Vendor main dependencies.

vendor/google.golang.org/api/gensupport/backoff.go

@@ -0,0 +1,46 @@
+// 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
+}