github.com/avast/retry-go
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
},
)
fmt.Println(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)
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.1.0.2 -> 2.0.0
argument of retry.Delay is final delay (no multiplication by retry.Units
anymore)
function retry.Units are removed
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(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 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) Error() string
Error method return string representation of Error It is an implementation of error interface
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(n uint, err error)
Function signature of OnRetry function n = count of attempts
type Option func(*Config)
Option represents an option for retry.
func Attempts(attempts uint) Option
Attempts set count of retry default is 10
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"))
}
)
type RetryIfFunc func(error) bool
Function signature of retry if function
type RetryableFunc func() error
Function signature of retryable function
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.
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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