Chat system in php with long pool, how to send and get msg together without so much delay time

Question

im currently developing a chat aplication in php to a client using long polling. When the user send msgs i woud .abort() the getmsg() function and restart in on sendmsg() sucess (ajax call), but if the user send repeatedly msgs, the getmsg() get fired multiple times with same parameters, and if the other user is sending msgs too, i got repeatedly the same msgs. I got a way around it, without .abort() the getmsg() in sendmsg() it works well (ajax take care of both calls). But when the user send repeatedly msgs, i need to wait in the sleep() loop (getmsg()) to get all the msgs, even if there only a word in each. Is there a way to make the abort() fire just one time on consecutive msgs, or how i could make the sleep() to go lower (less seconds) when it finds a message? Wouldt it take so much of the server to do this check everytime? Thanks in advance, sorry for too long text. Here`s the functions:

PHP

getmsg() (a php file, this is the function)
$aa = mysql_num_rows($chatresult);
$togetmsg = 2;
while($aa == 0 && $tried_times < 6) {

sleep($togetmsg);
$chatresult = mysql_query("query"); 
$aa = mysql_num_rows($chatresult);
$tried_times++;
}

while($crow = mysql_fetch_assoc($chatresult))
{
 get the messages and put in a var/array;       

} 
json_encode the msgs

sendmsg()

 Just a query to insert the textarea value in the table.

JAVASCRIPT

getmsg() :

  jack = $.ajax({
        type: "POST",
        url: "getmsg.php",
        data: {friend_chatid: friend_chatid, msg_id: msg_id},
        dataType: 'json',
        context: this,
        async: true,
        cache: false,
        timeout:30000,

        success: function(html){      
            $(this).find(".div").append(message);
            msg_id = 0;

            var _this = $(this);     
            setTimeout(
                getmsg, /* Request next message */
                1000 /* ..after 1 seconds */
            );
        },
        error: function(XMLHttpRequest, textStatus, errorThrown){
         if(textStatus==="abort" || errorThrown==="abort") {
     //   alert(textStatus);
    } else {
            setTimeout(
                getmsg, 
                3000);
    }



        }
    });

SENDMSG()

$.ajax({
type: "POST",
url: "sendmsg.php",
data: {msg: msg, to: to},
context: this,
cache: false,
beforeSend: function () {
//   jack.abort(); // Commented cause i`m not using it now
$(this).val('');
    $(".div").append(msg); //

 },
success: function(html){
    //    getmsg(); // Commented cause i`m not using it now
  }
});  

It`s resumed, i take out the appending data part, to make it better to read. The sendmsg() in javascript append the textarea value to the chat and them send it to the db with php when the user press enter and textarea have text (i take out this part for better reading). The getmsg() gets on a while loop checking if there are existing msgs using mysql_num_rows and echo them back if any.

Answer 1

I think it can be fixed using clearTimeout. Just try this code.

Function sendmsg()

// define a variable named `pollQueue` outsode of your function
var pollQueue = false;

// send message
$.ajax({
  type: "POST",
  url: "sendmsg.php",
  data: { msg : msg, to : to },
  context: this,
  cache: false,
  beforeSend: function() {
    // Check if getmsg is in queue
    if ( pollQueue ) {
      // if so clear the queue
      clearTimeout( pollQueue );
    }
    if ( jack ) {
      jack.abort();
    }
    $(this).val('');
    $(".div").append( msg );
  },
  success: function( html ) {
    // add to queue
    pollQueue = setTimeout( getmsg, 3000 );
  }
});