1 | /*
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2 | * Copyright 2019 gRPC authors.
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | */
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17 |
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18 | import { MethodConfig, ServiceConfig } from './service-config';
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19 | import { StatusObject } from './call-stream';
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20 | import { SubchannelAddress } from './subchannel-address';
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21 | import { GrpcUri, uriToString } from './uri-parser';
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22 | import { ChannelOptions } from './channel-options';
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23 | import { Metadata } from './metadata';
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24 | import { Status } from './constants';
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25 | import { Filter, FilterFactory } from './filter';
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26 |
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27 | export interface CallConfig {
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28 | methodConfig: MethodConfig;
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29 | onCommitted?: () => void;
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30 | pickInformation: { [key: string]: string };
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31 | status: Status;
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32 | dynamicFilterFactories: FilterFactory<Filter>[];
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33 | }
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34 |
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35 | /**
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36 | * Selects a configuration for a method given the name and metadata. Defined in
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37 | * https://github.com/grpc/proposal/blob/master/A31-xds-timeout-support-and-config-selector.md#new-functionality-in-grpc
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38 | */
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39 | export interface ConfigSelector {
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40 | (methodName: string, metadata: Metadata): CallConfig;
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41 | }
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42 |
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43 | /**
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44 | * A listener object passed to the resolver's constructor that provides name
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45 | * resolution updates back to the resolver's owner.
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46 | */
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47 | export interface ResolverListener {
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48 | /**
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49 | * Called whenever the resolver has new name resolution results to report
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50 | * @param addressList The new list of backend addresses
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51 | * @param serviceConfig The new service configuration corresponding to the
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52 | * `addressList`. Will be `null` if no service configuration was
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53 | * retrieved or if the service configuration was invalid
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54 | * @param serviceConfigError If non-`null`, indicates that the retrieved
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55 | * service configuration was invalid
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56 | */
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57 | onSuccessfulResolution(
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58 | addressList: SubchannelAddress[],
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59 | serviceConfig: ServiceConfig | null,
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60 | serviceConfigError: StatusObject | null,
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61 | configSelector: ConfigSelector | null,
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62 | attributes: { [key: string]: unknown }
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63 | ): void;
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64 | /**
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65 | * Called whenever a name resolution attempt fails.
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66 | * @param error Describes how resolution failed
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67 | */
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68 | onError(error: StatusObject): void;
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69 | }
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70 |
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71 | /**
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72 | * A resolver class that handles one or more of the name syntax schemes defined
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73 | * in the [gRPC Name Resolution document](https://github.com/grpc/grpc/blob/master/doc/naming.md)
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74 | */
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75 | export interface Resolver {
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76 | /**
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77 | * Indicates that the caller wants new name resolution data. Calling this
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78 | * function may eventually result in calling one of the `ResolverListener`
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79 | * functions, but that is not guaranteed. Those functions will never be
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80 | * called synchronously with the constructor or updateResolution.
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81 | */
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82 | updateResolution(): void;
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83 |
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84 | /**
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85 | * Destroy the resolver. Should be called when the owning channel shuts down.
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86 | */
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87 | destroy(): void;
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88 | }
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89 |
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90 | export interface ResolverConstructor {
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91 | new (
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92 | target: GrpcUri,
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93 | listener: ResolverListener,
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94 | channelOptions: ChannelOptions
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95 | ): Resolver;
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96 | /**
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97 | * Get the default authority for a target. This loosely corresponds to that
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98 | * target's hostname. Throws an error if this resolver class cannot parse the
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99 | * `target`.
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100 | * @param target
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101 | */
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102 | getDefaultAuthority(target: GrpcUri): string;
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103 | }
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104 |
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105 | const registeredResolvers: { [scheme: string]: ResolverConstructor } = {};
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106 | let defaultScheme: string | null = null;
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107 |
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108 | /**
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109 | * Register a resolver class to handle target names prefixed with the `prefix`
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110 | * string. This prefix should correspond to a URI scheme name listed in the
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111 | * [gRPC Name Resolution document](https://github.com/grpc/grpc/blob/master/doc/naming.md)
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112 | * @param prefix
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113 | * @param resolverClass
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114 | */
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115 | export function registerResolver(
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116 | scheme: string,
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117 | resolverClass: ResolverConstructor
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118 | ) {
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119 | registeredResolvers[scheme] = resolverClass;
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120 | }
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121 |
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122 | /**
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123 | * Register a default resolver to handle target names that do not start with
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124 | * any registered prefix.
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125 | * @param resolverClass
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126 | */
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127 | export function registerDefaultScheme(scheme: string) {
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128 | defaultScheme = scheme;
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129 | }
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130 |
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131 | /**
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132 | * Create a name resolver for the specified target, if possible. Throws an
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133 | * error if no such name resolver can be created.
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134 | * @param target
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135 | * @param listener
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136 | */
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137 | export function createResolver(
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138 | target: GrpcUri,
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139 | listener: ResolverListener,
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140 | options: ChannelOptions
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141 | ): Resolver {
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142 | if (target.scheme !== undefined && target.scheme in registeredResolvers) {
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143 | return new registeredResolvers[target.scheme](target, listener, options);
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144 | } else {
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145 | throw new Error(
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146 | `No resolver could be created for target ${uriToString(target)}`
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147 | );
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148 | }
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149 | }
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150 |
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151 | /**
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152 | * Get the default authority for the specified target, if possible. Throws an
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153 | * error if no registered name resolver can parse that target string.
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154 | * @param target
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155 | */
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156 | export function getDefaultAuthority(target: GrpcUri): string {
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157 | if (target.scheme !== undefined && target.scheme in registeredResolvers) {
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158 | return registeredResolvers[target.scheme].getDefaultAuthority(target);
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159 | } else {
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160 | throw new Error(`Invalid target ${uriToString(target)}`);
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161 | }
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162 | }
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163 |
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164 | export function mapUriDefaultScheme(target: GrpcUri): GrpcUri | null {
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165 | if (target.scheme === undefined || !(target.scheme in registeredResolvers)) {
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166 | if (defaultScheme !== null) {
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167 | return {
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168 | scheme: defaultScheme,
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169 | authority: undefined,
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170 | path: uriToString(target),
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171 | };
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172 | } else {
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173 | return null;
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174 | }
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175 | }
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176 | return target;
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177 | }
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