github.com/avast/retry-go/v4
Simple library for retry mechanism
Slightly inspired by Try::Tiny::Retry
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
},
)
if err != nil {
// handle error
}
fmt.Println(string(body))
HTTP GET with retry with data:
url := "http://example.com"
body, err := retry.DoWithData(
func() ([]byte, error) {
resp, err := http.Get(url)
if err != nil {
return nil, err
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, err
}
return body, nil
},
)
if err != nil {
// handle error
}
fmt.Println(string(body))
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)
4.0.0
Attempts(0) by PR #493.0.0
DelayTypeFunc accepts a new parameter err - this breaking change affects only your custom Delay Functions. This change allow make delay functions based on error.1.0.2 -> 2.0.0
retry.Delay is final delay (no multiplication by retry.Units anymore)retry.Units are removed0.3.0 -> 1.0.0
retry.Retry function are changed to retry.Do functionretry.RetryCustom (OnRetry) and retry.RetryCustomWithOpts functions are now implement via functions produces Options (aka retry.OnRetry)func BackOffDelay(n uint, _ error, config *Config) time.Duration
BackOffDelay is a DelayType which increases delay between consecutive retries
func Do(retryableFunc RetryableFunc, opts ...Option) error
func DoWithData[T any](retryableFunc RetryableFuncWithData[T], opts ...Option) (T, error)
func FixedDelay(_ uint, _ error, config *Config) time.Duration
FixedDelay is a DelayType which keeps delay the same through all iterations
func IsRecoverable(err error) bool
IsRecoverable checks if error is an instance of unrecoverableError
func RandomDelay(_ uint, _ error, config *Config) time.Duration
RandomDelay is a DelayType which picks a random delay up to config.maxJitter
func Unrecoverable(err error) error
Unrecoverable wraps an error in unrecoverableError struct
type Config struct {
}
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(delays ...DelayTypeFunc) DelayTypeFunc
CombineDelay is a DelayType the combines all of the specified delays into a new DelayTypeFunc
type Error []error
Error type represents list of errors in retry
func (e Error) As(target interface{}) bool
func (e Error) Error() string
Error method return string representation of Error It is an implementation of error interface
func (e Error) Is(target error) bool
func (e Error) Unwrap() error
Unwrap the last error for compatibility with errors.Unwrap(). When you need to
unwrap all errors, you should use WrappedErrors() instead.
err := Do(
func() error {
return errors.New("original error")
},
Attempts(1),
)
fmt.Println(errors.Unwrap(err)) # "original error" is printed
Added in version 4.2.0.
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 func(attempt uint, err error)
Function signature of OnRetry function
type Option func(*Config)
Option represents an option for retry.
func Attempts(attempts uint) Option
Attempts set count of retry. Setting to 0 will retry until the retried function succeeds. default is 10
func AttemptsForError(attempts uint, err error) Option
AttemptsForError sets count of retry in case execution results in given err
Retries for the given err are also counted against total retries. The retry
will stop if any of given retries is exhausted.
added in 4.3.0
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())
cancel()
retry.Do(
func() error {
...
},
retry.Context(ctx),
)
func Delay(delay time.Duration) Option
Delay set delay between retry default is 100ms
func DelayType(delayType DelayTypeFunc) Option
DelayType set type of the delay between retries default is BackOff
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(maxDelay time.Duration) Option
MaxDelay set maximum delay between retry does not apply by default
func MaxJitter(maxJitter time.Duration) Option
MaxJitter sets the maximum random Jitter between retries for RandomDelay
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(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
})
)
By default RetryIf stops execution if the error is wrapped using
retry.Unrecoverable, so above example may also be shortened to:
retry.Do(
func() error {
return retry.Unrecoverable(errors.New("special error"))
}
)
func UntilSucceeded() Option
UntilSucceeded will retry until the retried function succeeds. Equivalent to setting Attempts(0).
func WithTimer(t Timer) Option
WithTimer provides a way to swap out timer module implementations. This primarily is useful for mocking/testing, where you may not want to explicitly wait for a set duration for retries.
example of augmenting time.After with a print statement
type struct MyTimer {}
func (t *MyTimer) After(d time.Duration) <- chan time.Time {
fmt.Print("Timer called!")
return time.After(d)
}
retry.Do(
func() error { ... },
retry.WithTimer(&MyTimer{})
)
func WrapContextErrorWithLastError(wrapContextErrorWithLastError bool) Option
WrapContextErrorWithLastError allows the context error to be returned wrapped with the last error that the retried function returned. This is only applicable when Attempts is set to 0 to retry indefinitly and when using a context to cancel / timeout
default is false
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
retry.Do(
func() error {
...
},
retry.Context(ctx),
retry.Attempts(0),
retry.WrapContextErrorWithLastError(true),
)
type RetryIfFunc func(error) bool
Function signature of retry if function
type RetryableFunc func() error
Function signature of retryable function
type RetryableFuncWithData[T any] func() (T, error)
Function signature of retryable function with data
type Timer interface {
After(time.Duration) <-chan time.Time
}
Timer represents the timer used to track time for a retry.
Contributions are very much welcome.
Makefile provides several handy rules, like README.md generator , setup for prepare build/dev environment, test, cover, etc...
Try make help for more information.
maybe you need
make setupin order to setup environment
please try:
make test)make lint)go fmt, run go fmt (make fmt)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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