Initial Commit

node_modules/@grpc/grpc-js/src/resolver.ts

@@ -0,0 +1,180 @@
+/*
+ * Copyright 2019 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.
+ *
+ */
+
+import { MethodConfig, ServiceConfig } from './service-config';
+import { StatusObject } from './call-interface';
+import { SubchannelAddress } from './subchannel-address';
+import { GrpcUri, uriToString } from './uri-parser';
+import { ChannelOptions } from './channel-options';
+import { Metadata } from './metadata';
+import { Status } from './constants';
+import { Filter, FilterFactory } from './filter';
+
+export interface CallConfig {
+  methodConfig: MethodConfig;
+  onCommitted?: () => void;
+  pickInformation: { [key: string]: string };
+  status: Status;
+  dynamicFilterFactories: FilterFactory<Filter>[];
+}
+
+/**
+ * Selects a configuration for a method given the name and metadata. Defined in
+ * https://github.com/grpc/proposal/blob/master/A31-xds-timeout-support-and-config-selector.md#new-functionality-in-grpc
+ */
+export interface ConfigSelector {
+  (methodName: string, metadata: Metadata): CallConfig;
+}
+
+/**
+ * A listener object passed to the resolver's constructor that provides name
+ * resolution updates back to the resolver's owner.
+ */
+export interface ResolverListener {
+  /**
+   * Called whenever the resolver has new name resolution results to report
+   * @param addressList The new list of backend addresses
+   * @param serviceConfig The new service configuration corresponding to the
+   *     `addressList`. Will be `null` if no service configuration was
+   *     retrieved or if the service configuration was invalid
+   * @param serviceConfigError If non-`null`, indicates that the retrieved
+   *     service configuration was invalid
+   */
+  onSuccessfulResolution(
+    addressList: SubchannelAddress[],
+    serviceConfig: ServiceConfig | null,
+    serviceConfigError: StatusObject | null,
+    configSelector: ConfigSelector | null,
+    attributes: { [key: string]: unknown }
+  ): void;
+  /**
+   * Called whenever a name resolution attempt fails.
+   * @param error Describes how resolution failed
+   */
+  onError(error: StatusObject): void;
+}
+
+/**
+ * A resolver class that handles one or more of the name syntax schemes defined
+ * in the [gRPC Name Resolution document](https://github.com/grpc/grpc/blob/master/doc/naming.md)
+ */
+export interface Resolver {
+  /**
+   * Indicates that the caller wants new name resolution data. Calling this
+   * function may eventually result in calling one of the `ResolverListener`
+   * functions, but that is not guaranteed. Those functions will never be
+   * called synchronously with the constructor or updateResolution.
+   */
+  updateResolution(): void;
+
+  /**
+   * Discard all resources owned by the resolver. A later call to
+   * `updateResolution` should reinitialize those resources.  No
+   * `ResolverListener` callbacks should be called after `destroy` is called
+   * until `updateResolution` is called again.
+   */
+  destroy(): void;
+}
+
+export interface ResolverConstructor {
+  new (
+    target: GrpcUri,
+    listener: ResolverListener,
+    channelOptions: ChannelOptions
+  ): Resolver;
+  /**
+   * Get the default authority for a target. This loosely corresponds to that
+   * target's hostname. Throws an error if this resolver class cannot parse the
+   * `target`.
+   * @param target
+   */
+  getDefaultAuthority(target: GrpcUri): string;
+}
+
+const registeredResolvers: { [scheme: string]: ResolverConstructor } = {};
+let defaultScheme: string | null = null;
+
+/**
+ * Register a resolver class to handle target names prefixed with the `prefix`
+ * string. This prefix should correspond to a URI scheme name listed in the
+ * [gRPC Name Resolution document](https://github.com/grpc/grpc/blob/master/doc/naming.md)
+ * @param prefix
+ * @param resolverClass
+ */
+export function registerResolver(
+  scheme: string,
+  resolverClass: ResolverConstructor
+) {
+  registeredResolvers[scheme] = resolverClass;
+}
+
+/**
+ * Register a default resolver to handle target names that do not start with
+ * any registered prefix.
+ * @param resolverClass
+ */
+export function registerDefaultScheme(scheme: string) {
+  defaultScheme = scheme;
+}
+
+/**
+ * Create a name resolver for the specified target, if possible. Throws an
+ * error if no such name resolver can be created.
+ * @param target
+ * @param listener
+ */
+export function createResolver(
+  target: GrpcUri,
+  listener: ResolverListener,
+  options: ChannelOptions
+): Resolver {
+  if (target.scheme !== undefined && target.scheme in registeredResolvers) {
+    return new registeredResolvers[target.scheme](target, listener, options);
+  } else {
+    throw new Error(
+      `No resolver could be created for target ${uriToString(target)}`
+    );
+  }
+}
+
+/**
+ * Get the default authority for the specified target, if possible. Throws an
+ * error if no registered name resolver can parse that target string.
+ * @param target
+ */
+export function getDefaultAuthority(target: GrpcUri): string {
+  if (target.scheme !== undefined && target.scheme in registeredResolvers) {
+    return registeredResolvers[target.scheme].getDefaultAuthority(target);
+  } else {
+    throw new Error(`Invalid target ${uriToString(target)}`);
+  }
+}
+
+export function mapUriDefaultScheme(target: GrpcUri): GrpcUri | null {
+  if (target.scheme === undefined || !(target.scheme in registeredResolvers)) {
+    if (defaultScheme !== null) {
+      return {
+        scheme: defaultScheme,
+        authority: undefined,
+        path: uriToString(target),
+      };
+    } else {
+      return null;
+    }
+  }
+  return target;
+}