1 /*
2 *
3 * Copyright 2016 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18 19 // Package tap defines the function handles which are executed on the transport
20 // layer of gRPC-Go and related information.
21 //
22 // # Experimental
23 //
24 // Notice: This API is EXPERIMENTAL and may be changed or removed in a
25 // later release.
26 package tap
27 28 import (
29 "context"
30 31 "google.golang.org/grpc/metadata"
32 )
33 34 // Info defines the relevant information needed by the handles.
35 type Info struct {
36 // FullMethodName is the string of grpc method (in the format of
37 // /package.service/method).
38 FullMethodName string
39 40 // Header contains the header metadata received.
41 Header metadata.MD
42 43 // TODO: More to be added.
44 }
45 46 // ServerInHandle defines the function which runs before a new stream is
47 // created on the server side. If it returns a non-nil error, the stream will
48 // not be created and an error will be returned to the client. If the error
49 // returned is a status error, that status code and message will be used,
50 // otherwise PermissionDenied will be the code and err.Error() will be the
51 // message.
52 //
53 // It's intended to be used in situations where you don't want to waste the
54 // resources to accept the new stream (e.g. rate-limiting). For other general
55 // usages, please use interceptors.
56 //
57 // Note that it is executed in the per-connection I/O goroutine(s) instead of
58 // per-RPC goroutine. Therefore, users should NOT have any
59 // blocking/time-consuming work in this handle. Otherwise all the RPCs would
60 // slow down. Also, for the same reason, this handle won't be called
61 // concurrently by gRPC.
62 type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error)
63