fix: destroy document only on empty connections (#1988)

Co-authored-by: kim <kim.phanhoang@epfl.ch>

Author: pyphilia

src/services/item/plugins/page/WSDoc.test.ts

@@ -0,0 +1,35 @@
+import { WebSocket } from 'ws';
+
+import { MOCK_LOGGER } from '../../../../../test/app';
+import { WSDoc } from './WSDoc';
+
+const conn1 = {
+  on: jest.fn(),
+  close: jest.fn(),
+} as unknown as WebSocket;
+
+const conn2 = {
+  on: jest.fn(),
+  close: jest.fn(),
+} as unknown as WebSocket;
+
+describe('WSDoc', () => {
+  it('closeConn destroy observers when no one is connected to it', () => {
+    const doc = new WSDoc(null as never, 'test', false, MOCK_LOGGER);
+    const initNbObservers = doc._observers.size;
+    expect(initNbObservers).toBeGreaterThan(0);
+
+    doc.addConnection(conn1);
+    doc.addConnection(conn2);
+
+    doc.closeConn(conn1);
+
+    // observers should still exist
+    expect(doc._observers.size).toEqual(initNbObservers);
+
+    doc.closeConn(conn2);
+
+    // observer should be removed
+    expect(doc._observers.size).toEqual(0);
+  });
+});

src/services/item/plugins/page/WSDoc.ts

@@ -149,7 +149,9 @@ export class WSDoc extends Y.Doc {
       const controlledIds: Set<number> = this.conns.get(conn)!;
       this.conns.delete(conn);
       awarenessProtocol.removeAwarenessStates(this.awareness, Array.from(controlledIds), null);
-      this.destroy();
+      if (this.conns.size === 0) {
+        this.destroy();
+      }
     }
     conn.close(code, reason);
   }