From 6febfb1a0e8c9dd669dbba4915c0e581a4e9d040 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Fern=C3=A1ndez=20Haro?=
 <alejandro.haro@elastic.co>
Date: Tue, 6 Oct 2020 12:45:58 +0100
Subject: [PATCH] [Telemetry] Synchronous `setup` and `start` methods (#79457)

# Conflicts:
#	src/plugins/telemetry/server/plugin.ts
---
 src/plugins/telemetry/server/fetcher.ts | 13 +++++-----
 src/plugins/telemetry/server/plugin.ts  | 33 +++++++++++++++++++------
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/src/plugins/telemetry/server/fetcher.ts b/src/plugins/telemetry/server/fetcher.ts
index 75cfac721bcd3..2c5237bc736f7 100644
--- a/src/plugins/telemetry/server/fetcher.ts
+++ b/src/plugins/telemetry/server/fetcher.ts
@@ -18,7 +18,7 @@
  */
 
 import moment from 'moment';
-import { Observable } from 'rxjs';
+import { Observable, Subscription, timer } from 'rxjs';
 import { take } from 'rxjs/operators';
 // @ts-ignore
 import fetch from 'node-fetch';
@@ -58,7 +58,7 @@ export class FetcherTask {
   private readonly config$: Observable<TelemetryConfigType>;
   private readonly currentKibanaVersion: string;
   private readonly logger: Logger;
-  private intervalId?: NodeJS.Timeout;
+  private intervalId?: Subscription;
   private lastReported?: number;
   private isSending = false;
   private internalRepository?: SavedObjectsClientContract;
@@ -79,15 +79,14 @@ export class FetcherTask {
     this.telemetryCollectionManager = telemetryCollectionManager;
     this.elasticsearchClient = elasticsearch.legacy.createClient('telemetry-fetcher');
 
-    setTimeout(() => {
-      this.sendIfDue();
-      this.intervalId = setInterval(() => this.sendIfDue(), this.checkIntervalMs);
-    }, this.initialCheckDelayMs);
+    this.intervalId = timer(this.initialCheckDelayMs, this.checkIntervalMs).subscribe(() =>
+      this.sendIfDue()
+    );
   }
 
   public stop() {
     if (this.intervalId) {
-      clearInterval(this.intervalId);
+      this.intervalId.unsubscribe();
     }
     if (this.elasticsearchClient) {
       this.elasticsearchClient.close();
diff --git a/src/plugins/telemetry/server/plugin.ts b/src/plugins/telemetry/server/plugin.ts
index bd7a2a8c1a8ca..c586b3b784438 100644
--- a/src/plugins/telemetry/server/plugin.ts
+++ b/src/plugins/telemetry/server/plugin.ts
@@ -17,21 +17,22 @@
  * under the License.
  */
 
-import { Observable } from 'rxjs';
+import { AsyncSubject, Observable } from 'rxjs';
 import { UsageCollectionSetup } from 'src/plugins/usage_collection/server';
 import {
   TelemetryCollectionManagerPluginSetup,
   TelemetryCollectionManagerPluginStart,
 } from 'src/plugins/telemetry_collection_manager/server';
+import { take } from 'rxjs/operators';
 import {
   CoreSetup,
   PluginInitializerContext,
   ISavedObjectsRepository,
   CoreStart,
-  IUiSettingsClient,
   SavedObjectsClient,
   Plugin,
   Logger,
+  UiSettingsServiceStart,
 } from '../../../core/server';
 import { registerRoutes } from './routes';
 import { registerCollection } from './telemetry_collection';
@@ -60,8 +61,11 @@ export class TelemetryPlugin implements Plugin {
   private readonly config$: Observable<TelemetryConfigType>;
   private readonly isDev: boolean;
   private readonly fetcherTask: FetcherTask;
+  /**
+   * @private Used to mark the completion of the old UI Settings migration
+   */
+  private readonly oldUiSettingsHandled$ = new AsyncSubject();
   private savedObjectsClient?: ISavedObjectsRepository;
-  private uiSettingsClient?: IUiSettingsClient;
 
   constructor(initializerContext: PluginInitializerContext<TelemetryConfigType>) {
     this.logger = initializerContext.logger.get();
@@ -74,7 +78,7 @@ export class TelemetryPlugin implements Plugin {
     });
   }
 
-  public async setup(
+  public setup(
     { elasticsearch, http, savedObjects }: CoreSetup,
     { usageCollection, telemetryCollectionManager }: TelemetryPluginsSetup
   ) {
@@ -101,15 +105,30 @@ export class TelemetryPlugin implements Plugin {
   public async start(core: CoreStart, { telemetryCollectionManager }: TelemetryPluginsStart) {
     const { savedObjects, uiSettings } = core;
     this.savedObjectsClient = savedObjects.createInternalRepository();
-    const savedObjectsClient = new SavedObjectsClient(this.savedObjectsClient);
-    this.uiSettingsClient = uiSettings.asScopedToClient(savedObjectsClient);
+
+    // Not catching nor awaiting these promises because they should never reject
+    this.handleOldUiSettings(uiSettings);
+    this.startFetcherWhenOldSettingsAreHandled(core, telemetryCollectionManager);
+  }
+
+  private async handleOldUiSettings(uiSettings: UiSettingsServiceStart) {
+    const savedObjectsClient = new SavedObjectsClient(this.savedObjectsClient!);
+    const uiSettingsClient = uiSettings.asScopedToClient(savedObjectsClient);
 
     try {
-      await handleOldSettings(savedObjectsClient, this.uiSettingsClient);
+      await handleOldSettings(savedObjectsClient, uiSettingsClient);
     } catch (error) {
       this.logger.warn('Unable to update legacy telemetry configs.');
     }
+    // Set the mark in the AsyncSubject as complete so all the methods that require this method to be completed before working, can move on
+    this.oldUiSettingsHandled$.complete();
+  }
 
+  private async startFetcherWhenOldSettingsAreHandled(
+    core: CoreStart,
+    telemetryCollectionManager: TelemetryCollectionManagerPluginStart
+  ) {
+    await this.oldUiSettingsHandled$.pipe(take(1)).toPromise(); // Wait for the old settings to be handled
     this.fetcherTask.start(core, { telemetryCollectionManager });
   }