Merge v1.2.1-master

Signed-off-by: Emile Vauge <emile@vauge.com>

vendor/github.com/cenk/backoff/retry.go

@@ -17,6 +17,9 @@ type Notify func(error, time.Duration)
 // o is guaranteed to be run at least once.
 // It is the caller's responsibility to reset b after Retry returns.
 //
+// If o returns a *PermanentError, the operation is not retried, and the
+// wrapped error is returned.
+//
 // Retry sleeps the goroutine for the duration returned by BackOff after a
 // failed operation returns.
 func Retry(o Operation, b BackOff) error { return RetryNotify(o, b, nil) }
@@ -27,12 +30,18 @@ func RetryNotify(operation Operation, b BackOff, notify Notify) error {
 	var err error
 	var next time.Duration
 
+	cb := ensureContext(b)
+
 	b.Reset()
 	for {
 		if err = operation(); err == nil {
 			return nil
 		}
 
+		if permanent, ok := err.(*PermanentError); ok {
+			return permanent.Err
+		}
+
 		if next = b.NextBackOff(); next == Stop {
 			return err
 		}
@@ -41,6 +50,29 @@ func RetryNotify(operation Operation, b BackOff, notify Notify) error {
 			notify(err, next)
 		}
 
-		time.Sleep(next)
+		t := time.NewTimer(next)
+
+		select {
+		case <-cb.Context().Done():
+			t.Stop()
+			return err
+		case <-t.C:
+		}
+	}
+}
+
+// PermanentError signals that the operation should not be retried.
+type PermanentError struct {
+	Err error
+}
+
+func (e *PermanentError) Error() string {
+	return e.Err.Error()
+}
+
+// Permanent wraps the given err in a *PermanentError.
+func Permanent(err error) *PermanentError {
+	return &PermanentError{
+		Err: err,
 	}
 }