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exponential_backoff.go
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exponential_backoff.go
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// Copyright 2014-2019 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"
"sync"
"time"
)
type ExponentialBackoff 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. (t = start * multiple * n for the nth iteration)
// 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 * jiterMultiple
func NewExponentialBackoff(min, max time.Duration, jitterMultiple, multiple float64) *ExponentialBackoff {
return &ExponentialBackoff{
start: min,
current: min,
max: max,
jitterMultiple: jitterMultiple,
multiple: multiple,
}
}
func (sb *ExponentialBackoff) 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)))
}
func (sb *ExponentialBackoff) Reset() {
sb.mu.Lock()
defer sb.mu.Unlock()
sb.current = sb.start
}