register_shutdown_function()

(PHP 4, PHP 5, PHP 7)

注册一个会在php中止时执行的函数

说明

注册一个$callback，它会在脚本执行完成或者exit()后被调用。

可以多次调用register_shutdown_function()，这些被注册的回调会按照他们注册时的顺序被依次调用。如果你在注册的方法内部调用exit()，那么所有处理会被中止，并且其他注册的中止回调也不会再被调用。

参数

待注册的中止回调

中止回调是作为请求的一部分被执行的，因此可以在它们中进行输出或者读取输出缓冲区。

可以通过传入额外的参数来将参数传给中止函数

返回值

没有返回值。

错误／异常

如果传入的callback不是可调用的，那么将会产生一个E_WARNING级别的错误。

范例

Example #1register_shutdown_function()例子

注释

在某些web server（如Apache）上，可以在中止函数内对脚本的工作目录进行修改。Note:

如果进程被信号SIGTERM或SIGKILL杀死，那么中止函数将不会被调用。尽管你无法中断SIGKILL，但你可以通过pcntl_signal()来捕获SIGTERM，通过在其中调用exit()来进行一个正常的中止。

参见

• auto_append_file
• exit() 输出一个消息并且退出当前脚本
• 连接处理章节

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!

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)

In PHP 5.1.6 things don't work as described here.
The truth is that connection_status() just always returns 0 whether or not the client has aborted (e.g. the user hit the stop button), and that (consistently with this) the registered shutdown function will only be called on exit, but NOT when the connection is aborted from the user.
That is, PHP does NOT detect when the connection is aborted.

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.

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:

A simple application:

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!

The following function register_close_function should reproduce the former php behavior of closing the connection before executing the shutdown handler, based on the code posted by sts at mail dot xubion dot hu. It does not work on any machine. 

Given this code:

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