Too many connection when extending Phalcon\Db\Adapter\Pdo\Mysql

Question

I've attempted to extend the Phalcon\\Db\\Adapter\\Pdo\\Mysql to create a log every time a query function returns false .

Even though I'm not creating any new connections except the one in parent::__construct I'm getting the following exception:

Fatal error: Uncaught PDOException: SQLSTATE[08004] [1040] Too many connections in ...Internal/Database/Mysql.php:14 Stack trace: #0 [internal function]: PDO->__construct('mysql:adapter=M...', '...', '...', Array) #1 [internal function]: Phalcon\Db\Adapter\Pdo->connect(Array) #2  .../Internal/Database/Mysql.php(14): Phalcon\Db\Adapter\Pdo->__construct(Array) #3 .../apps/bootstrap/app.php(378): Internal\Database\Mysql->__construct(Array) #4 [internal function]: Closure->{closure}() #5 [internal function]: Phalcon\Di\Service->resolve(NULL, Object(Phalcon\Di\FactoryDefault)) #6 .../apps/bootstrap/core_services.php(7): Phalcon\Di->get('logs') #7 [internal function]: Closure->{closure}() #8 [internal function]: Phalcon\Di\Service->resolve(NULL, Object(Phalcon\Di\FactoryDefault)) #9 .../apps/libs/Internal/Database/Mysql.php(15): Phalcon\Di->get('logger') #10 .../apps/bootstrap/app.php(37 in .../apps/libs/Internal/Database/Mysql.php on line 14

Code:

namespace Internal\Database;

use Phalcon\Db\Adapter\Pdo\Mysql as PhalconMysql;
use Phalcon\Di;

class Mysql extends PhalconMysql
{
    public $isLogger = false;

    public function __construct(array $descriptor)
    {
        parent::__construct($descriptor);
        $this->oLogger = Di::getDefault()->get('logger');
    }

    public function query($sqlStatement, $bindParams = null, $bindTypes = null)
    {
        $oResult = parent::query($sqlStatement, $bindParams, $bindTypes);
        if ($oResult === false && $this->isLogger === false) {
            $trace = debug_backtrace();
            $aCaller = array_shift($trace);
            $sFile = $aCaller['file'];
            $sLine = $aCaller['line'];
           $this->oLogger->error('MySQL query failed. File: ' . $sFile . ', Line: ' . $sLine, ['error' => $this->getErrorInfo()]);
    }
        return $oResult;
    }
}

The line that triggers the error is parent::__construct($descriptor); .

The only other change I've made was to replace the usage of Phalcon\\Db\\Adapter\\Pdo\\Mysql with Internal\\Database\\Mysql . All the connections are created in the same way they were when I were using Phalcon\\Db\\Adapter\\Pdo\\Mysql .

I've looked at the parent classes of Phalcon\\Db\\Adapter\\Pdo\\Mysql . The only place I see the connection created is here

I'd very much appreciate your help with this issue.

Answer 1

It is not a right thing to extend classes in phalcon, that are actually interacting with other php extensions. Learned it the hard way.

The easy way I would recommend is to override Mvc/Model class as a eg. ModelCommon or BaseModel, and implement there Model::initialize and Model::afterFetch .

But a proper way would to be to use event mechanism developed out in Phalcon. The trick is to attach to beforeQuery and/or afterQuery events.

Shortcut for that, done in DI:

$di->set('db', function() use ($di) {
    $config = $di->getConfig();
    $connection = new \Phalcon\Db\Adapter\Pdo\Mysql([
        // ...
    ]);

    $eventsManager->attach('db', function($event, $connection, $params) use ($config) {

        if ($event->getType() == 'beforeQuery') {
            // ...
        }

        if ($event->getType() == 'afterQuery') {
            // ...
        }
    });

    $connection->setEventsManager($eventsManager);
    return $connection;
});

Answer 2

Looks like the module is trying to connect to database more than once. Perhaps make sure you initialise database service just once in your Module.php

Answer 3

Maybe you can db service as shared when you declare db in $di

$di->setShared('db', function() {
    // return your db instance
});

Answer 4

Problem solved, although I still don't understand why it occurred in the first place.

The logger logs to the database, but since it's taken from Di I assumed it reuses existing connection. Removing that line from constructor, and putting it right after the logger is called solved the problem.