) * function `retry.Units` are removed * [more about this breaking change]( 0.3.0 -> 1.0.0 * `retry.Retry` function are changed to `retry.Do` function * `retry.RetryCustom` (OnRetry) and `retry.RetryCustomWithOpts` functions are now implement via functions produces Options (aka `retry.OnRetry`)

Version published




Release Software License Travis AppVeyor Go Report Card GoDoc Sourcegraph

Simple library for retry mechanism

slightly inspired by Try::Tiny::Retry


http get with retry:

url := ""
var body []byte

err := retry.Do(
	func() error {
		resp, err := http.Get(url)
		if err != nil {
			return err
		defer resp.Body.Close()
		body, err = ioutil.ReadAll(resp.Body)
		if err != nil {
			return err

		return nil


next examples


  • giantswarm/retry-go - slightly complicated interface.

  • sethgrid/pester - only http retry for http calls with retries and backoff

  • cenkalti/backoff - Go port of the exponential backoff algorithm from Google's HTTP Client Library for Java. Really complicated interface.

  • rafaeljesus/retry-go - looks good, slightly similar as this package, don't have 'simple' Retry method

  • matryer/try - very popular package, nonintuitive interface (for me)



1.0.2 -> 2.0.0

0.3.0 -> 1.0.0

  • retry.Retry function are changed to retry.Do function

  • retry.RetryCustom (OnRetry) and retry.RetryCustomWithOpts functions are now implement via functions produces Options (aka retry.OnRetry)


var (
	DefaultAttempts      = uint(10)
	DefaultDelay         = 100 * time.Millisecond
	DefaultMaxJitter     = 100 * time.Millisecond
	DefaultOnRetry       = func(n uint, err error) {}
	DefaultRetryIf       = IsRecoverable
	DefaultDelayType     = CombineDelay(BackOffDelay, RandomDelay)
	DefaultLastErrorOnly = false
	DefaultContext       = context.Background()
func BackOffDelay
func BackOffDelay(n uint, _ error, config *Config) time.Duration

BackOffDelay is a DelayType which increases delay between consecutive retries

func Do
func Do(retryableFunc RetryableFunc, opts ...Option) error
func FixedDelay
func FixedDelay(_ uint, _ error, config *Config) time.Duration

FixedDelay is a DelayType which keeps delay the same through all iterations

func IsRecoverable
func IsRecoverable(err error) bool

IsRecoverable checks if error is an instance of unrecoverableError

func RandomDelay
func RandomDelay(_ uint, _ error, config *Config) time.Duration

RandomDelay is a DelayType which picks a random delay up to config.maxJitter

func Unrecoverable
func Unrecoverable(err error) error

Unrecoverable wraps an error in unrecoverableError struct

type Config
type Config struct {
type DelayTypeFunc
type DelayTypeFunc func(n uint, err error, config *Config) time.Duration

DelayTypeFunc is called to return the next delay to wait after the retriable function fails on err after n attempts.

func CombineDelay
func CombineDelay(delays ...DelayTypeFunc) DelayTypeFunc

CombineDelay is a DelayType the combines all of the specified delays into a new DelayTypeFunc

type Error
type Error []error

Error type represents list of errors in retry

func (Error) Error
func (e Error) Error() string

Error method return string representation of Error It is an implementation of error interface

func (Error) WrappedErrors
func (e Error) WrappedErrors() []error

WrappedErrors returns the list of errors that this Error is wrapping. It is an implementation of the errwrap.Wrapper interface in package errwrap so that retry.Error can be used with that library.

type OnRetryFunc
type OnRetryFunc func(n uint, err error)

Function signature of OnRetry function n = count of attempts

type Option
type Option func(*Config)

Option represents an option for retry.

func Attempts
func Attempts(attempts uint) Option

Attempts set count of retry default is 10

func Context
func Context(ctx context.Context) Option

Context allow to set context of retry default are Background context

example of immediately cancellation (maybe it isn't the best example, but it describes behavior enough; I hope)

ctx, cancel := context.WithCancel(context.Background())

	func() error {
func Delay
func Delay(delay time.Duration) Option

Delay set delay between retry default is 100ms

func DelayType
func DelayType(delayType DelayTypeFunc) Option

DelayType set type of the delay between retries default is BackOff

func LastErrorOnly
func LastErrorOnly(lastErrorOnly bool) Option

return the direct last error that came from the retried function default is false (return wrapped errors with everything)

func MaxDelay
func MaxDelay(maxDelay time.Duration) Option

MaxDelay set maximum delay between retry does not apply by default

func MaxJitter
func MaxJitter(maxJitter time.Duration) Option

MaxJitter sets the maximum random Jitter between retries for RandomDelay

func OnRetry
func OnRetry(onRetry OnRetryFunc) Option

OnRetry function callback are called each retry

log each retry example:

	func() error {
		return errors.New("some error")
	retry.OnRetry(func(n uint, err error) {
		log.Printf("#%d: %s\n", n, err)
func RetryIf
func RetryIf(retryIf RetryIfFunc) Option

RetryIf controls whether a retry should be attempted after an error (assuming there are any retry attempts remaining)

skip retry if special error example:

	func() error {
		return errors.New("special error")
	retry.RetryIf(func(err error) bool {
		if err.Error() == "special error" {
			return false
		return true

By default RetryIf stops execution if the error is wrapped using retry.Unrecoverable, so above example may also be shortened to:

	func() error {
		return retry.Unrecoverable(errors.New("special error"))
type RetryIfFunc
type RetryIfFunc func(error) bool

Function signature of retry if function

type RetryableFunc
type RetryableFunc func() error

Function signature of retryable function


Contributions are very much welcome.


Makefile provides several handy rules, like generator , setup for prepare build/dev environment, test, cover, etc...

Try make help for more information.

Before pull request

please try:

  • run tests (make test)
  • run linter (make lint)
  • if your IDE don't automaticaly do go fmt, run go fmt (make fmt)

README are generate from template .godocdown.tmpl and code documentation via godocdown.

Never edit direct, because your change will be lost.


Last updated on 13 Oct 2020

Did you know?

Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.


Related posts

SocketSocket SOC 2 Logo


  • Package Alerts
  • Integrations
  • Docs
  • Pricing
  • FAQ
  • Roadmap

Stay in touch

Get open source security insights delivered straight into your inbox.

  • Terms
  • Privacy
  • Security

Made with ⚡️ by Socket Inc