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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"
- )
-
- // BackoffStrategy defines the set of functions that a backoff-er must
- // implement.
- 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
- }
-
- // Pause returns the amount of time the caller should wait.
- 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
- }
-
- // Reset resets the backoff strategy such that the next Pause call will begin
- // counting from the start. It is not safe to call concurrently with Pause.
- func (eb *ExponentialBackoff) Reset() {
- eb.n = 0
- eb.total = 0
- }
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