-
Notifications
You must be signed in to change notification settings - Fork 4.3k
/
resolver.go
158 lines (141 loc) · 5.26 KB
/
resolver.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
/*
*
* Copyright 2017 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 resolver defines APIs for name resolution in gRPC.
// All APIs in this package are experimental.
package resolver
var (
// m is a map from scheme to resolver builder.
m = make(map[string]Builder)
// defaultScheme is the default scheme to use.
defaultScheme = "passthrough"
)
// TODO(bar) install dns resolver in init(){}.
// Register registers the resolver builder to the resolver map. b.Scheme will be
// used as the scheme registered with this builder.
//
// NOTE: this function must only be called during initialization time (i.e. in
// an init() function), and is not thread-safe. If multiple Resolvers are
// registered with the same name, the one registered last will take effect.
func Register(b Builder) {
m[b.Scheme()] = b
}
// Get returns the resolver builder registered with the given scheme.
//
// If no builder is register with the scheme, nil will be returned.
func Get(scheme string) Builder {
if b, ok := m[scheme]; ok {
return b
}
return nil
}
// SetDefaultScheme sets the default scheme that will be used. The default
// default scheme is "passthrough".
//
// NOTE: this function must only be called during initialization time (i.e. in
// an init() function), and is not thread-safe. The scheme set last overrides
// previously set values.
func SetDefaultScheme(scheme string) {
defaultScheme = scheme
}
// GetDefaultScheme gets the default scheme that will be used.
func GetDefaultScheme() string {
return defaultScheme
}
// AddressType indicates the address type returned by name resolution.
type AddressType uint8
const (
// Backend indicates the address is for a backend server.
Backend AddressType = iota
// GRPCLB indicates the address is for a grpclb load balancer.
GRPCLB
)
// Address represents a server the client connects to.
// This is the EXPERIMENTAL API and may be changed or extended in the future.
type Address struct {
// Addr is the server address on which a connection will be established.
Addr string
// Type is the type of this address.
Type AddressType
// ServerName is the name of this address.
//
// e.g. if Type is GRPCLB, ServerName should be the name of the remote load
// balancer, not the name of the backend.
ServerName string
// Metadata is the information associated with Addr, which may be used
// to make load balancing decision.
Metadata interface{}
}
// BuildOption includes additional information for the builder to create
// the resolver.
type BuildOption struct {
// DisableServiceConfig indicates whether resolver should fetch service config data.
DisableServiceConfig bool
}
// ClientConn contains the callbacks for resolver to notify any updates
// to the gRPC ClientConn.
//
// This interface is to be implemented by gRPC. Users should not need a
// brand new implementation of this interface. For the situations like
// testing, the new implementation should embed this interface. This allows
// gRPC to add new methods to this interface.
type ClientConn interface {
// NewAddress is called by resolver to notify ClientConn a new list
// of resolved addresses.
// The address list should be the complete list of resolved addresses.
NewAddress(addresses []Address)
// NewServiceConfig is called by resolver to notify ClientConn a new
// service config. The service config should be provided as a json string.
NewServiceConfig(serviceConfig string)
}
// Target represents a target for gRPC, as specified in:
// https://github.com/grpc/grpc/blob/master/doc/naming.md.
type Target struct {
Scheme string
Authority string
Endpoint string
}
// Builder creates a resolver that will be used to watch name resolution updates.
type Builder interface {
// Build creates a new resolver for the given target.
//
// gRPC dial calls Build synchronously, and fails if the returned error is
// not nil.
Build(target Target, cc ClientConn, opts BuildOption) (Resolver, error)
// Scheme returns the scheme supported by this resolver.
// Scheme is defined at https://github.com/grpc/grpc/blob/master/doc/naming.md.
Scheme() string
}
// ResolveNowOption includes additional information for ResolveNow.
type ResolveNowOption struct{}
// Resolver watches for the updates on the specified target.
// Updates include address updates and service config updates.
type Resolver interface {
// ResolveNow will be called by gRPC to try to resolve the target name
// again. It's just a hint, resolver can ignore this if it's not necessary.
//
// It could be called multiple times concurrently.
ResolveNow(ResolveNowOption)
// Close closes the resolver.
Close()
}
// UnregisterForTesting removes the resolver builder with the given scheme from the
// resolver map.
// This function is for testing only.
func UnregisterForTesting(scheme string) {
delete(m, scheme)
}