fix(presence): add TTL-based expiration cleanup using Redis keyspace notifications

packages/mesh/README.md

@@ -323,57 +323,42 @@ Mesh provides a built-in presence system that tracks which connections are prese
 
 ### Server configuration
 
-Enable presence tracking for specific rooms using exact names or regex patterns:
+Enable presence tracking for specific rooms using exact names or regex patterns. You can optionally customize the TTL or restrict access with a guard.
 
 ```ts
 // track presence for all rooms matching a pattern
 server.trackPresence(/^room:.*$/);
 
-// track presence for a specific room
-server.trackPresence("lobby");
-
-// guard who can see presence.
-// clients who attempt to subscribe to the presence of this room
-// will be rejected if the guard returns false
-server.trackPresence("admin-room", async (conn, roomName) => {
-  const meta = await server.connectionManager.getMetadata(conn);
-  return meta?.isAdmin === true;
+// track presence for a specific room with a custom TTL
+server.trackPresence("game-room", {
+  ttl: 60_000, // time in ms before presence entry expires if not refreshed
 });
 
-// custom TTL
-server.trackPresence("game-room", { ttl: 60_000 }); // ms
-
-// guard and TTL
-server.trackPresence("vip-room", {
-  ttl: 30_000,
+// restrict visibility to admins
+server.trackPresence("admin-room", {
   guard: async (conn, roomName) => {
     const meta = await server.connectionManager.getMetadata(conn);
-    return meta?.isVIP === true;
+    return meta?.isAdmin === true;
   }
 });
 ```
 
-When presence tracking is enabled for a room, Mesh automatically:
+When presence tracking is enabled:
 
-- Detects and records the connection IDs of clients joining the room.
-- Emits real‐time “join” and “leave” events to subscribed clients.
-- Automatically refreshes each connection’s presence using a configurable TTL as long as the client remains active.
-- Cleans up expired or disconnected entries to maintain an up-to-date presence list.
+- Mesh stores connection IDs in Redis with a TTL
+- As long as a client remains active, the TTL is automatically refreshed
+- When the TTL expires (e.g. due to disconnect or inactivity), Mesh **automatically marks the connection offline** and emits a `leave` event
 
-### Getting presence information (server-side)
-
-```ts
-// get all connections currently present in a room
-const connectionIds = await server.presenceManager.getPresentConnections("lobby");
-```
+> [!INFO]
+> Under the hood, this uses Redis keyspace notifications to detect expiration events and trigger cleanup. This behavior is enabled by default and can be disabled via the `enablePresenceExpirationEvents` server option.
 
 ### Client usage
 
-Subscribe to presence updates for a room:
+Subscribe to presence updates:
 
 ```ts
 const { success, present } = await client.subscribePresence(
-  "lobby",
+  "room:lobby",
   (update) => {
     if (update.type === "join") {
       console.log("User joined:", update.connectionId);
@@ -387,12 +372,38 @@ const { success, present } = await client.subscribePresence(
 console.log("Currently present:", present); // ["conn1", "conn2", ...]
 ```
 
-Unsubscribe when no longer needed:
+You'll receive:
+
+- The current list of `connectionId`s as `present`
+- Real-time `"join"` and `"leave"` events as users come and go (or TTL expires)
+
+Unsubscribe when done:
 
 ```ts
-await client.unsubscribePresence("lobby");
+await client.unsubscribePresence("room:lobby");
 ```
 
+### Getting presence information (server-side)
+
+```ts
+const ids = await server.presenceManager.getPresentConnections("room:lobby");
+// ["abc123", "def456", ...]
+```
+
+### Disabling auto-cleanup (optional)
+
+If for some reason you don't want TTL expirations to trigger `leave` events, you can disable it in your `MeshServer` options:
+
+```ts
+const server = new MeshServer({
+  port: 8080,
+  redisOptions: { host: "localhost", port: 6379 },
+  enablePresenceExpirationEvents: false,
+});
+```
+
+This disables Redis keyspace notifications and requires you to manage stale connections yourself (not recommended).
+
 ### Combining presence with user info
 
 Presence is most useful when combined with connection metadata. For example:
@@ -407,15 +418,14 @@ server.onConnection(async (connection) => {
     avatar: "https://example.com/avatar.png"
   });
 });
+```
 
-// client: subscribe to presence and resolve metadata
+Then on the client:
+
+```ts
 const { success, present } = await client.subscribePresence(
   "lobby",
   async (update) => {
-    // fetch metadata for the connection that joined/left.
-    //
-    // since clients cannot access `getAllMetadataForRoom()` directly (it's just a server API),
-    // you can expose it via a custom command like `get-user-metadata`:
     const metadata = await client.command("get-user-metadata", {
       connectionId: update.connectionId
     });
@@ -427,16 +437,21 @@ const { success, present } = await client.subscribePresence(
     }
   }
 );
-
-// initial presence - fetch metadata for all present connections
-const allMetadata = await Promise.all(
-  present.map(connectionId =>
-    client.command("get-user-metadata", { connectionId })
-  )
-);
-console.log("Users in lobby:", allMetadata);
 ```
 
+To resolve all present users:
+
+```ts
+const allMetadata = await Promise.all(
+  present.map((connectionId) => client.command("get-user-metadata", { connectionId }))
+);
+
+// [{ userId: "user123", username: "Alice", avatar: "..." }, ...]
+```
+
+> [!TIP]
+> You can expose a `get-user-metadata` command on the server that reads from `connectionManager.getMetadata(...)` to support this.
+
 ### Metadata
 
 You can associate data like user IDs, tokens, or custom attributes with a connection using the `setMetadata` method. This metadata is stored in Redis, making it ideal for identifying users, managing permissions, or persisting session-related data across a distributed setup. Since it lives in Redis, it’s accessible from any server instance.

packages/mesh/src/server/managers/presence.ts

@@ -1,12 +1,22 @@
 import type { Redis } from "ioredis";
 import type { Connection } from "../connection";
 import type { RoomManager } from "./room";
+import type { RedisManager } from "./redis";
 
 type ChannelPattern = string | RegExp;
 
 export class PresenceManager {
   private redis: Redis;
   private roomManager: RoomManager;
+  private redisManager: RedisManager;
+  private presenceExpirationEventsEnabled: boolean;
+
+  private getExpiredEventsPattern(): string {
+    const dbIndex = (this.redis as any).options?.db ?? 0;
+    return `__keyevent@${dbIndex}__:expired`;
+  }
+
+  private readonly PRESENCE_KEY_PATTERN = /^mesh:presence:room:(.+):conn:(.+)$/;
   private trackedRooms: ChannelPattern[] = [];
   private roomGuards: Map<
     ChannelPattern,
@@ -15,9 +25,51 @@ export class PresenceManager {
   private roomTTLs: Map<ChannelPattern, number> = new Map();
   private defaultTTL = 30_000; // 30 seconds default TTL
 
-  constructor(redis: Redis, roomManager: RoomManager) {
+  constructor(
+    redis: Redis,
+    roomManager: RoomManager,
+    redisManager: RedisManager,
+    enableExpirationEvents: boolean = true
+  ) {
     this.redis = redis;
     this.roomManager = roomManager;
+    this.redisManager = redisManager;
+    this.presenceExpirationEventsEnabled = enableExpirationEvents;
+    
+    if (this.presenceExpirationEventsEnabled) {
+      this.subscribeToExpirationEvents();
+    }
+  }
+
+  /**
+   * Subscribes to Redis keyspace notifications for expired presence keys
+   */
+  private subscribeToExpirationEvents(): void {
+    const { subClient } = this.redisManager;
+    const pattern = this.getExpiredEventsPattern();
+    subClient.psubscribe(pattern);
+    
+    subClient.on("pmessage", (pattern, channel, key) => {
+      if (this.PRESENCE_KEY_PATTERN.test(key)) {
+        this.handleExpiredKey(key);
+      }
+    });
+  }
+
+  /**
+   * Handles an expired key notification
+   */
+  private async handleExpiredKey(key: string): Promise<void> {
+    try {
+      const match = key.match(this.PRESENCE_KEY_PATTERN);
+      if (match && match[1] && match[2]) {
+        const roomName = match[1];
+        const connectionId = match[2];
+        await this.markOffline(connectionId, roomName);
+      }
+    } catch (err) {
+      console.error("[PresenceManager] Failed to handle expired key:", err);
+    }
   }
 
   trackRoom(
@@ -113,7 +165,8 @@ export class PresenceManager {
 
     const pipeline = this.redis.pipeline();
     pipeline.sadd(roomKey, connectionId);
-    pipeline.set(connKey, "", "EX", Math.floor(ttl / 1000));
+    const ttlSeconds = Math.max(1, Math.floor(ttl / 1000));
+    pipeline.set(connKey, "", "EX", ttlSeconds);
     await pipeline.exec();
 
     await this.publishPresenceUpdate(roomName, connectionId, "join");
@@ -134,8 +187,8 @@ export class PresenceManager {
   async refreshPresence(connectionId: string, roomName: string): Promise<void> {
     const connKey = this.presenceConnectionKey(roomName, connectionId);
     const ttl = this.getRoomTTL(roomName);
-
-    await this.redis.set(connKey, "", "EX", Math.floor(ttl / 1000));
+    const ttlSeconds = Math.max(1, Math.floor(ttl / 1000));
+    await this.redis.set(connKey, "", "EX", ttlSeconds);
   }
 
   async getPresentConnections(roomName: string): Promise<string[]> {

packages/mesh/src/server/managers/redis.ts

@@ -117,4 +117,26 @@ export class RedisManager {
   set isShuttingDown(value: boolean) {
     this._isShuttingDown = value;
   }
+
+  /**
+   * Enables Redis keyspace notifications for expired events by updating the
+   * "notify-keyspace-events" configuration. Ensures that both keyevent ('E')
+   * and expired event ('x') notifications are enabled. If they are not already
+   * present, the method appends them to the current configuration.
+   *
+   * @returns {Promise<void>} A promise that resolves when the configuration has been updated.
+   * @throws {Error} If the Redis CONFIG commands fail or the connection encounters an error.
+   */
+  async enableKeyspaceNotifications(): Promise<void> {
+    const result = await this.redis.config("GET", "notify-keyspace-events");
+    const currentConfig =
+      Array.isArray(result) && result.length > 1 ? result[1] : "";
+
+    // add expired events notification if not already enabled
+    // 'E' enables keyevent notifications, 'x' enables expired events
+    let newConfig = currentConfig || "";
+    if (!newConfig.includes("E")) newConfig += "E";
+    if (!newConfig.includes("x")) newConfig += "x";
+    await this.redis.config("SET", "notify-keyspace-events", newConfig);
+  }
 }

packages/mesh/src/server/mesh-server.ts

@@ -74,8 +74,14 @@ export class MeshServer extends WebSocketServer {
     );
     this.presenceManager = new PresenceManager(
       this.redisManager.redis,
-      this.roomManager
+      this.roomManager,
+      this.redisManager,
+      this.serverOptions.enablePresenceExpirationEvents
     );
+    if (this.serverOptions.enablePresenceExpirationEvents) {
+      this.redisManager.enableKeyspaceNotifications()
+        .catch(err => this.emit("error", new Error(`Failed to enable keyspace notifications: ${err}`)));
+    }
     this.commandManager = new CommandManager((err) => this.emit("error", err));
     this.channelManager = new ChannelManager(
       this.redisManager.redis,

packages/mesh/src/server/types.ts

@@ -37,6 +37,14 @@ export type MeshServerOptions = ServerOptions & {
   latencyInterval?: number;
   redisOptions: RedisOptions;
 
+  /**
+   * Whether to enable Redis keyspace notifications for presence expiration.
+   * When enabled, connections will be automatically marked as offline when their presence TTL expires.
+   *
+   * @default true
+   */
+  enablePresenceExpirationEvents?: boolean;
+
   /**
    * The maximum number of consecutive ping intervals the server will wait
    * for a pong response before considering the client disconnected.

packages/mesh/src/tests/presence-subscription.test.ts

@@ -17,6 +17,7 @@ const createTestServer = (port: number) =>
     },
     pingInterval: 1000,
     latencyInterval: 500,
+    enablePresenceExpirationEvents: true,
   });
 
 const flushRedis = async () => {
@@ -243,6 +244,39 @@ describe("Presence Subscription", () => {
     present = await server.presenceManager.getPresentConnections(roomName);
     expect(present).not.toContain(connection2.id);
   });
+
+  test("presence is automatically cleaned up when TTL expires", async () => {
+    const roomName = "test:room:auto-cleanup";
+    const shortTTL = 1000;
+
+    const testServer = createTestServer(port + 100);
+    await testServer.ready();
+
+    testServer.trackPresence(roomName, { ttl: shortTTL });
+
+    const testClient = new MeshClient(`ws://localhost:${port + 100}`);
+    await testClient.connect();
+
+    const connections = testServer.connectionManager.getLocalConnections();
+    const connection = connections[0]!;
+
+    await testServer.addToRoom(roomName, connection);
+
+    let present = await testServer.presenceManager.getPresentConnections(
+      roomName
+    );
+    expect(present).toContain(connection.id);
+
+    // wait for more than the TTL to allow the key to expire and notification to be processed
+    await wait(shortTTL * 3);
+
+    // the connection should be automatically marked as offline when the key expires
+    present = await testServer.presenceManager.getPresentConnections(roomName);
+    expect(present).not.toContain(connection.id);
+
+    await testClient.close();
+    await testServer.close();
+  }, 10000);
 });
 
 describe("Presence Subscription (Multiple Instances)", () => {