Load test: emulate Jitsi-Meet's lastN and selectParticipant behavior. (#8926)

resources/load-test/load-test-participant.js

 import { setConfigFromURLParams } from '../../react/features/base/config/functions';
 import { parseURLParams } from '../../react/features/base/util/parseURLParams';
 import { parseURIString } from '../../react/features/base/util/uri';
+import { validateLastNLimits, limitLastN } from '../../react/features/base/lastn/functions';
 
 setConfigFromURLParams(config, {}, {}, window.location);
 
     }
 }
 
+/**
+ * Simple emulation of jitsi-meet's lastN behavior
+ */
+function updateLastN() {
+    let lastN = typeof config.channelLastN === 'undefined' ? -1 : config.channelLastN;
+
+    const limitedLastN = limitLastN(numParticipants, validateLastNLimits(config.lastNLimits));
+
+    if (limitedLastN !== undefined) {
+        lastN = lastN === -1 ? limitedLastN : Math.min(limitedLastN, lastN);
+    }
+
+    if (lastN === room.getLastN()) {
+        return;
+    }
+
+    room.setLastN(lastN);
+}
+
 /**
  *
  */
 function setNumberOfParticipants() {
     $('#participants').text(numParticipants);
+    /* jitsi-meet's current Tile View behavior. */
+    const ids = room.getParticipants().map(participant => participant.id);
+    room.selectParticipants(ids);
     updateMaxFrameHeight();
+    updateLastN();
 }
 
 /**
     }, 2000);
 }
 
+/**
+ *
+ * @param id
+ */
+function onUserJoined(id) {
+    numParticipants++;
+    setNumberOfParticipants();
+    remoteTracks[id] = [];
+}
+
 /**
  *
  * @param id
     room.on(JitsiMeetJS.events.conference.STARTED_MUTED, onStartMuted);
     room.on(JitsiMeetJS.events.conference.TRACK_ADDED, onRemoteTrack);
     room.on(JitsiMeetJS.events.conference.CONFERENCE_JOINED, onConferenceJoined);
-    room.on(JitsiMeetJS.events.conference.USER_JOINED, id => {
-        numParticipants++;
-        setNumberOfParticipants();
-        remoteTracks[id] = [];
-    });
+    room.on(JitsiMeetJS.events.conference.USER_JOINED, onUserJoined);
     room.on(JitsiMeetJS.events.conference.USER_LEFT, onUserLeft);
 
     const devices = [];