diff --git a/vendor/google.golang.org/grpc/tap/tap.go b/vendor/google.golang.org/grpc/tap/tap.go
new file mode 100644
index 0000000..584360f
--- /dev/null
+++ b/vendor/google.golang.org/grpc/tap/tap.go
@@ -0,0 +1,51 @@
+/*
+ *
+ * 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 (
+	"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 before a new stream is created
+// on the server side. If it returns a non-nil error, the stream will not be
+// created and a RST_STREAM will be sent back to the client with REFUSED_STREAM.
+// The client will receive an RPC error "code = Unavailable, desc = stream
+// terminated by RST_STREAM with error code: REFUSED_STREAM".
+//
+// It's intended to be used in situations where you don't want to waste the
+// resources to accept the new stream (e.g. rate-limiting). And the content of
+// the error will be ignored and won't be sent back to the client. For other
+// general usages, please use interceptors.
+//
+// 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. Also, for the same reason, this handle won't be called
+// concurrently by gRPC.
+type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error)