blob: 50991eafb91852673126905978520b679bd02557 [file] [log] [blame]
Scott Bakere7144bc2019-10-01 14:16:47 -07001/*
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
19package grpc
20
21import (
22 "fmt"
23 "strings"
24
25 "google.golang.org/grpc/grpclog"
26 "google.golang.org/grpc/internal/channelz"
27 "google.golang.org/grpc/resolver"
28)
29
30// ccResolverWrapper is a wrapper on top of cc for resolvers.
31// It implements resolver.ClientConnection interface.
32type ccResolverWrapper struct {
33 cc *ClientConn
34 resolver resolver.Resolver
35 addrCh chan []resolver.Address
36 scCh chan string
37 done chan struct{}
38 lastAddressesCount int
39}
40
41// split2 returns the values from strings.SplitN(s, sep, 2).
42// If sep is not found, it returns ("", "", false) instead.
43func split2(s, sep string) (string, string, bool) {
44 spl := strings.SplitN(s, sep, 2)
45 if len(spl) < 2 {
46 return "", "", false
47 }
48 return spl[0], spl[1], true
49}
50
51// parseTarget splits target into a struct containing scheme, authority and
52// endpoint.
53//
54// If target is not a valid scheme://authority/endpoint, it returns {Endpoint:
55// target}.
56func parseTarget(target string) (ret resolver.Target) {
57 var ok bool
58 ret.Scheme, ret.Endpoint, ok = split2(target, "://")
59 if !ok {
60 return resolver.Target{Endpoint: target}
61 }
62 ret.Authority, ret.Endpoint, ok = split2(ret.Endpoint, "/")
63 if !ok {
64 return resolver.Target{Endpoint: target}
65 }
66 return ret
67}
68
69// newCCResolverWrapper parses cc.target for scheme and gets the resolver
70// builder for this scheme and builds the resolver. The monitoring goroutine
71// for it is not started yet and can be created by calling start().
72//
73// If withResolverBuilder dial option is set, the specified resolver will be
74// used instead.
75func newCCResolverWrapper(cc *ClientConn) (*ccResolverWrapper, error) {
76 rb := cc.dopts.resolverBuilder
77 if rb == nil {
78 return nil, fmt.Errorf("could not get resolver for scheme: %q", cc.parsedTarget.Scheme)
79 }
80
81 ccr := &ccResolverWrapper{
82 cc: cc,
83 addrCh: make(chan []resolver.Address, 1),
84 scCh: make(chan string, 1),
85 done: make(chan struct{}),
86 }
87
88 var err error
89 ccr.resolver, err = rb.Build(cc.parsedTarget, ccr, resolver.BuildOption{DisableServiceConfig: cc.dopts.disableServiceConfig})
90 if err != nil {
91 return nil, err
92 }
93 return ccr, nil
94}
95
96func (ccr *ccResolverWrapper) resolveNow(o resolver.ResolveNowOption) {
97 ccr.resolver.ResolveNow(o)
98}
99
100func (ccr *ccResolverWrapper) close() {
101 ccr.resolver.Close()
102 close(ccr.done)
103}
104
105// NewAddress is called by the resolver implemenetion to send addresses to gRPC.
106func (ccr *ccResolverWrapper) NewAddress(addrs []resolver.Address) {
107 select {
108 case <-ccr.done:
109 return
110 default:
111 }
112 grpclog.Infof("ccResolverWrapper: sending new addresses to cc: %v", addrs)
113 if channelz.IsOn() {
114 ccr.addChannelzTraceEvent(addrs)
115 }
116 ccr.cc.handleResolvedAddrs(addrs, nil)
117}
118
119// NewServiceConfig is called by the resolver implemenetion to send service
120// configs to gRPC.
121func (ccr *ccResolverWrapper) NewServiceConfig(sc string) {
122 select {
123 case <-ccr.done:
124 return
125 default:
126 }
127 grpclog.Infof("ccResolverWrapper: got new service config: %v", sc)
128 ccr.cc.handleServiceConfig(sc)
129}
130
131func (ccr *ccResolverWrapper) addChannelzTraceEvent(addrs []resolver.Address) {
132 if len(addrs) == 0 && ccr.lastAddressesCount != 0 {
133 channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
134 Desc: "Resolver returns an empty address list",
135 Severity: channelz.CtWarning,
136 })
137 } else if len(addrs) != 0 && ccr.lastAddressesCount == 0 {
138 var s string
139 for i, a := range addrs {
140 if a.ServerName != "" {
141 s += a.Addr + "(" + a.ServerName + ")"
142 } else {
143 s += a.Addr
144 }
145 if i != len(addrs)-1 {
146 s += " "
147 }
148 }
149 channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
150 Desc: fmt.Sprintf("Resolver returns a non-empty address list (previous one was empty) %q", s),
151 Severity: channelz.CtINFO,
152 })
153 }
154 ccr.lastAddressesCount = len(addrs)
155}