Gestion des connexions

Le statut des connexions est conservé en interne par PHP. Il y a trois états possibles :

0 - NORMAL (normal)
1 - ABORTED (annulé)
2 - TIMEOUT (périmé)

Lorsqu'un script PHP est en cours d'exécution, son état est NORMAL. Si le client distant se déconnecte, le statut devient ABORTED. En général, une telle déconnexion provient d'un arrêt temporaire. Si la durée maximale d'exécution de PHP est dépassée, (voir set_time_limit()), le script prend le statut TIMEOUT.

Vous pouvez en outre décider si vous voulez que la déconnexion d'un client provoque l'arrêt de votre script. Il est parfois pratique que vos scripts continuent à s'exécuter jusqu'à la fin, même si le client n'est plus là pour recevoir les informations. Cependant, par défaut, le script s'arrêtera dès que le client se déconnecte. Ce comportement peut être modifié avec la directive ignore_user_abort dans le fichier php.ini ou bien avec la directive Apache php_value ignore_user_abort du fichier Apache httpd.conf ou avec la fonction ignore_user_abort(). Si vous ne demandez pas à PHP d'ignorer la déconnexion, et que l'utilisateur se déconnecte, le script sera terminé. La seule exception est si vous avez enregistré une fonction de fermeture, avec register_shutdown_function(). Avec une telle fonction, lorsque l'utilisateur interrompt sa requête, à la prochaine exécution du script, PHP va s'apercevoir que le dernier script n'a pas été terminé, et il va déclencher la fonction de fermeture. Cette fonction sera aussi appelée à la fin du script, si celui-ci se termine normalement. Pour pouvoir avoir un comportement différent suivant l'état du script lors de sa finalisation, vous pouvez exécutez des commandes spécifiques à la déconnexion grâce à la commande connection_aborted(). Cette fonction retournera TRUE si la connexion a été annulée.

Votre script peut aussi être automatiquement interrompu après une certaine durée. Par défaut, le délai est de 30 secondes. Cette valeur peut être changée en utilisant la directive PHP max_execution_time dans le fichier php.ini ou avec la directive php_value max_execution_time, dans le fichier Apache httpd.conf ou encore avec la fonction set_time_limit(). Lorsque le délai expire, le script est terminé, et comme pour la déconnexion du client, une fonction de terminaison sera appelée. Dans cette fonction, vous pouvez savoir si c'est le délai d'expiration qui a causé la fin du script, en appelant la fonction connection_status(). Cette fonction retournera 2 si le délai d'expiration a été dépassé.

Une chose à noter est que les deux cas ABORTED et TIMEOUT peuvent être appelés en même temps. Ceci est possible si vous demandez à PHP d'ignorer les déconnexions des utilisateurs. PHP va quand même noter le fait que l'utilisateur s'est déconnecté, mais le script va continuer. Puis, lorsqu'il atteint la limite de temps, le script va expirer. À ce moment-là, la fonction connection_status() retournera 3.

Connexions persistantes aux bases de données

Utilisation des fichiers à distance

Last updated: Fri, 20 Jun 2008

add a note User Contributed Notes
Gestion des connexions

Jean Charles MAMMANA
02-Apr-2008 05:25


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 06:06


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
15-Nov-2006 03:51


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 09:42


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
13-Dec-2004 03:08


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 06:16


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 09:01


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 02:32


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.

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Connexions persistantes aux bases de données

Utilisation des fichiers à distance

Last updated: Fri, 20 Jun 2008