Het gebruik van remote bestanden
hey, thanks to arr1, and it is very useful for me, when I need to return to the user fast and then do something else.
When using the codes, it nearly drive me mad and I found another thing that may affect the codes:
Content-Encoding: gzip
This is because the zlib is on and the content will be compressed. But this will not output the buffer until all output is over.
So, it may need to send the header to prevent this problem.
now, the code becomes:
<?php
ob_end_clean();
header("Connection: close\r\n");
header("Content-Encoding: none\r\n");
ignore_user_abort(true); // optional
ob_start();
echo ('Text user will see');
$size = ob_get_length();
header("Content-Length: $size");
ob_end_flush(); // Strange behaviour, will not work
flush(); // Unless both are called !
ob_end_clean();
//do processing here
sleep(5);
echo('Text user will never see');
//do some processing
?>
Connection handling
Note: Het volgende is alleen actief in PHP 3.0.7 en hoger.
Intern in PHP wordt de connectie status bijgehouden. Er zijn 3 mogelijke statussen mogelijk:
- 0 - NORMAL
- 1 - ABORTED
- 2 - TIMEOUT
Als een PHP script normaal draait is de NORMAL status actief. Zogauw een gebruiker de HTTP connectie sluit is de ABORTED status actief. Dit gebeurt meestal als de gebruiker op z'n STOP knop klikt. Als de door PHP bijgehouden tijdlimiet (zie set_time_limit()) overschreden word, is de TIMEOUT status actief.
Je kunt er voor kiezen jouw script te beëindigen wanneer een gebruiker de connectie met de server sluit, echter is het soms handig om een script door te laten lopen, zelfs als er geen browser is om de output te ontvangen. Standaard wordt echter jouw script gestopt wanneer de gebruiker de connectie sluit. Dit gedrag kan gewijzigd worden met de ignore_user_abort php.ini directive of met de corresponderende php_ignore_user_abort Apache .conf directive of het makkelijkst met de ignore_user_abort() functie. Als je PHP niet vertelt het sluiten van een connectie te negeren zal je script gestopt worden zogauw dit gebeurd. Er is een uitzondering, als je een shutdown functie hebt geregistreerd met de register_shutdown_function() functie zal PHP zogauw hij ontdekt dat er geen connectie meer is, proberen deze shutdown functie aan te roepen. Deze functie wordt echter ook aangeroepen als je script op een normale manier eindigt. Als je alleen actie wilt ondernemen als de gebruiker de connectie sluit kun je gebruik maken van de connection_aborted() functie. Deze functie geeft TRUE als de connectie gesloten is.
Jouw script kan ook beëindigd worden door de ingebouwde script timer. De standaard timeout is 30 seconden. Dit kan veranderd worden met de max_execution_time php.ini directive of met de corresponderende php_max_execution_time Apache .conf directive alsmede met de set_time_limit() functie. Als de toegestane tijd word overschreden wordt het script beëindigd en net zoals in het geval dat de gebruiker de connectie sluit word er een shutdown functie aangeroepen mits deze geregistreerd is. In deze shutdown functie kun je controleren of een timeout de oorzaak is van het aanroepen van de shutdown function. Dit doe je met de connection_timeout() functie. Deze functie geeft TRUE als een timeout de oorzaak was.
Een ding om te onthouden is dat de ABORTED status en de TIMEOUT status allebei actief kunnen zijn op het zelfde moment. Dit is pas mogelijk als je PHP verteld om zgn. 'user aborts' (gebruikt sluit connectie) te negeren. PHP zal merken dat de gebruiker de connectie gesloten heeft maar het script blijft draaien. Als het tijdslimiet bereikt word, wordt het script beëindigd en de shutdown functie aangeroepen. Je zal merken dat als dit het geval is zowel connection_timeout() als connection_aborted() TRUE geven. Je kunt deze statussen met 1 functie controleren, namelijk connection_status(). Deze functie geeft een bitfield met de huidig actieve statussen. Dus als beide statussen actief zijn zou het 3 geven.
add a note
User Contributed NotesConnection handling
tom lgold2003 at gmail dot com
10-Sep-2009 08:43
10-Sep-2009 08:43
alan at burrist dot co dot uk
25-Feb-2009 01:57
25-Feb-2009 01:57
A simple but useful packaging of arr1's suggestion for continuing processing after telling the the browser that output is finished.
I always redirect when a request requires some processing (so we don't do it twice on refresh) which makes things easy...
<?php
function redirect_and_continue($sURL)
{
header( "Location: ".$sURL ) ;
ob_end_clean(); //arr1s code
header("Connection: close");
ignore_user_abort();
ob_start();
header("Content-Length: 0");
ob_end_flush();
flush(); // end arr1s code
session_write_close(); // as pointed out by Anonymous
}
?>
Of course this wont work if the output has started - but the a simple redirect wouldn't work anyway.
Thanks for the tip arr1
fanfear at yahoo dot com
05-Jan-2009 10:59
05-Jan-2009 10:59
i use this code when i want php infinite loop
<?php
set_time_limit (0);//run script forever
ignore_user_abort ();//run script in background
$i = 0;
echo "start\n";
while (1) {
$i++;
echo $i, "\n";
$sleep = sleep (3);
if ($sleep == 0 or $sleep or $sleep == FALSE) continue;
if (connection_aborted ()) continue;
if (connection_status () != 0) continue;
}
?>
Jean Charles MAMMANA
01-Apr-2008 11:25
01-Apr-2008 11:25
connection_status() return ABORTED state ONLY if the client disconnects gracefully (with STOP button). In this case the browser send the RST TCP packet that notify PHP the connection is closed.
But.... If the connection is stopped by networs troubles (wifi link down by exemple) the script doesn't know that the client is disconnected :(
I've tried to use fopen("php://output") with stream_select() on writting to detect write locks (due to full buffer) but php give me this error : "cannot represent a stream of type Output as a select()able descriptor"
So I don't know how to detect correctly network trouble connection...
Anonymous
13-Nov-2007 11:06
13-Nov-2007 11:06
in regards of posting from:
arr1 at hotmail dot co dot uk
if you use/write sessions you need to do this before:
(otherwise it does not work)
session_write_close();
and if wanted:
ignore_user_abort(TRUE);
instead of ignore_user_abort();
arr1 at hotmail dot co dot uk
14-Nov-2006 08:51
14-Nov-2006 08:51
Closing the users browser connection whilst keeping your php script running has been an issue since 4.1, when the behaviour of register_shutdown_function() was modified so that it would not automatically close the users connection.
sts at mail dot xubion dot hu
Posted the original solution:
<?php
header("Connection: close");
ob_start();
phpinfo();
$size=ob_get_length();
header("Content-Length: $size");
ob_end_flush();
flush();
sleep(13);
error_log("do something in the background");
?>
Which works fine until you substitute phpinfo() for
echo ('text I want user to see'); in which case the headers are never sent!
The solution is to explicitly turn off output buffering and clear the buffer prior to sending your header information.
example:
<?php
ob_end_clean();
header("Connection: close");
ignore_user_abort(); // optional
ob_start();
echo ('Text the user will see');
$size = ob_get_length();
header("Content-Length: $size");
ob_end_flush(); // Strange behaviour, will not work
flush(); // Unless both are called !
// Do processing here
sleep(30);
echo('Text user will never see');
?>
Just spent 3 hours trying to figure this one out, hope it helps someone :)
Tested in:
IE 7.5730.11
Mozilla Firefox 1.81
bg at ms dot com
22-Sep-2005 03:42
22-Sep-2005 03:42
Confirmed. User presses STOP button. This sends a RST packet and closes the connection. PHP is most certainly immediately affected (i.e., the script is stopped, whether or not any output is pending for the user, or even if script is just grinding away on a database without having output anything).
ignore_user_abort() exists to prevent this.
If user STOPS, script ignores the RST and runs to completion (the output is apparently ignored by apache and not sent to the user, who sent the RST and closed the TCP connection). If user's connection just vanishes (isp problem, disconnect, whatever), and there is no RST sent by user, then eventually the script will timeout.
hrgan at melibado dot com
12-Dec-2004 08:08
12-Dec-2004 08:08
As it was said, connection handling is very useful when web application need to do something in background. I found it very useful when application need something from database, wrap that data with template, create some html files and save it to filesystem. And all that on server with heavy load. Without connection handling - function ignore_user_abort() - this process can be interrupted by user and final step will never be done.
Lee
18-Sep-2004 12:16
18-Sep-2004 12:16
The point mentioned in the last comment isn't always the case.
If a user's connection is lost half way through an order processing script is confirming a user's credit card/adding them to a DB, etc (due to their ISP going down, network trouble... whatever) and your script tries to send back output (such as, "pre-processing order" or any other type of confirmation), then your script will abort -- and this could cause problems for your process.
I have an order script that adds data to a InnoDB database (through MySQL) and only commits the transactions upon successful completion. Without ignore_user_abort(), I have had times when a user's connection dropped during the processing phase... and their card was charged, but they weren't added to my local DB.
So, it's always safe to ignore any aborts if you are processing sensitive transactions that should go ahead, whether your user is "watching" on the other end or not.
ej at campbell *dot* name
12-Feb-2004 02:01
12-Feb-2004 02:01
I don't think the first example given below will occur in the real world.
As long as your order handling script does not output anything, there's no way that it will be aborted before it completes processing (unless it timeouts). PHP only senses user aborts when a script sends output. If there's no output sent to the client before processing completes, which is presumably the case for an order handling script, the script will run to completion.
So, the only time a script can be terminated due to the user hitting stop is when it sends output. If you don't send any output until processing completes, you don't have to worry about user aborts.
pulstar at mail dot com
07-Aug-2003 08:32
07-Aug-2003 08:32
These functions are very useful for example if you need to control when a visitor in your website place an order and you need to check if he/she didn't clicked the submit button twice or cancelled the submit just after have clicked the submit button.
If your visitor click the stop button just after have submitted it, your script may stop in the middle of the process of registering the products and do not finish the list, generating inconsistency in your database.
With the ignore_user_abort() function you can make your script finish everything fine and after you can check with register_shutdown_function() and connection_aborted() if the visitor cancelled the submission or lost his/her connection. If he/she did, you can set the order as not confirmed and when the visitor came back, you can present the old order again.
To prevent a double click of the submit button, you can disable it with javascript or in your script you can set a flag for that order, which will be recorded into the database. Before accept a new submission, the script will check if the same order was not placed before and reject it. This will work fine, as the script have finished the job before.
Note that if you use ob_start("callback_function") in the begin of your script, you can specify a callback function that will act like the shutdown function when our script ends and also will let you to work on the generated page before send it to the visitor.