EventIndex: Use a setting for the crawler sleep time.

src/indexing/EventIndex.js

@@ -16,6 +16,8 @@ limitations under the License.
 
 import PlatformPeg from "../PlatformPeg";
 import {MatrixClientPeg} from "../MatrixClientPeg";
+import SettingsStore from '../settings/SettingsStore';
+import {SettingLevel} from "../settings/SettingsStore";
 import {sleep} from "../utils/promise";
 
 /*
@@ -24,9 +26,9 @@ import {sleep} from "../utils/promise";
 export default class EventIndex {
     constructor() {
         this.crawlerCheckpoints = [];
-        // The time that the crawler will wait between /rooms/{room_id}/messages
-        // requests
-        this._crawlerTimeout = 3000;
+        // 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;
         // The maximum number of events our crawler should fetch in a single
         // crawl.
         this._eventsPerCrawl = 100;
@@ -194,11 +196,22 @@ export default class EventIndex {
             cancelled = true;
         };
 
+        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.
-            await sleep(this._crawlerTimeout);
+            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);
+
+            if (idle) {
+                sleepTime = this._crawlerIdleTime;
+            }
+
+            await sleep(sleepTime);
 
             console.log("EventIndex: Running the crawler loop.");
 
@@ -211,9 +224,12 @@ export default class EventIndex {
             /// There is no checkpoint available currently, one may appear if
             // a sync with limited room timelines happens, so go back to sleep.
             if (checkpoint === undefined) {
+                idle = true;
                 continue;
             }
 
+            idle = false;
+
             console.log("EventIndex: crawling using checkpoint", checkpoint);
 
             // We have a checkpoint, let us fetch some messages, again, very

src/settings/Settings.js

@@ -486,4 +486,9 @@ export const SETTINGS = {
         supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         default: RIGHT_PANEL_PHASES.GroupMemberList,
     },
+    "crawlerSleepTime": {
+        supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
+        displayName: _td("How long should the crawler wait between requests"),
+        default: 3000,
+    }
 };