Enhancement: expose ping() on pingable-connections.

This PR introduces a new PingableConnection interface and exposes
a ping method on \Doctrine\DBAL\Connection. For drivers where no
ping is supported, a \Doctrine\DBAL\ConnectionException is thrown.

lib/Doctrine/DBAL/Connection.php

@@ -30,6 +30,7 @@ use Doctrine\DBAL\Cache\ResultCacheStatement;
 use Doctrine\DBAL\Cache\QueryCacheProfile;
 use Doctrine\DBAL\Cache\ArrayStatement;
 use Doctrine\DBAL\Cache\CacheException;
+use Doctrine\DBAL\Driver\PingableConnection;
 
 /**
  * A wrapper around a Doctrine\DBAL\Driver\Connection that adds features like
@@ -1488,4 +1489,17 @@ class Connection implements DriverConnection
     {
         return new Query\QueryBuilder($this);
     }
+
+    /**
+     * Ping the server!
+     *
+     * @return bool
+     */
+    public function ping()
+    {
+        if (!($this->_conn instanceof PingableConnection)) {
+            throw ConnectionException::unsupportedFeature('ping');
+        }
+        return $this->_conn->ping();
+    }
 }

lib/Doctrine/DBAL/ConnectionException.php

@@ -57,4 +57,12 @@ class ConnectionException extends DBALException
     {
         return new self("May not alter the nested transaction with savepoints behavior while a transaction is open.");
     }
+
+    /**
+     * @return \Doctrine\DBAL\ConnectionException
+     */
+    public static function unsupportedFeature($feature)
+    {
+        return new self(sprintf("The '%' feature is not supported by this connection/driver.", $feature));
+    }
 }

lib/Doctrine/DBAL/Driver/Mysqli/MysqliConnection.php

@@ -20,11 +20,12 @@
 namespace Doctrine\DBAL\Driver\Mysqli;
 
 use Doctrine\DBAL\Driver\Connection as Connection;
+use \Doctrine\DBAL\Driver\PingableConnection;
 
 /**
  * @author Kim Hemsø Rasmussen <kimhemsoe@gmail.com>
  */
-class MysqliConnection implements Connection
+class MysqliConnection implements Connection, PingableConnection
 {
     /**
      * @var \mysqli
@@ -207,4 +208,14 @@ class MysqliConnection implements Connection
             );
         }
     }
+
+    /**
+     * Pings the server and re-connects when `mysqli.reconnect = 1`
+     *
+     * @return bool
+     */
+    public function ping()
+    {
+        return $this->_conn->ping();
+    }
 }

lib/Doctrine/DBAL/Driver/PingableConnection.php

+<?php
+namespace Doctrine\DBAL\Driver;
+
+interface PingableConnection
+{
+    public function ping();
+}
\ No newline at end of file

tests/Doctrine/Tests/DBAL/Functional/Mysqli/ConnectionTest.php

@@ -39,6 +39,12 @@ class ConnectionTest extends \Doctrine\Tests\DbalFunctionalTestCase
         $this->getConnection(array('hello' => 'world')); // use local infile
     }
 
+    public function testPing()
+    {
+        $conn = $this->getConnection(array());
+        $conn->ping();
+    }
+
     private function getConnection(array $driverOptions)
     {
         return new \Doctrine\DBAL\Driver\Mysqli\MysqliConnection(