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.
26package tap
27
28import (
29	"context"
30
31	"google.golang.org/grpc/metadata"
32)
33
34// Info defines the relevant information needed by the handles.
35type 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.
62type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error)