README
¶
backoff
This is a fork from the awesome cenkalti/backoff which is a go port from google-http-java-client.
This BackOff sleeps upon BackOff() and calculates its next backoff time instead of returning the duration to sleep.
Exponential backoff is an algorithm that uses feedback to multiplicatively decrease the rate of some process, in order to gradually find an acceptable rate. The retries exponentially increase and stop increasing when a certain threshold is met.
Install
go get github.com/azr/backoff
Documentation
¶
Overview ¶
Package backoff helps you at backing off !
It was forked from github.com/cenkalti/backoff which is awesome.
This BackOff sleeps upon BackOff() and calculates its next backoff time instead of returning the duration to sleep.
Index ¶
Examples ¶
Constants ¶
const ( DefaultInitialInterval = 500 * time.Millisecond DefaultRandomizationFactor = 0.5 DefaultMultiplier = 1.5 DefaultMaxInterval = 60 * time.Second )
Default values for ExponentialBackOff.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ConstantBackOff ¶
func NewConstant ¶
func NewConstant(d time.Duration) *ConstantBackOff
func (*ConstantBackOff) BackOff ¶
func (b *ConstantBackOff) BackOff()
func (*ConstantBackOff) Reset ¶
func (b *ConstantBackOff) Reset()
type ExponentialBackOff ¶
type ExponentialBackOff struct {
InitialInterval time.Duration
MaxInterval time.Duration
RandomizationFactor float64
Multiplier float64
// contains filtered or unexported fields
}
ExponentialBackOff is an implementation of BackOff that increases it's back off period for each retry attempt using a randomization function that grows exponentially. Backoff() time is calculated using the following formula:
randomized_interval =
retry_interval * (random value in range [1 - randomization_factor, 1 + randomization_factor])
In other words BackOff() will sleep for times between the randomization factor percentage below and above the retry interval. For example, using 2 seconds as the base retry interval and 0.5 as the randomization factor, the actual back off period used in the next retry attempt will be between 1 and 3 seconds.
Note: max_interval caps the retry_interval and not the randomized_interval.
Example: The default retry_interval is .5 seconds, default randomization_factor is 0.5, default multiplier is 1.5 and the max_interval is set to 25 seconds. For 12 tries the sequence will sleep (values in seconds) (output from ExampleExpBackOffTimes) :
request# retry_interval randomized_interval 1 0.5 [0.25, 0.75] 2 0.75 [0.375, 1.125] 3 1.125 [0.562, 1.687] 4 1.687 [0.8435, 2.53] 5 2.53 [1.265, 3.795] 6 3.795 [1.897, 5.692] 7 5.692 [2.846, 8.538] 8 8.538 [4.269, 12.807] 9 12.807 [6.403, 19.210] 10 19.22 [9.611, 28.833] 11 25 [12.5, 37.5] 12 25 [12.5, 37.5]
Implementation is not thread-safe.
func NewExponential ¶
func NewExponential() *ExponentialBackOff
NewExponential creates an instance of ExponentialBackOff using default values.
Example (DefaultWaitingIntervals) ¶
package main
import (
"fmt"
"time"
"github.com/azr/backoff"
)
func main() {
exp := backoff.NewExponential()
for i := 0; i < 25; i++ {
d := exp.GetSleepTime()
fmt.Printf("Random duration was %2.2fs, interval: %2.2fs in [ %2.2fs , %2.2fs ]\n",
d.Seconds(),
exp.Inverval().Seconds(),
(exp.Inverval() - time.Duration(exp.RandomizationFactor*float64(exp.Inverval()))).Seconds(),
(exp.Inverval() + time.Duration(exp.RandomizationFactor*float64(exp.Inverval()))).Seconds(),
)
exp.IncrementCurrentInterval()
// exp.BackOff() would have executed time.Sleep(exp.GetSleepTime()) and exp.IncrementCurrentInterval()
}
}
Output: Random duration was 0.51s, interval: 0.50s in [ 0.25s , 0.75s ] Random duration was 0.99s, interval: 0.75s in [ 0.38s , 1.12s ] Random duration was 0.80s, interval: 1.12s in [ 0.56s , 1.69s ] Random duration was 1.49s, interval: 1.69s in [ 0.84s , 2.53s ] Random duration was 2.07s, interval: 2.53s in [ 1.27s , 3.80s ] Random duration was 3.68s, interval: 3.80s in [ 1.90s , 5.70s ] Random duration was 4.46s, interval: 5.70s in [ 2.85s , 8.54s ] Random duration was 6.78s, interval: 8.54s in [ 4.27s , 12.81s ] Random duration was 15.11s, interval: 12.81s in [ 6.41s , 19.22s ] Random duration was 13.81s, interval: 19.22s in [ 9.61s , 28.83s ] Random duration was 20.27s, interval: 28.83s in [ 14.42s , 43.25s ] Random duration was 37.23s, interval: 43.25s in [ 21.62s , 64.87s ] Random duration was 64.24s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 81.75s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 47.59s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 47.82s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 75.15s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 42.39s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 81.92s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 71.80s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 61.43s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 31.70s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 39.50s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 66.44s, interval: 60.00s in [ 30.00s , 90.00s ] Random duration was 88.51s, interval: 60.00s in [ 30.00s , 90.00s ]
func (*ExponentialBackOff) BackOff ¶
func (b *ExponentialBackOff) BackOff()
func (*ExponentialBackOff) GetSleepTime ¶
func (b *ExponentialBackOff) GetSleepTime() time.Duration
func (*ExponentialBackOff) IncrementCurrentInterval ¶
func (b *ExponentialBackOff) IncrementCurrentInterval()
Increments the current interval by multiplying it with the multiplier.
func (*ExponentialBackOff) Inverval ¶
func (b *ExponentialBackOff) Inverval() time.Duration
func (*ExponentialBackOff) Reset ¶
func (b *ExponentialBackOff) Reset()
Reset the interval back to the initial retry interval and restarts the timer.
type Interface ¶
type Interface interface {
// Example usage:
//
// for ;; {
// err, canRetry := somethingThatCanFail()
// if err != nil && canRetry {
// backoffer.Backoff()
// }
// }
BackOff()
// Reset to initial state.
Reset()
}
Interface interface to use after a retryable operation failed. A Interface.BackOff sleeps.
type LinearBackOff ¶
type LinearBackOff struct {
InitialInterval time.Duration
Multiplier float64
Increment time.Duration
MaxInterval time.Duration
// contains filtered or unexported fields
}
grows linearly until
func (*LinearBackOff) BackOff ¶
func (lb *LinearBackOff) BackOff()
func (*LinearBackOff) Reset ¶
func (lb *LinearBackOff) Reset()
type ZeroBackOff ¶
type ZeroBackOff struct{}
ZeroBackOff is a fixed back-off policy whose back-off time is always zero, meaning that the operation is retried immediately without waiting.
func (*ZeroBackOff) BackOff ¶
func (b *ZeroBackOff) BackOff()
func (*ZeroBackOff) Reset ¶
func (b *ZeroBackOff) Reset()
Source Files