1/*
2 *
3 * Copyright 2017 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 manual defines a resolver that can be used to manually send resolved
20// addresses to ClientConn.
21package manual
22
23import (
24	"strconv"
25	"time"
26
27	"google.golang.org/grpc/resolver"
28)
29
30// NewBuilderWithScheme creates a new test resolver builder with the given scheme.
31func NewBuilderWithScheme(scheme string) *Resolver {
32	return &Resolver{
33		ResolveNowCallback: func(resolver.ResolveNowOptions) {},
34		scheme:             scheme,
35	}
36}
37
38// Resolver is also a resolver builder.
39// It's build() function always returns itself.
40type Resolver struct {
41	// ResolveNowCallback is called when the ResolveNow method is called on the
42	// resolver.  Must not be nil.  Must not be changed after the resolver may
43	// be built.
44	ResolveNowCallback func(resolver.ResolveNowOptions)
45	scheme             string
46
47	// Fields actually belong to the resolver.
48	CC             resolver.ClientConn
49	bootstrapState *resolver.State
50}
51
52// InitialState adds initial state to the resolver so that UpdateState doesn't
53// need to be explicitly called after Dial.
54func (r *Resolver) InitialState(s resolver.State) {
55	r.bootstrapState = &s
56}
57
58// Build returns itself for Resolver, because it's both a builder and a resolver.
59func (r *Resolver) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
60	r.CC = cc
61	if r.bootstrapState != nil {
62		r.UpdateState(*r.bootstrapState)
63	}
64	return r, nil
65}
66
67// Scheme returns the test scheme.
68func (r *Resolver) Scheme() string {
69	return r.scheme
70}
71
72// ResolveNow is a noop for Resolver.
73func (r *Resolver) ResolveNow(o resolver.ResolveNowOptions) {
74	r.ResolveNowCallback(o)
75}
76
77// Close is a noop for Resolver.
78func (*Resolver) Close() {}
79
80// UpdateState calls CC.UpdateState.
81func (r *Resolver) UpdateState(s resolver.State) {
82	r.CC.UpdateState(s)
83}
84
85// GenerateAndRegisterManualResolver generates a random scheme and a Resolver
86// with it. It also registers this Resolver.
87// It returns the Resolver and a cleanup function to unregister it.
88func GenerateAndRegisterManualResolver() (*Resolver, func()) {
89	scheme := strconv.FormatInt(time.Now().UnixNano(), 36)
90	r := NewBuilderWithScheme(scheme)
91	resolver.Register(r)
92	return r, func() { resolver.UnregisterForTesting(scheme) }
93}
94