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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gensupport
import (
"math/rand"
"time"
)
type BackoffStrategy interface {
// Pause returns the duration of the next pause and true if the operation should be
// retried, or false if no further retries should be attempted.
Pause() (time.Duration, bool)
// Reset restores the strategy to its initial state.
Reset()
}
// ExponentialBackoff performs exponential backoff as per https://en.wikipedia.org/wiki/Exponential_backoff.
// The initial pause time is given by Base.
// Once the total pause time exceeds Max, Pause will indicate no further retries.
type ExponentialBackoff struct {
Base time.Duration
Max time.Duration
total time.Duration
n uint
}
func (eb *ExponentialBackoff) Pause() (time.Duration, bool) {
if eb.total > eb.Max {
return 0, false
}
// The next pause is selected from randomly from [0, 2^n * Base).
d := time.Duration(rand.Int63n((1 << eb.n) * int64(eb.Base)))
eb.total += d
eb.n++
return d, true
}
func (eb *ExponentialBackoff) Reset() {
eb.n = 0
eb.total = 0
}
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