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restic/vendor/github.com/cenkalti/backoff/backoff.go
2017-10-14 15:56:25 +02:00

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}
}