From fe4a745109362a6cb8c6e6782c7651135c244dc6 Mon Sep 17 00:00:00 2001
From: Marcus Westin <marcus.westin@gmail.com>
Date: Mon, 13 May 2013 19:26:41 -0700
Subject: [PATCH] Add Pool `connection` event, which fires when the Pool has
 created a new connection. This allows for e.g. setting Session variables on
 the connection before it gets used

---
 Readme.md                                      |  9 +++++++++
 lib/Pool.js                                    |  5 +++++
 test/integration/pool/test-connection-event.js | 15 +++++++++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 test/integration/pool/test-connection-event.js

diff --git a/Readme.md b/Readme.md
index abd5ef727..47951549a 100644
--- a/Readme.md
+++ b/Readme.md
@@ -214,6 +214,15 @@ pool.getConnection(function(err, connection) {
 });
 ```
 
+If you need to set session variables on the connection before it gets used,
+you can listen to the `connection` event.
+
+```js
+pool.on('connection', function(err, connection) {
+  connection.query('SET SESSION auto_increment_increment=1')
+})
+```
+
 When you are done with a connection, just call `connection.end()` and the
 connection will return to the pool, ready to be used again by someone else.
 
diff --git a/lib/Pool.js b/lib/Pool.js
index 9925fdf94..2ae5fe638 100644
--- a/lib/Pool.js
+++ b/lib/Pool.js
@@ -1,9 +1,13 @@
 var mysql        = require('../');
 var Connection   = require('./Connection');
+var EventEmitter = require('events').EventEmitter;
+var Util         = require('util');
 
 module.exports = Pool;
 
+Util.inherits(Pool, EventEmitter);
 function Pool(options) {
+  EventEmitter.call(this);
   this.config = options.config;
   this.config.connectionConfig.pool = this;
 
@@ -39,6 +43,7 @@ Pool.prototype.getConnection = function (cb) {
         return cb(err);
       }
 
+      this.emit('connection', null, connection);
       return cb(null, connection);
     }.bind(this));
   }
diff --git a/test/integration/pool/test-connection-event.js b/test/integration/pool/test-connection-event.js
new file mode 100644
index 000000000..e01d0757c
--- /dev/null
+++ b/test/integration/pool/test-connection-event.js
@@ -0,0 +1,15 @@
+var common     = require('../../common');
+var assert     = require('assert');
+var Connection = require(common.lib + '/Connection');
+var pool       = common.createPool();
+
+var connectionEventHappened = false;
+pool.on('connection', function(err, connection) {
+  connectionEventHappened = true;
+})
+
+pool.getConnection(function(err, connection) {
+  if (err) throw err;
+  assert.equal(connectionEventHappened, true);
+  pool.end();
+});
\ No newline at end of file