[PM-8748] Ensure Reasonable ConfigService Emission (#10452)

* Add Slow Emission Guard

* Remove Jest Timer Call

* Do Slow Emission Guard For All Environments

* Update Comment

libs/common/src/platform/services/config/config.service.spec.ts

@@ -3,8 +3,8 @@
  * @jest-environment ../../libs/shared/test.environment.ts
  */
 
-import { mock } from "jest-mock-extended";
-import { Subject, firstValueFrom, of } from "rxjs";
+import { matches, mock } from "jest-mock-extended";
+import { BehaviorSubject, Subject, bufferCount, firstValueFrom, of } from "rxjs";
 
 import {
   FakeGlobalState,
@@ -35,6 +35,7 @@ import {
   RETRIEVAL_INTERVAL,
   GLOBAL_SERVER_CONFIGURATIONS,
   USER_SERVER_CONFIG,
+  SLOW_EMISSION_GUARD,
 } from "./default-config.service";
 
 describe("ConfigService", () => {
@@ -65,12 +66,14 @@ describe("ConfigService", () => {
   describe.each([null, userId])("active user: %s", (activeUserId) => {
     let sut: DefaultConfigService;
 
+    const environmentSubject = new BehaviorSubject(environmentFactory(activeApiUrl));
+
     beforeAll(async () => {
       await accountService.switchAccount(activeUserId);
     });
 
     beforeEach(() => {
-      environmentService.environment$ = of(environmentFactory(activeApiUrl));
+      environmentService.environment$ = environmentSubject;
       sut = new DefaultConfigService(
         configApiService,
         environmentService,
@@ -129,7 +132,8 @@ describe("ConfigService", () => {
             await firstValueFrom(sut.serverConfig$);
 
             expect(logService.error).toHaveBeenCalledWith(
-              `Unable to fetch ServerConfig from ${activeApiUrl}: Unable to fetch`,
+              `Unable to fetch ServerConfig from ${activeApiUrl}`,
+              matches<Error>((e) => e.message === "Unable to fetch"),
             );
           });
         });
@@ -138,6 +142,10 @@ describe("ConfigService", () => {
           const response = serverConfigResponseFactory();
           const newConfig = new ServerConfig(new ServerConfigData(response));
 
+          beforeEach(() => {
+            configApiService.get.mockResolvedValue(response);
+          });
+
           it("should be a new config", async () => {
             expect(newConfig).not.toEqual(activeUserId ? userStored : globalStored[activeApiUrl]);
           });
@@ -149,8 +157,6 @@ describe("ConfigService", () => {
           });
 
           it("returns the updated config", async () => {
-            configApiService.get.mockResolvedValue(response);
-
             const actual = await firstValueFrom(sut.serverConfig$);
 
             // This is the time the response is converted to a config
@@ -270,6 +276,51 @@ describe("ConfigService", () => {
       });
     });
   });
+
+  describe("slow configuration", () => {
+    const environmentSubject = new BehaviorSubject<Environment>(null);
+
+    let sut: DefaultConfigService = null;
+
+    beforeEach(async () => {
+      const config = serverConfigFactory("existing-data", tooOld);
+      environmentService.environment$ = environmentSubject;
+
+      globalState.stateSubject.next({ [apiUrl(0)]: config });
+      userState.stateSubject.next([userId, config]);
+
+      configApiService.get.mockImplementation(() => {
+        return new Promise<ServerConfigResponse>((resolve) => {
+          setTimeout(() => {
+            resolve(serverConfigResponseFactory("slow-response"));
+          }, SLOW_EMISSION_GUARD + 20);
+        });
+      });
+
+      sut = new DefaultConfigService(
+        configApiService,
+        environmentService,
+        logService,
+        stateProvider,
+        authService,
+      );
+    });
+
+    afterEach(() => {
+      jest.resetAllMocks();
+    });
+
+    it("emits old configuration when the http call takes a long time", async () => {
+      environmentSubject.next(environmentFactory(apiUrl(0)));
+
+      const configs = await firstValueFrom(sut.serverConfig$.pipe(bufferCount(2)));
+
+      await jest.runOnlyPendingTimersAsync();
+
+      expect(configs[0].gitHash).toBe("existing-data");
+      expect(configs[1].gitHash).toBe("slow-response");
+    });
+  });
 });
 
 function apiUrl(count: number) {
@@ -305,8 +356,9 @@ function serverConfigResponseFactory(hash?: string) {
   });
 }
 
-function environmentFactory(apiUrl: string) {
+function environmentFactory(apiUrl: string, isCloud: boolean = true) {
   return {
     getApiUrl: () => apiUrl,
+    isCloud: () => isCloud,
   } as Environment;
 }

libs/common/src/platform/services/config/default-config.service.ts

@@ -24,7 +24,7 @@ import { UserId } from "../../../types/guid";
 import { ConfigApiServiceAbstraction } from "../../abstractions/config/config-api.service.abstraction";
 import { ConfigService } from "../../abstractions/config/config.service";
 import { ServerConfig } from "../../abstractions/config/server-config";
-import { EnvironmentService, Region } from "../../abstractions/environment.service";
+import { Environment, EnvironmentService, Region } from "../../abstractions/environment.service";
 import { LogService } from "../../abstractions/log.service";
 import { devFlagEnabled, devFlagValue } from "../../misc/flags";
 import { ServerConfigData } from "../../models/data/server-config.data";
@@ -34,6 +34,8 @@ export const RETRIEVAL_INTERVAL = devFlagEnabled("configRetrievalIntervalMs")
   ? (devFlagValue("configRetrievalIntervalMs") as number)
   : 3_600_000; // 1 hour
 
+export const SLOW_EMISSION_GUARD = 800;
+
 export type ApiUrl = string;
 
 export const USER_SERVER_CONFIG = new UserKeyDefinition<ServerConfig>(CONFIG_DISK, "serverConfig", {
@@ -64,29 +66,32 @@ export class DefaultConfigService implements ConfigService {
     private stateProvider: StateProvider,
     private authService: AuthService,
   ) {
-    const apiUrl$ = this.environmentService.environment$.pipe(
-      map((environment) => environment.getApiUrl()),
-    );
     const userId$ = this.stateProvider.activeUserId$;
     const authStatus$ = userId$.pipe(
       switchMap((userId) => (userId == null ? of(null) : this.authService.authStatusFor$(userId))),
     );
 
-    this.serverConfig$ = combineLatest([userId$, apiUrl$, authStatus$]).pipe(
-      switchMap(([userId, apiUrl, authStatus]) => {
+    this.serverConfig$ = combineLatest([
+      userId$,
+      this.environmentService.environment$,
+      authStatus$,
+    ]).pipe(
+      switchMap(([userId, environment, authStatus]) => {
         if (userId == null || authStatus !== AuthenticationStatus.Unlocked) {
-          return this.globalConfigFor$(apiUrl).pipe(
-            map((config) => [config, null, apiUrl] as const),
+          return this.globalConfigFor$(environment.getApiUrl()).pipe(
+            map((config) => [config, null, environment] as const),
           );
         }
 
-        return this.userConfigFor$(userId).pipe(map((config) => [config, userId, apiUrl] as const));
+        return this.userConfigFor$(userId).pipe(
+          map((config) => [config, userId, environment] as const),
+        );
       }),
       tap(async (rec) => {
-        const [existingConfig, userId, apiUrl] = rec;
+        const [existingConfig, userId, environment] = rec;
         // Grab new config if older retrieval interval
         if (!existingConfig || this.olderThanRetrievalInterval(existingConfig.utcDate)) {
-          await this.renewConfig(existingConfig, userId, apiUrl);
+          await this.renewConfig(existingConfig, userId, environment);
         }
       }),
       switchMap(([existingConfig]) => {
@@ -149,10 +154,20 @@ export class DefaultConfigService implements ConfigService {
   private async renewConfig(
     existingConfig: ServerConfig,
     userId: UserId,
-    apiUrl: string,
+    environment: Environment,
   ): Promise<void> {
     try {
+      // Feature flags often have a big impact on user experience, lets ensure we return some value
+      // somewhat quickly even though it may not be accurate, we won't cancel the HTTP request
+      // though so that hopefully it can have finished and hydrated a more accurate value.
+      const handle = setTimeout(() => {
+        this.logService.info(
+          "Self-host environment did not respond in time, emitting previous config.",
+        );
+        this.failedFetchFallbackSubject.next(existingConfig);
+      }, SLOW_EMISSION_GUARD);
       const response = await this.configApiService.get(userId);
+      clearTimeout(handle);
       const newConfig = new ServerConfig(new ServerConfigData(response));
 
       // Update the environment region
@@ -167,7 +182,7 @@ export class DefaultConfigService implements ConfigService {
       if (userId == null) {
         // update global state with new pulled config
         await this.stateProvider.getGlobal(GLOBAL_SERVER_CONFIGURATIONS).update((configs) => {
-          return { ...configs, [apiUrl]: newConfig };
+          return { ...configs, [environment.getApiUrl()]: newConfig };
         });
       } else {
         // update state with new pulled config
@@ -175,9 +190,7 @@ export class DefaultConfigService implements ConfigService {
       }
     } catch (e) {
       // mutate error to be handled by catchError
-      this.logService.error(
-        `Unable to fetch ServerConfig from ${apiUrl}: ${(e as Error)?.message}`,
-      );
+      this.logService.error(`Unable to fetch ServerConfig from ${environment.getApiUrl()}`, e);
       // Emit the existing config
       this.failedFetchFallbackSubject.next(existingConfig);
     }