PHP responding to ajax when running process

Question

I'm trying to get some data from Ajax request when already PHP running a long script ;

but when the Ajax has been answered that script in PHP is completed, and I need to get Ajax response during running other scripts .

JS

setInterval(function(){
    $.post( 'progress.php','',
    function(data){
        $('.-info-').html(data);
    }); 
},100);

progress.php

session_start();
echo $_SESSION['progress'].'%';

running.php

session_start();
$i=0;
while($i<99){
    $i++;
    $_SESSION['progress'] = $i;
    //sleep(1);
    //flush();
}

Is there any way to response when "while" is running?

Writes about $_SESSION to disk don't happen till the end of the process. The Session file is anyways locked to the serving process, which means the progress.php process will hang till running.php finishes. You'll have to write the progress to your own file and read from there in progress.php. — András Gyömrey
– András Gyömrey, Commented Oct 20, 2014 at 15:49

dognose · Accepted Answer · 2014-10-20 15:55:43Z

1

Edit: Marc B is right. The session will be locked and not updated as required. So you need to store the progress in an system you can access asynchronously from multiple connections - maybe the database?

running.php:

session_start();
$i=0;
while($i<99){
    $i++;
    // Store progress in Database
}

progress.php:

 session_start();
 //read progress from Database

edited Oct 20, 2014 at 15:55

answered Oct 20, 2014 at 15:49

dognose

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2 Comments

talkhabi Over a year ago

I tested all answers , so I got that storing into Database is easy and better .tanQ

talkhabi Over a year ago

I have using progress for copying ,by saving progress in Database and read it by Ajax ... that works fine for small files. but when I chose a file (about more than 100MB) to copy , after a few seconds the all Ajaxs not working .can you help please ? sorry for my bad english

Marc B · Accepted Answer · 2014-10-20 15:48:28Z

1

PHP doesn't dump out a copy of the saved session data every time you update $_SESSION. The session file is actually LOCKED by PHP when any particular process is using it.

You'd need to do:

while($i<99){
    session_start();  // start session
    $i++;
    $_SESSION['progress'] = $i;

    session_write_close();  // save session data, release session file lock

    sleep(...);
}

In other words, your code would never work, as your running script would keep the session open/locked, preventing progress from ever accessing it.

answered Oct 20, 2014 at 15:48

Marc B

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1 Comment

talkhabi Over a year ago

this working ,but still the output ($_SESSION['progress']) is a fixed value?

Vasiliy vvscode Vanchuk · Accepted Answer · 2014-10-20 16:34:55Z

1

use flush() to send output to browser and onreadystatechange to get response at client side

$i=0;
while($i<99){
    $i++;
    echo $i; 
    flush();
    sleep(1);
}

an onreadystatechange will be call on every portion of wata from your script ( http://www.w3schools.com/ajax/ajax_xmlhttprequest_onreadystatechange.asp )

you should check state 3 - State 3 LOADING Downloading; responseText holds partial data. so you easily can use it - you can check it here developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest

edited Oct 20, 2014 at 16:34

answered Oct 20, 2014 at 15:46

Vasiliy vvscode Vanchuk

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9 Comments

András Gyömrey Over a year ago

did you notice which script is he calling from jquery and which one is locking the session file?

dognose Over a year ago

onreadystatechange is fired when the state of the connection changes - not when the content of the page changes.

Vasiliy vvscode Vanchuk Over a year ago

if he'll be print out current status - there is no need to use session - so he can just close session and work with data independently

Vasiliy vvscode Vanchuk Over a year ago

and state changed on every portion of data wile page loading

dognose Over a year ago

well, you are somewhat right. but this will fail for many browsers... IE does not support it at all:

Remarks You cannot call the responseText property to obtain partial results (readyState = 3). Doing so will return an error, because the response is not fully received. You must wait until all data has been received.

msdn.microsoft.com/en-us/library/ie/ms534361(v=vs.85).aspx

|

Shadar · Accepted Answer · 2014-10-20 17:08:39Z

0

You can use a global var but the better in mind is make a static or singleton class

class counter {
  private $_progress=0;

  public static function doProgress() {
    $i=0;
    while($i<99){
    $i++;
    $this->_progress = $i;
    }
  }

  public static function getProgress() {
    return $this->_progress;
  }

so in progress.php do

 echo Counter::getProgress()

and in you javascript you must use setinterval() function in my mermory to call at intervaled time the process.php script

answered Oct 20, 2014 at 17:08

Shadar

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2 Comments

talkhabi Over a year ago

in progress.php we have not class Counter ,and if we define it again , it will be a new class . doesn't?

Vasiliy vvscode Vanchuk Over a year ago

yep. It will be new address space, new process. So static variables won't be shared

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