Emit queue event

Readme.md

@@ -190,9 +190,9 @@ fails assumed to be plaintext strings.
 The `ssl` option in the connection options takes a string or an object. When given a string,
 it uses one of the predefined SSL profiles included. The following profiles are included:
 
-* `"Amazon RDS"`: this profile is for connecting to an Amazon RDS server and contains the
-  ca from https://rds.amazonaws.com/doc/rds-ssl-ca-cert.pem
-
+* `"Amazon RDS"`: this profile is for connecting to an Amazon RDS server and contains the
+  ca from https://rds.amazonaws.com/doc/rds-ssl-ca-cert.pem
+
 When connecting to other servers, you will need to provide an object of options, in the
 same format as [crypto.createCredentials](http://nodejs.org/api/crypto.html#crypto_crypto_createcredentials_details).
 Please note the arguments expect a string of the certificate, not a file name to the
@@ -319,6 +319,23 @@ up to 100 connections, but only ever use 5 simultaneously, only 5 connections
 will be made. Connections are also cycled round-robin style, with connections
 being taken from the top of the pool and returning to the bottom.
 
+Once the number of active connections reaches `connectionLimit` (see blelow)
+the connection will be queued and the pool will emit a `queue` event with
+the number of queued connections as the first argument to the callback.
+
+```js
+var mysql = require('mysql');
+var pool  = mysql.createPool(...);
+
+pool.on('queue',function(queuedConnections) {
+	// Do something i.e. log to console
+	console.error('connectionLimit reached, '+queuedConnections+' connections in the queue');
+});
+
+// Create and use more than connectionLimit connections
+
+```
+
 When a previous connection is retrieved from the pool, a ping packet is sent
 to the server to check if the connection is still good.
 

lib/Pool.js

@@ -62,9 +62,11 @@ Pool.prototype.getConnection = function (cb) {
     return cb(new Error('Queue limit reached.'));
   }
 
-  if (cb && process.domain)
+  if (cb && process.domain) {
     cb = process.domain.bind(cb);
+  }
   this._connectionQueue.push(cb);
+  this.emit('queue',this._connectionQueue.length);
 };
 
 Pool.prototype.acquireConnection = function acquireConnection(connection, cb) {