forked from TrueCloudLab/lego
67 lines
2.1 KiB
Go
67 lines
2.1 KiB
Go
|
// Package backoff implements backoff algorithms for retrying operations.
|
||
|
|
//
|
||
|
|
// Use Retry function for retrying operations that may fail.
|
||
|
|
// If Retry does not meet your needs,
|
||
|
|
// copy/paste the function into your project and modify as you wish.
|
||
|
|
//
|
||
|
|
// There is also Ticker type similar to time.Ticker.
|
||
|
|
// You can use it if you need to work with channels.
|
||
|
|
//
|
||
|
|
// See Examples section below for usage examples.
|
||
|
|
package backoff
|
||
|
|
|
||
|
|
import "time"
|
||
|
|
|
||
|
|
// BackOff is a backoff policy for retrying an operation.
|
||
|
|
type BackOff interface {
|
||
|
|
// NextBackOff returns the duration to wait before retrying the operation,
|
||
|
|
// or backoff. Stop to indicate that no more retries should be made.
|
||
|
|
//
|
||
|
|
// Example usage:
|
||
|
|
//
|
||
|
|
// duration := backoff.NextBackOff();
|
||
|
|
// if (duration == backoff.Stop) {
|
||
|
|
// // Do not retry operation.
|
||
|
|
// } else {
|
||
|
|
// // Sleep for duration and retry operation.
|
||
|
|
// }
|
||
|
|
//
|
||
|
|
NextBackOff() time.Duration
|
||
|
|
|
||
|
|
// Reset to initial state.
|
||
|
|
Reset()
|
||
|
|
}
|
||
|
|
|
||
|
|
// Stop indicates that no more retries should be made for use in NextBackOff().
|
||
|
|
const Stop time.Duration = -1
|
||
|
|
|
||
|
|
// ZeroBackOff is a fixed backoff policy whose backoff time is always zero,
|
||
|
|
// meaning that the operation is retried immediately without waiting, indefinitely.
|
||
|
|
type ZeroBackOff struct{}
|
||
|
|
|
||
|
|
func (b *ZeroBackOff) Reset() {}
|
||
|
|
|
||
|
|
func (b *ZeroBackOff) NextBackOff() time.Duration { return 0 }
|
||
|
|
|
||
|
|
// StopBackOff is a fixed backoff policy that always returns backoff.Stop for
|
||
|
|
// NextBackOff(), meaning that the operation should never be retried.
|
||
|
|
type StopBackOff struct{}
|
||
|
|
|
||
|
|
func (b *StopBackOff) Reset() {}
|
||
|
|
|
||
|
|
func (b *StopBackOff) NextBackOff() time.Duration { return Stop }
|
||
|
|
|
||
|
|
// ConstantBackOff is a backoff policy that always returns the same backoff delay.
|
||
|
|
// This is in contrast to an exponential backoff policy,
|
||
|
|
// which returns a delay that grows longer as you call NextBackOff() over and over again.
|
||
|
|
type ConstantBackOff struct {
|
||
|
|
Interval time.Duration
|
||
|
|
}
|
||
|
|
|
||
|
|
func (b *ConstantBackOff) Reset() {}
|
||
|
|
func (b *ConstantBackOff) NextBackOff() time.Duration { return b.Interval }
|
||
|
|
|
||
|
|
func NewConstantBackOff(d time.Duration) *ConstantBackOff {
|
||
|
|
return &ConstantBackOff{Interval: d}
|
||
|
|
}
|