1 files changed, 51 insertions, 0 deletions

diff --git a/vendor/google.golang.org/api/gensupport/backoff.go b/vendor/google.golang.org/api/gensupport/backoff.go
new file mode 100644
index 0000000..94b7789
--- /dev/null
+++ b/vendor/google.golang.org/api/gensupport/backoff.go
@@ -0,0 +1,51 @@
+// 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
+}