refactor: remove duplicate _sockets map

Both the "connected" and the "_sockets" maps were used to track the
Socket instances in the namespace.

Let's merge them into "sockets". It's a breaking change, but:

- the "sockets" object did already exist in Socket.IO v2 (and appears in some examples/tutorials)
- "sockets" makes more sense than "connected" in my opinion
- there was already a breaking change regarding the "connected" property (from object to Map)

Breaking change: the "connected" map is renamed to "sockets"

lib/index.ts

@@ -568,7 +568,7 @@ export class Server extends EventEmitter {
    * @public
    */
   public close(fn?: (err?: Error) => void): void {
-    for (const socket of this.sockets._sockets.values()) {
+    for (const socket of this.sockets.sockets.values()) {
       socket._onclose("server shutting down");
     }
 

lib/namespace.ts

@@ -10,7 +10,7 @@ const debug = debugModule("socket.io:namespace");
 
 export class Namespace extends EventEmitter {
   public readonly name: string;
-  public readonly connected: Map<SocketId, Socket> = new Map();
+  public readonly sockets: Map<SocketId, Socket> = new Map();
 
   public adapter: Adapter;
 
@@ -29,9 +29,6 @@ export class Namespace extends EventEmitter {
   /** @private */
   _ids: number = 0;
 
-  /** @private */
-  _sockets: Map<SocketId, Socket> = new Map();
-
   /**
    * Namespace constructor.
    *
@@ -135,7 +132,7 @@ export class Namespace extends EventEmitter {
           if (err) return socket._error(err.message);
 
           // track socket
-          this._sockets.set(socket.id, socket);
+          this.sockets.set(socket.id, socket);
 
           // it's paramount that the internal `onconnect` logic
           // fires before user-set events to prevent state order
@@ -161,8 +158,8 @@ export class Namespace extends EventEmitter {
    * @private
    */
   _remove(socket: Socket): void {
-    if (this._sockets.has(socket.id)) {
-      this._sockets.delete(socket.id);
+    if (this.sockets.has(socket.id)) {
+      this.sockets.delete(socket.id);
     } else {
       debug("ignoring remove for %s", socket.id);
     }

lib/socket.ts

@@ -291,7 +291,6 @@ export class Socket extends EventEmitter {
    */
   _onconnect(): void {
     debug("socket connected - writing packet");
-    this.nsp.connected.set(this.id, this);
     this.join(this.id);
     this.packet({ type: PacketType.CONNECT, data: { sid: this.id } });
   }
@@ -430,7 +429,6 @@ export class Socket extends EventEmitter {
     this.client._remove(this);
     this.connected = false;
     this.disconnected = true;
-    this.nsp.connected.delete(this.id);
     super.emit("disconnect", reason);
   }
 

package.json

@@ -37,7 +37,7 @@
     "base64id": "~2.0.0",
     "debug": "~4.1.0",
     "engine.io": "~4.0.0",
-    "socket.io-adapter": "~2.0.1",
+    "socket.io-adapter": "2.0.3-rc1",
     "socket.io-client": "3.0.0-rc1",
     "socket.io-parser": "4.0.1-rc2"
   },