ManageEventIndexDialog: Add back a control for the crawler sleep time.

src/indexing/EventIndex.js

@@ -18,6 +18,7 @@ import PlatformPeg from "../PlatformPeg";
 import {MatrixClientPeg} from "../MatrixClientPeg";
 import {EventTimeline, RoomMember} from 'matrix-js-sdk';
 import {sleep} from "../utils/promise";
+import SettingsStore, {SettingLevel} from "../settings/SettingsStore";
 import {EventEmitter} from "events";
 
 /*
@@ -30,7 +31,6 @@ export default class EventIndex extends EventEmitter {
         // The time in ms that the crawler will wait loop iterations if there
         // have not been any checkpoints to consume in the last iteration.
         this._crawlerIdleTime = 5000;
-        this._crawlerSleepTime = 3000;
         // The maximum number of events our crawler should fetch in a single
         // crawl.
         this._eventsPerCrawl = 100;
@@ -299,10 +299,7 @@ export default class EventIndex extends EventEmitter {
         let idle = false;
 
         while (!cancelled) {
-            // This is a low priority task and we don't want to spam our
-            // homeserver with /messages requests so we set a hefty timeout
-            // here.
-            let sleepTime = this._crawlerSleepTime;
+            let sleepTime = SettingsStore.getValueAt(SettingLevel.DEVICE, 'crawlerSleepTime');
 
             // Don't let the user configure a lower sleep time than 100 ms.
             sleepTime = Math.max(sleepTime, 100);