Documentation
¶
Overview ¶
Package retry is a library for retrying operations and backing off between tries
Index ¶
Examples ¶
Constants ¶
const ( // DefaultAttempts is the default number of retry attempts if left unconfigured DefaultAttempts = 10 // DefaultBackoffTime is the default wait time for retry attempts DefaultBackoffTime = 100 * time.Millisecond )
Variables ¶
This section is empty.
Functions ¶
func Do ¶
func Do(fn RetryableFunc, opts ...Option) error
Do executes the function provided and retries based on the options provided. The Default Options are:
- `Attempts(DefaultAttempts)` - `Delay(ConstantBackoff(DefaultBackoffTime))`
If all tries failed, the last erorr the function encountered is returned.
Example ¶
var i int
err := Do(func() error {
i++
if i > 3 {
fmt.Println("Success!")
return nil
}
return fmt.Errorf("failed")
},
Attempts(5),
Delay(ConstantBackoff(100*time.Millisecond)),
WithContext(context.Background()),
OnRetry(func(try uint, err error) {
fmt.Printf("onretry: %v on try %d\n", err, try)
return
}),
ForErrors(func(err error) bool {
return true // always retry
}),
)
if err != nil {
fmt.Println("error!")
}
Output: onretry: failed on try 1 onretry: failed on try 2 onretry: failed on try 3 Success!
Types ¶
type BackoffFunc ¶
BackoffFunc Computes the delay between retries on the given current retry number It may return 0 if try == 0, but try should always be called with try > 0
func ConstantBackoff ¶
func ConstantBackoff(delay time.Duration) BackoffFunc
ConstantBackoff always returns the same duration
func ExpontentialRandomBackoff ¶
func ExpontentialRandomBackoff(delay time.Duration, maxExp uint) BackoffFunc
ExpontentialRandomBackoff implements Exponential Random Backoff See: https://en.wikipedia.org/wiki/Exponential_backoff
Takes a delay (w) and a maxExp (E) Given: Try (n) Then: Delay (d) = w * RAND[0 to (2^MIN(n,E) - 1)]
type ErrorTestFunc ¶
ErrorTestFunc is the signature of a function that returns true if the next retry should be attempted, after inspection of the error
type OnRetryFunc ¶
OnRetryFunc is a function signature that is called before every retry with the current try number (starting from 1) and the last error from the previous attempt.
type Option ¶
type Option func(cfg *config)
Option configures retry options
func Attempts ¶
Attempts option configure the maximum number of retries beyond the initial attempt If attempts = 0, only the initial attempt will be run - this effectively disables retries
func Delay ¶
func Delay(backoff BackoffFunc) Option
Delay configures the backoff strategy for retries
func ForErrors ¶
func ForErrors(fn ErrorTestFunc) Option
ForErrors option configures which errors will be retried
func OnRetry ¶
func OnRetry(fn OnRetryFunc) Option
OnRetry option configures the function which is called after every failed attempt
func WithContext ¶
WithContext option configures the retry context This is used for early cancellation. On each round of try, the context object is check to see if it has expired. - If the context expires before the first try, then the ctx.Err() is returned - If the context expires at any other time, then the last error is returned
type RetryableFunc ¶
type RetryableFunc func() error
RetryableFunc is the signature of a function which can be retried by `retry.Do`
Source Files