Usando arquivos remotos
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...
Tratamento de Conexões
O status de uma conexão é mantido internamente no PHP. Existem 3 estados possíveis:
- 0 - NORMAL
- 1 - ABORTED
- 2 - TIMEOUT
Quando um script PHP está sendo executado normalmente, o estado NORMAL está ativo. Se o cliente remoto desconecta, o estado ABORTED (abortado) é ligado. Uma desconexão do cliente remoto é normalmente causada pelo usuário apertando o botão STOP. Se o tempo limite imposto pelo PHP (veja set_time_limit()) é alcançado, o estado TIMEOUT (tempo acabado) é ligado.
Você pode decidir se quer ou não que a desconexão do cliente cause que seu script seja abortado. As vezes é útil sempre fazer o seu script rodar até completar mesmo se não há nenhum navegador remoto recebendo a saída. O comportamento padrão, no entanto, é de seu script ser abortado quando o cliente remoto desconecta. Esse comportamento pode ser configurado através da diretiva ignore_user_abort php.ini assim como pela diretiva correspondente do Apache .conf, "php_value ignore_user_abort" ou com a função ignore_user_abort(). Se você não disser para o PHP ignorar o abort do usuário e ele abortar, seu script será finalizado. A única exceção é se você tiver registrado uma função de finalização usando register_shutdown_function(). Com uma função de finalização, quando um usuário remoto clica no botão STOP, a próxima vez que seu script tentar gerar alguma saída, o PHP detectará que a conexão foi abortada e a função de finalização é chamada. Essa função de finalização também será chamada no fim do seu script mesmo terminando normalmente, então para fazer algo diferente caso o cliente desconecte, você pode usar a função connection_aborted(). Essa função retorna TRUE se a conexão foi abortada.
Seu script também pode ser finalizado pelo timer interno. O tempo limite padrão é de 30 segundos. Pode ser mudado usando a diretiva max_execution_time php.ini ou a diretiva do Apache .conf correspondente php_value max_execution_time assim como com a função set_time_limit(). Quando o timer chega ao limite, o script será abortado e assim como o caso acima de desconexão, se uma função de finalização foi registrada, ela será chamada. Dentro da função de finalização você pode checar se a causa da finalização foi estouro do tempo limite chamando a função connection_timeout(). Essa função retornará TRUE se o a função de finalização foi chamada pelo tempo ter acabado.
Uma coisa a ser notada é que ambos os estados ABORTED e TIMEOUT podem estar ligados ao mesmo tempo. Isso é possível se você disser ao PHP para ignorar o abort do usuário. O PHP continuará a notar o fato que o usuário pode ter quebrado a conexão, mas o script continuará executando. Se então ele alcançar o tempo limite, ele será abortado e sua função de finalização, se houver, será chamada. Nesse ponto, você terá que connection_status() retorna 3.
add a note
User Contributed NotesTratamento de Conexões
Jean Charles MAMMANA
02-Apr-2008 12:25
02-Apr-2008 12:25
Anonymous
13-Nov-2007 12:06
13-Nov-2007 12:06
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 09:51
14-Nov-2006 09:51
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 04:42
22-Sep-2005 04:42
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 09:08
12-Dec-2004 09:08
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 01:16
18-Sep-2004 01:16
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 03:01
12-Feb-2004 03:01
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 09:32
07-Aug-2003 09:32
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.