/
backoff.go
78 lines (70 loc) · 2.44 KB
/
backoff.go
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// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"). You may
// not use this file except in compliance with the License. A copy of the
// License is located at
//
// http://aws.amazon.com/apache2.0/
//
// or in the "license" file accompanying this file. This file is distributed
// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
// express or implied. See the License for the specific language governing
// permissions and limitations under the License.
package retry
import (
"math"
"math/rand"
"sync"
"time"
)
// Backoff is the backoff interface
type Backoff interface {
Reset()
Duration() time.Duration
}
// SimpleBackoff is the default simple backoff
type SimpleBackoff struct {
current time.Duration
start time.Duration
max time.Duration
jitterMultiple float64
multiple float64
mu sync.Mutex
}
// NewSimpleBackoff creates a Backoff which ranges from min to max increasing by multiple each time.
// It also adds (and yes, the jitter is always added, never subtracted) a random amount of jitter up to jitterMultiple
// percent (that is, jitterMultiple = 0.0 is no jitter, 0.15 is 15% added jitter). The total time/ may exceed "max"
// when accounting for jitter, such that the absolute max is max + max * jitterMultiple
func NewSimpleBackoff(min, max time.Duration, jitterMultiple, multiple float64) *SimpleBackoff {
return &SimpleBackoff{
start: min,
current: min,
max: max,
jitterMultiple: jitterMultiple,
multiple: multiple,
}
}
// Duration gets the current duration including jitter
func (sb *SimpleBackoff) Duration() time.Duration {
sb.mu.Lock()
defer sb.mu.Unlock()
ret := sb.current
sb.current = time.Duration(math.Min(float64(sb.max.Nanoseconds()), float64(sb.current.Nanoseconds())*sb.multiple))
return AddJitter(ret, time.Duration(int64(float64(ret)*sb.jitterMultiple)))
}
// Reset resets the backoff
func (sb *SimpleBackoff) Reset() {
sb.mu.Lock()
defer sb.mu.Unlock()
sb.current = sb.start
}
// AddJitter adds an amount of jitter between 0 and the given jitter to the given duration
func AddJitter(duration time.Duration, jitter time.Duration) time.Duration {
var randJitter int64
if jitter.Nanoseconds() == 0 {
randJitter = 0
} else {
randJitter = rand.Int63n(jitter.Nanoseconds())
}
return time.Duration(duration.Nanoseconds() + randJitter)
}