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