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Simple golang library for retry mechanism
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README.md

retry

Release Software License Travis AppVeyor Go Report Card GoDoc codecov.io Sourcegraph

Simple library for retry mechanism

slightly inspired by Try::Tiny::Retry

SYNOPSIS

http get with retry:

url := "http://example.com"
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
	},
)

fmt.Println(body)

next examples

SEE ALSO

  • 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)

BREAKING CHANGES

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)

Usage

func BackOffDelay

func BackOffDelay(n uint, 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, config *config) time.Duration

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

type DelayTypeFunc

type DelayTypeFunc func(n uint, config *config) time.Duration

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 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 OnRetry

func OnRetry(onRetry OnRetryFunc) Option

OnRetry function callback are called each retry

log each retry example:

retry.Do(
	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:

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

type RetryIfFunc

type RetryIfFunc func(error) bool

Function signature of retry if function

type RetryableFunc

type RetryableFunc func() error

Function signature of retryable function

Contributing

Contributions are very much welcome.

Makefile

Makefile provides several handy rules, like README.md 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

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

Never edit README.md direct, because your change will be lost.

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