Scott Baker | e7144bc | 2019-10-01 14:16:47 -0700 | [diff] [blame^] | 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 grpc |
| 20 | |
| 21 | import ( |
| 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. |
| 32 | type 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. |
| 43 | func 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}. |
| 56 | func 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. |
| 75 | func 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 | |
| 96 | func (ccr *ccResolverWrapper) resolveNow(o resolver.ResolveNowOption) { |
| 97 | ccr.resolver.ResolveNow(o) |
| 98 | } |
| 99 | |
| 100 | func (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. |
| 106 | func (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. |
| 121 | func (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 | |
| 131 | func (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 | } |