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		scheme: scheme,
34	}
35}
36
37// Resolver is also a resolver builder.
38// It's build() function always returns itself.
39type Resolver struct {
40	scheme string
41
42	// Fields actually belong to the resolver.
43	cc             resolver.ClientConn
44	bootstrapState *resolver.State
45}
46
47// InitialState adds initial state to the resolver so that UpdateState doesn't
48// need to be explicitly called after Dial.
49func (r *Resolver) InitialState(s resolver.State) {
50	r.bootstrapState = &s
51}
52
53// Build returns itself for Resolver, because it's both a builder and a resolver.
54func (r *Resolver) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOption) (resolver.Resolver, error) {
55	r.cc = cc
56	if r.bootstrapState != nil {
57		r.UpdateState(*r.bootstrapState)
58	}
59	return r, nil
60}
61
62// Scheme returns the test scheme.
63func (r *Resolver) Scheme() string {
64	return r.scheme
65}
66
67// ResolveNow is a noop for Resolver.
68func (*Resolver) ResolveNow(o resolver.ResolveNowOption) {}
69
70// Close is a noop for Resolver.
71func (*Resolver) Close() {}
72
73// UpdateState calls cc.UpdateState.
74func (r *Resolver) UpdateState(s resolver.State) {
75	r.cc.UpdateState(s)
76}
77
78// GenerateAndRegisterManualResolver generates a random scheme and a Resolver
79// with it. It also registers this Resolver.
80// It returns the Resolver and a cleanup function to unregister it.
81func GenerateAndRegisterManualResolver() (*Resolver, func()) {
82	scheme := strconv.FormatInt(time.Now().UnixNano(), 36)
83	r := NewBuilderWithScheme(scheme)
84	resolver.Register(r)
85	return r, func() { resolver.UnregisterForTesting(scheme) }
86}
87