Merge pull request #14864 from Automattic/vkarpov15/gh-14859

fix(connection): avoid MaxListenersExceededWarning on multiple useDb() calls by avoiding using event emitters

Author: vkarpov15

Diff for: lib/connection.js

@@ -71,6 +71,9 @@ function Connection(base) {
   } else {
     this.id = base.nextConnectionId;
   }
+
+  // Internal queue of objects `{ fn, ctx, args }` that Mongoose calls when this connection is successfully
+  // opened. In `onOpen()`, Mongoose calls every entry in `_queue` and empties the queue.
   this._queue = [];
 }
 

Diff for: lib/cursor/queryCursor.js

@@ -10,7 +10,7 @@ const eachAsync = require('../helpers/cursor/eachAsync');
 const helpers = require('../queryHelpers');
 const kareem = require('kareem');
 const immediate = require('../helpers/immediate');
-const { once } = require('node:events');
+const { once } = require('events');
 const util = require('util');
 
 /**

Diff for: lib/drivers/node-mongodb-native/connection.js

@@ -96,7 +96,7 @@ NativeConnection.prototype.useDb = function(name, options) {
   if (this.db && this._readyState === STATES.connected) {
     wireup();
   } else {
-    this.once('connected', wireup);
+    this._queue.push({ fn: wireup });
   }
 
   function wireup() {