Implement gateway support Google Cloud Storage

vendor/cloud.google.com/go/storage/invoke.go

@@ -0,0 +1,43 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package storage
+
+import (
+	"cloud.google.com/go/internal"
+	gax "github.com/googleapis/gax-go"
+	"golang.org/x/net/context"
+	"google.golang.org/api/googleapi"
+)
+
+// runWithRetry calls the function until it returns nil or a non-retryable error, or
+// the context is done.
+func runWithRetry(ctx context.Context, call func() error) error {
+	return internal.Retry(ctx, gax.Backoff{}, func() (stop bool, err error) {
+		err = call()
+		if err == nil {
+			return true, nil
+		}
+		e, ok := err.(*googleapi.Error)
+		if !ok {
+			return true, err
+		}
+		// Retry on 429 and 5xx, according to
+		// https://cloud.google.com/storage/docs/exponential-backoff.
+		if e.Code == 429 || (e.Code >= 500 && e.Code < 600) {
+			return false, nil
+		}
+		return true, err
+	})
+}