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exponential.go
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exponential.go
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// Copyright 2020 The PipeCD Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License 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 backoff
import (
"math"
"math/rand"
"time"
)
type exponential struct {
base time.Duration
max time.Duration
calls int
rand *rand.Rand
}
func NewExponential(base, max time.Duration) Backoff {
return &exponential{
base: base,
max: max,
rand: rand.New(rand.NewSource(time.Now().UTC().UnixNano())),
}
}
// Implemented FullJitter algorithm
// https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/
func (b *exponential) Next() time.Duration {
defer func() {
b.calls++
}()
if b.calls == 0 {
return 0
}
d := math.Min(float64(b.max), float64(b.base)*math.Pow(2, float64(b.calls-1)))
d *= b.rand.Float64()
return time.Duration(d)
}
func (b *exponential) Calls() int {
return b.calls
}
func (b *exponential) Reset() {
b.calls = 0
}
func (b *exponential) Clone() Backoff {
return &exponential{
base: b.base,
max: b.max,
rand: b.rand,
}
}