Update GCS storage library to support GetObject API on gzipped objects (#6506)

Fixes #6280

vendor/cloud.google.com/go/internal/trace/go18.go

@@ -0,0 +1,83 @@
+// Copyright 2018 Google LLC
+//
+// 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.
+
+// +build go1.8
+
+package trace
+
+import (
+	"go.opencensus.io/trace"
+	"golang.org/x/net/context"
+	"google.golang.org/api/googleapi"
+	"google.golang.org/genproto/googleapis/rpc/code"
+	"google.golang.org/grpc/status"
+)
+
+func StartSpan(ctx context.Context, name string) context.Context {
+	ctx, _ = trace.StartSpan(ctx, name)
+	return ctx
+}
+
+func EndSpan(ctx context.Context, err error) {
+	span := trace.FromContext(ctx)
+	if err != nil {
+		span.SetStatus(toStatus(err))
+	}
+	span.End()
+}
+
+// ToStatus interrogates an error and converts it to an appropriate
+// OpenCensus status.
+func toStatus(err error) trace.Status {
+	if err2, ok := err.(*googleapi.Error); ok {
+		return trace.Status{Code: httpStatusCodeToOCCode(err2.Code), Message: err2.Message}
+	} else if s, ok := status.FromError(err); ok {
+		return trace.Status{Code: int32(s.Code()), Message: s.Message()}
+	} else {
+		return trace.Status{Code: int32(code.Code_UNKNOWN), Message: err.Error()}
+	}
+}
+
+// TODO (deklerk): switch to using OpenCensus function when it becomes available.
+// Reference: https://github.com/googleapis/googleapis/blob/26b634d2724ac5dd30ae0b0cbfb01f07f2e4050e/google/rpc/code.proto
+func httpStatusCodeToOCCode(httpStatusCode int) int32 {
+	switch httpStatusCode {
+	case 200:
+		return int32(code.Code_OK)
+	case 499:
+		return int32(code.Code_CANCELLED)
+	case 500:
+		return int32(code.Code_UNKNOWN) // Could also be Code_INTERNAL, Code_DATA_LOSS
+	case 400:
+		return int32(code.Code_INVALID_ARGUMENT) // Could also be Code_OUT_OF_RANGE
+	case 504:
+		return int32(code.Code_DEADLINE_EXCEEDED)
+	case 404:
+		return int32(code.Code_NOT_FOUND)
+	case 409:
+		return int32(code.Code_ALREADY_EXISTS) // Could also be Code_ABORTED
+	case 403:
+		return int32(code.Code_PERMISSION_DENIED)
+	case 401:
+		return int32(code.Code_UNAUTHENTICATED)
+	case 429:
+		return int32(code.Code_RESOURCE_EXHAUSTED)
+	case 501:
+		return int32(code.Code_UNIMPLEMENTED)
+	case 503:
+		return int32(code.Code_UNAVAILABLE)
+	default:
+		return int32(code.Code_UNKNOWN)
+	}
+}

vendor/cloud.google.com/go/internal/trace/not_go18.go

@@ -0,0 +1,30 @@
+// Copyright 2018 Google LLC
+//
+// 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.
+
+// +build !go1.8
+
+package trace
+
+import (
+	"golang.org/x/net/context"
+)
+
+// OpenCensus only supports go 1.8 and higher.
+
+func StartSpan(ctx context.Context, _ string) context.Context {
+	return ctx
+}
+
+func EndSpan(context.Context, error) {
+}