PHP + jQuery - Long Polling with database data aren't working (it doesn't break the loop)

Question

I'm trying to implement a long polling system on my intranetwork, most of the users use IE and some use mobile too, that's why I'm trying to do it with long polling and not with websockets.

I followed this video http://www.screenr.com/SNH and I edited some code to work with my database. (Firebird)

It all seems ok, but it just doesn't break the loop. Maybe it's a kid mistake but I cannot see it, that is why I need your help!

Here's the code:

jQuery + Ajax:

var timestamp = null;

function waitForMsg(){      
    $.ajax({
        type: "GET",
        url: "getData.php?timestamp=" + timestamp,
        async: true,
        cache: false,

        success: function(data){
            alert('It Works');
            var json = eval('(' + data + ')');
            timestamp = json['timestamp'];
            setTimeout('waitForMsg()',15000);
        },
        error: function(XMLHttpRequest, textStatus, errorThrown){
            alert("A - " + XMLHttpRequest + " - error: " + textStatus + " (" + errorThrown + ")");
            setTimeout('waitForMsg()',15000);
        }
    });
}

$(document).ready(function(){
    waitForMsg();
});

</script>

getData.php ('DATAHORA' is timestamp field)

<?php
    set_time_limit(0);
    @ini_set("memory_limit",'64M');

    require_once('../classes/conexao.php');

    $banco = Conexao :: getConexao();
    $sql = "SELECT FIRST 1 DATAHORA FROM AGENDAMENTOSBBM ORDER BY DATAHORA DESC";
    $res = $banco->execute($sql);
    $dados = $banco->fetch($res);
    if($dados)
        $currentmodif = $dados['DATAHORA']);
    else
        $currentmodif = 0;

    $lastmodif = isset($_GET['timestamp']) ? $_GET['timestamp'] : 0;

    while( $currentmodif <= $lastmodif ){
        usleep(10000);
        $sql = "SELECT FIRST 1 DATAHORA FROM AGENDAMENTOSBBM ORDER BY DATAHORA DESC";
        $res = $banco->execute($sql);
        $dados = $banco->fetch($res);
        if($dados)
            $currentmodif = $dados['DATAHORA']);
        else
            $currentmodif = 0;
    }

    $response = array();
    $response['timestamp'] = $currentmodif;
    echo json_encode($response);

?>

When I insert, update, or delete some data, the timestamp field are updated with the current timestamp. I can see that the page enters the loop, but I don't know why it never ends.

Am I doing something wrong?

Thank you

Answer 1

I finaly found the solution.

And it was so simple. My code was not closing the connection with ibase_close

What i did was change it to close when finish the query process. Then inside the loop, i need to reconnect the server again.

OMG how could i forgot that.

Thanks everyone.