fix(buffer): live counter

apps/api/src/controllers/live.controller.ts

@@ -6,8 +6,8 @@ import { getSuperJson } from '@openpanel/common';
 import type { IServiceEvent, Notification } from '@openpanel/db';
 import {
   TABLE_NAMES,
+  eventBuffer,
   getEvents,
-  getLiveVisitors,
   getProfileByIdCached,
   transformMinimalEvent,
 } from '@openpanel/db';
@@ -82,20 +82,20 @@ export function wsVisitors(
     if (channel === 'event:received') {
       const event = getSuperJson<IServiceEvent>(message);
       if (event?.projectId === params.projectId) {
-        getLiveVisitors(params.projectId).then((count) => {
+        eventBuffer.getActiveVisitorCount(params.projectId).then((count) => {
           connection.socket.send(String(count));
         });
       }
     }
   };
   const pmessage = (pattern: string, channel: string, message: string) => {
-    if (!message.startsWith('live:visitors:')) {
+    if (!message.startsWith('live:visitor:')) {
       return null;
     }
 
     const [projectId] = getLiveEventInfo(message);
     if (projectId && projectId === params.projectId) {
-      getLiveVisitors(params.projectId).then((count) => {
+      eventBuffer.getActiveVisitorCount(params.projectId).then((count) => {
         connection.socket.send(String(count));
       });
     }

apps/dashboard/src/components/overview/live-counter/index.tsx

@@ -1,12 +1,12 @@
 import withSuspense from '@/hocs/with-suspense';
 
-import { getLiveVisitors } from '@openpanel/db';
+import { eventBuffer } from '@openpanel/db';
 
 import type { LiveCounterProps } from './live-counter';
 import LiveCounter from './live-counter';
 
 async function ServerLiveCounter(props: Omit<LiveCounterProps, 'data'>) {
-  const count = await getLiveVisitors(props.projectId);
+  const count = await eventBuffer.getActiveVisitorCount(props.projectId);
   return <LiveCounter data={count} {...props} />;
 }
 

apps/dashboard/src/hooks/useWS.ts

@@ -39,7 +39,7 @@ export default function useWS<T>(
     onMessage(event) {
       try {
         const data = getSuperJson<T>(event.data);
-        if (data) {
+        if (data !== null && data !== undefined) {
           debouncedOnMessage(data);
         }
       } catch (error) {

packages/db/src/buffers/event-buffer-redis.ts

@@ -54,6 +54,8 @@ export class EventBuffer extends BaseBuffer {
       )
     : 1000;
 
+  private activeVisitorsExpiration = 60 * 5; // 5 minutes
+
   private sessionEvents = ['screen_view', 'session_end'];
 
   // LIST - Stores events without sessions
@@ -246,8 +248,11 @@ return "OK"
       }
 
       if (event.profile_id) {
-        multi.sadd(`live:visitors:${event.project_id}`, event.profile_id);
+        this.incrementActiveVisitorCount(
-        multi.expire(`live:visitors:${event.project_id}`, 60 * 5); // 5 minutes
+          multi,
+          event.project_id,
+          event.profile_id,
+        );
       }
 
       if (!_multi) {
@@ -689,4 +694,44 @@ return "OK"
     );
     return count;
   }
+
+  private async incrementActiveVisitorCount(
+    multi: ReturnType<Redis['multi']>,
+    projectId: string,
+    profileId: string,
+  ) {
+    // Add/update visitor with current timestamp as score
+    const now = Date.now();
+    const zsetKey = `live:visitors:${projectId}`;
+    return (
+      multi
+        // To keep the count
+        .zadd(zsetKey, now, profileId)
+        // To trigger the expiration listener
+        .set(
+          `live:visitor:${projectId}:${profileId}`,
+          '1',
+          'EX',
+          this.activeVisitorsExpiration,
+        )
+    );
+  }
+
+  public async getActiveVisitorCount(projectId: string): Promise<number> {
+    const redis = getRedisCache();
+    const zsetKey = `live:visitors:${projectId}`;
+    const cutoff = Date.now() - this.activeVisitorsExpiration * 1000;
+
+    const multi = redis.multi();
+    multi
+      .zremrangebyscore(zsetKey, '-inf', cutoff)
+      .zcount(zsetKey, cutoff, '+inf');
+
+    const [, count] = (await multi.exec()) as [
+      [Error | null, any],
+      [Error | null, number],
+    ];
+
+    return count[1] || 0;
+  }
 }

packages/db/src/buffers/index.ts

@@ -1,8 +1,5 @@
-import { BotBuffer as BotBufferPsql } from './bot-buffer-psql';
 import { BotBuffer as BotBufferRedis } from './bot-buffer-redis';
-import { EventBuffer as EventBufferPsql } from './event-buffer-psql';
 import { EventBuffer as EventBufferRedis } from './event-buffer-redis';
-import { ProfileBuffer as ProfileBufferPsql } from './profile-buffer-psql';
 import { ProfileBuffer as ProfileBufferRedis } from './profile-buffer-redis';
 
 export const eventBuffer = new EventBufferRedis();

packages/db/src/services/event.service.ts

@@ -1,9 +1,9 @@
-import { mergeDeepRight, omit, uniq } from 'ramda';
+import { mergeDeepRight, uniq } from 'ramda';
 import { escape } from 'sqlstring';
 import { v4 as uuid } from 'uuid';
 
 import { toDots } from '@openpanel/common';
-import { cacheable, getRedisCache } from '@openpanel/redis';
+import { cacheable } from '@openpanel/redis';
 import type { IChartEventFilter } from '@openpanel/validation';
 
 import { botBuffer, eventBuffer } from '../buffers';
@@ -234,10 +234,6 @@ export function transformMinimalEvent(
   };
 }
 
-export async function getLiveVisitors(projectId: string) {
-  return getRedisCache().scard(`live:visitors:${projectId}`);
-}
-
 export async function getEvents(
   sql: string,
   options: GetEventsOptions = {},