register_shutdown_function

(PHP 4, PHP 5, PHP 7, PHP 8)

register_shutdown_functionRegistra una función de retrollamada para ejecución al cierre

Descripción

register_shutdown_function(callable $callback, mixed ...$args): void

Registra una función de retrollamada callback para ejecución al cierre o cuando exit() es llamado.

Varios llamados a register_shutdown_function() son posibles en el mismo script, y las funciones serán llamadas en el mismo orden en que son registradas. Si se llama exit() durante una de las funciones de cierre, el proceso será definitivamente detenido, sin que las otras funciones sean llamadas.

Las funciones de cierre pueden también llamar a la función register_shutdown_function() ellas mismas para añadir una función de cierre al final de la cola.

Parámetros

callback

La función de retrollamada a registrar.

La función de retrollamada es ejecutada como parte de la petición, por lo tanto, es posible enviar algo a la salida desde esta última, así como acceder a los buffers de salida.

args

Es posible pasar argumentos a las funciones de cierre configurando estos argumentos adicionales.

Valores devueltos

No devuelve ningún valor.

Ejemplos

Ejemplo #1 Ejemplo con register_shutdown_function()

<?php
function shutdown()
{
// Aquí está nuestra función shutdown
// en la cual podemos realizar
// todas las últimas operaciones
// antes del fin del script.

echo 'Script ejecutado con éxito', PHP_EOL;
}

register_shutdown_function('shutdown');
?>

Notas

Nota:

El directorio de trabajo del script puede cambiar en la función de cierre bajo algunos servidores web, por ejemplo Apache.

Nota:

Las funciones de cierre no serán ejecutadas si el proceso es terminado con un señal SIGTERM o SIGKILL. Aunque no se puede interceptar un SIGKILL, se puede usar la función pcntl_signal() para instalar un manejador para un SIGTERM que utilice la función exit() para terminar correctamente.

Nota:

Las funciones de cierre se ejecutan por separado del tiempo seguido por max_execution_time. Esto significa que incluso si un proceso es terminado por haber funcionado demasiado tiempo, las funciones de cierre serán siempre llamadas. Además, si el max_execution_time alcanza su límite mientras una función de cierre está en ejecución, no será interrumpida.

Ver también

add a note

User Contributed Notes 14 notes

up
256
jules at sitepointAASASZZ dot com
22 years ago
If your script exceeds the maximum execution time, and terminates thusly:

Fatal error: Maximum execution time of 20 seconds exceeded in - on line 12

The registered shutdown functions will still be executed.

I figured it was important that this be made clear!
up
81
http://livejournal.com/~sinde1/
19 years ago
If you want to do something with files in function, that registered in register_shutdown_function(), use ABSOLUTE paths to files instead of relative. Because when script processing is complete current working directory chages to ServerRoot (see httpd.conf)
up
14
pgl at yoyo dot org
15 years ago
You definitely need to be careful about using relative paths in after the shutdown function has been called, but the current working directory doesn't (necessarily) get changed to the web server's ServerRoot - I've tested on two different servers and they both have their CWD changed to '/' (which isn't the ServerRoot).

This demonstrates the behaviour:

<?php
function echocwd() { echo 'cwd: ', getcwd(), "\n"; }

register_shutdown_function('echocwd');
echocwd() and exit;
?>

Outputs:

cwd: /path/to/my/site/docroot/test
cwd: /

NB: CLI scripts are unaffected, and keep their CWD as the directory the script was called from.
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21
emanueledelgrande ad email dot it
14 years ago
A lot of useful services may be delegated to this useful trigger.
It is very effective because it is executed at the end of the script but before any object destruction, so all instantiations are still alive.

Here's a simple shutdown events manager class which allows to manage either functions or static/dynamic methods, with an indefinite number of arguments without using any reflection, availing on a internal handling through func_get_args() and call_user_func_array() specific functions:

<?php
// managing the shutdown callback events:
class shutdownScheduler {
private
$callbacks; // array to store user callbacks

public function __construct() {
$this->callbacks = array();
register_shutdown_function(array($this, 'callRegisteredShutdown'));
}
public function
registerShutdownEvent() {
$callback = func_get_args();

if (empty(
$callback)) {
trigger_error('No callback passed to '.__FUNCTION__.' method', E_USER_ERROR);
return
false;
}
if (!
is_callable($callback[0])) {
trigger_error('Invalid callback passed to the '.__FUNCTION__.' method', E_USER_ERROR);
return
false;
}
$this->callbacks[] = $callback;
return
true;
}
public function
callRegisteredShutdown() {
foreach (
$this->callbacks as $arguments) {
$callback = array_shift($arguments);
call_user_func_array($callback, $arguments);
}
}
// test methods:
public function dynamicTest() {
echo
'_REQUEST array is '.count($_REQUEST).' elements long.<br />';
}
public static function
staticTest() {
echo
'_SERVER array is '.count($_SERVER).' elements long.<br />';
}
}
?>

A simple application:

<?php
// a generic function
function say($a = 'a generic greeting', $b = '') {
echo
"Saying {$a} {$b}<br />";
}

$scheduler = new shutdownScheduler();

// schedule a global scope function:
$scheduler->registerShutdownEvent('say', 'hello!');

// try to schedule a dyamic method:
$scheduler->registerShutdownEvent(array($scheduler, 'dynamicTest'));
// try with a static call:
$scheduler->registerShutdownEvent('scheduler::staticTest');

?>

It is easy to guess how to extend this example in a more complex context in which user defined functions and methods should be handled according to the priority depending on specific variables.

Hope it may help somebody.
Happy coding!
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26
ravenswd at gmail dot com
15 years ago
You may get the idea to call debug_backtrace or debug_print_backtrace from inside a shutdown function, to trace where a fatal error occurred. Unfortunately, these functions will not work inside a shutdown function.
up
8
RLK
16 years ago
Contrary to the the note that "headers are always sent" and some of the comments below - You CAN use header() inside of a shutdown function as you would anywhere else; when headers_sent() is false. You can do custom fatal handling this way:

<?php
ini_set
('display_errors',0);
register_shutdown_function('shutdown');

$obj = new stdClass();
$obj->method();

function
shutdown()
{
if(!
is_null($e = error_get_last()))
{
header('content-type: text/plain');
print
"this is not html:\n\n". print_r($e,true);
}
}
?>
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5
dweingart at pobox dot com
19 years ago
I have discovered a change in behavior from PHP 5.0.4 to PHP 5.1.2 when using a shutdown function in conjunction with an output buffering callback.

In PHP 5.0.4 (and earlier versions I believe) the shutdown function is called after the output buffering callback.

In PHP 5.1.2 (not sure when the change occurred) the shutdown function is called before the output buffering callback.

Test code:
<?php
function ob_callback($buf) {
$buf .= '<li>' . __FUNCTION__ .'</li>';
return
$buf;
}

function
shutdown_func() {
echo
'<li>' . __FUNCTION__ .'</li>';
}

ob_start('ob_callback');
register_shutdown_function('shutdown_func');
echo
'<ol>';
?>

PHP 5.0.4:

1. ob_callback
2. shutdown_func

PHP 5.1.2:

1. shutdown_func
2. ob_callback
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2
jawsper at aximax dot nl
15 years ago
Something found out during testing:

the ini auto_append_file will be included BEFORE the registered function(s) will be called.
up
7
alexyam at live dot com
13 years ago
When using php-fpm, fastcgi_finish_request() should be used instead of register_shutdown_function() and exit()

For example, under nginx and php-fpm 5.3+, this will make browsers wait 10 seconds to show output:

<?php
echo "You have to wait 10 seconds to see this.<br>";
register_shutdown_function('shutdown');
exit;
function
shutdown(){
sleep(10);
echo
"Because exit() doesn't terminate php-fpm calls immediately.<br>";
}
?>

This doesn't:

<?php
echo "You can see this from the browser immediately.<br>";
fastcgi_finish_request();
sleep(10);
echo
"You can't see this form the browser.";
?>
up
1
kenneth dot kalmer at gmail dot com
19 years ago
I performed two tests on the register_shutdown_function() to see under what conditions it was called, and if a can call a static method from a class. Here are the results:

<?php
/**
* Tests the shutdown function being able to call a static methods
*/
class Shutdown
{
public static function
Method ($mixed = 0)
{
// we need absolute
$ap = dirname (__FILE__);
$mixed = time () . " - $mixed\n";
file_put_contents ("$ap/shutdown.log", $mixed, FILE_APPEND);
}
}
// 3. Throw an exception
register_shutdown_function (array ('Shutdown', 'Method'), 'throw');
throw new
Exception ('bla bla');

// 2. Use the exit command
//register_shutdown_function (array ('Shutdown', 'Method'), 'exit');
//exit ('exiting here...')

// 1. Exit normally
//register_shutdown_function (array ('Shutdown', 'Method'));
?>

To test simply leave one of the three test lines uncommented and execute. Executing bottom-up yielded:

1138382480 - 0
1138382503 - exit
1138382564 - throw

HTH
up
1
sts at mail dot xubion dot hu
21 years ago
If you need the old (<4.1) behavior of register_shutdown_function you can achieve the same with "Connection: close" and "Content-Length: xxxx" headers if you know the exact size of the sent data (which can be easily caught with output buffering).
An example:
<?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");
?>

The same will work with registered functions.
According to http spec, browsers should close the connection when they got the amount of data specified in Content-Length header. At least it works fine for me in IE6 and Opera7.
up
1
josh at joshstrange dot com
1 year ago
> Shutdown functions run separately from the time tracked by max_execution_time. That means even if a process is terminated for running too long, shutdown functions will still be called. Additionally, if the max_execution_time runs out while a shutdown function is running it will not be terminated.

This does not appear to be true in our testing, specifically "Additionally, if the max_execution_time runs out while a shutdown function is running it will not be terminated". For example:

<?php
set_time_limit
(5);

register_shutdown_function(function() {
$start = time();
for(
$i = 0; $i < 40; $i++) {
echo
"Run 1: $i\n";
while(
1) {
$elapsed = time() - $start;
if(
$elapsed > $i) {
break;
}
}
}
});

?>

This will print out:

Run 1: 0
Run 1: 1
Run 1: 2
Run 1: 3
Run 1: 4
Run 1: 5

Then it will die with:

Execution took longer than 5 seconds, sent SIGTERM and terminated

If you register multiple shutdown functions and an earlier one exceeds the execution time the later ones will _not_ be run.

If you need your shutdowns to have unlimited time (like the docs suggest it works) one solution might be to register a shutdown function like this early in your code:

<?php
register_shutdown_function
(function() {
set_time_limit(0);
});
?>

So that you give yourself unlimited time in your subsequent shutdown functions.

See an example here: https://www.tehplayground.com/wJLtMi3Z5c1sTi9Y (Note, 5 seconds is the max you can set on this website. If you remove the first shutdown function you it will be killed after 3 seconds).
up
2
raat1979 at gmail dot com
8 years ago
I wanted to set the exit code for a CLI application from a shutdown function by using a class property,

Unfortunataly (as per manual) "If you call exit() within one registered shutdown function, processing will stop completely and no other registered shutdown functions will be called."

As a result if I call exit in my shutdown function I will break other shutdown functions (like one that logs fatal errors to syslog)

However! (as per manual) "Multiple calls to register_shutdown_function() can be made, and each will be called in the same order as they were registered."

As luck would have it you are also able to register a shutdown function from within a shutdown function (at least in PHP 7.0.15 and 5.6.30)

in other words if you register a shutdown function inside a shutdown function it is appended to the shutdown function queue.

<?php
class SomeApplication{
private
$exitCode = null;

public function
__construct(){
register_shutdown_function(function(){
echo
"some registered shutdown function";
register_shutdown_function(function(){
echo
"last registered shutdown function";
// one might even consider another register shutdown_function if one expects other shutdown functions to do the same...
exit($this->exitCode === null ? 0 : $this->exitCode);
});
});
}
}
?>
up
-1
Anonymous
6 years ago
warning: in addition to SIGTERM and SIGKILL, the shutdown functions won't run in response to SIGINT either. (observed on php 7.1.16 on windows 7 SP1 x64 + cygwin and php 7.2.15 on Ubuntu 18.04)
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