revert: fix: cleanup pending acks on timeout to prevent memory leak

This reverts commit da04267ffc.

The reverted fix was incorrect because the rooms might have changed between the emit() and the timeout.

packages/socket.io-adapter/lib/cluster-adapter.ts

@@ -508,7 +508,7 @@ export abstract class ClusterAdapter extends Adapter {
       }, opts.flags!.timeout);
     }
 
-    return super.broadcastWithAck(packet, opts, clientCountCallback, ack);
+    super.broadcastWithAck(packet, opts, clientCountCallback, ack);
   }
 
   override async addSockets(opts: BroadcastOptions, rooms: Room[]) {

packages/socket.io-adapter/lib/in-memory-adapter.ts

@@ -229,14 +229,6 @@ export class Adapter extends EventEmitter {
     });
 
     clientCountCallback(clientCount);
-
-    return {
-      cleanup: () => {
-        this.apply(opts, (socket) => {
-          socket.acks.delete(packet.id);
-        });
-      },
-    };
   }
 
   private _encode(packet: unknown, packetOpts: Record<string, unknown>) {

packages/socket.io/lib/broadcast-operator.ts

@@ -232,11 +232,9 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
     const ack = data.pop() as (...args: any[]) => void;
     let timedOut = false;
     let responses: any[] = [];
-    let cleanupPendingAcks: (() => void) | undefined;
 
     const timer = setTimeout(() => {
       timedOut = true;
-      cleanupPendingAcks?.();
       ack.apply(this, [
         new Error("operation has timed out"),
         this.flags.expectSingleResponse ? null : responses,
@@ -261,7 +259,7 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
       }
     };
 
-    const result = this.adapter.broadcastWithAck(
+    this.adapter.broadcastWithAck(
       packet,
       {
         rooms: this.rooms,
@@ -281,10 +279,6 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
       },
     );
 
-    if (result && typeof result.cleanup === "function") {
-      cleanupPendingAcks = result.cleanup;
-    }
-
     this.adapter.serverCount().then((serverCount) => {
       expectedServerCount = serverCount;
       checkCompleteness();

packages/socket.io/test/messaging-many.ts

@@ -534,11 +534,6 @@ describe("messaging many", () => {
         // @ts-ignore
         expect(err.responses).to.contain(1, 2);
 
-        for (const [, serverSocket] of io.of("/").sockets) {
-          // @ts-ignore accessing private acks map to verify cleanup
-          expect(serverSocket.acks.size).to.be(0);
-        }
-
         success(done, io, socket1, socket2, socket3);
       }
     });