feat(grpc): initial grpc server. (#253)

* feat(grpc): initial grpc server.

* refactor(vendor): add missing vendor.

* fix testing

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

vendor/google.golang.org/grpc/tap/tap.go

@@ -0,0 +1,39 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * 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 tap defines the function handles which are executed on the transport
+// layer of gRPC-Go and related information. Everything here is EXPERIMENTAL.
+package tap
+
+import (
+	"golang.org/x/net/context"
+)
+
+// Info defines the relevant information needed by the handles.
+type Info struct {
+	// FullMethodName is the string of grpc method (in the format of
+	// /package.service/method).
+	FullMethodName string
+	// TODO: More to be added.
+}
+
+// ServerInHandle defines the function which runs when a new stream is created
+// on the server side. Note that it is executed in the per-connection I/O goroutine(s) instead
+// of per-RPC goroutine. Therefore, users should NOT have any blocking/time-consuming
+// work in this handle. Otherwise all the RPCs would slow down.
+type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error)