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Date: Wed, 09 Mar 2011 07:52:31 -0700
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Subject: Re: [PHP-DEV] Make set_time_limit() timeout a catchable fatal error
From: thruska@cubiclesoft.com (Thomas Hruska)

On 3/9/2011 6:56 AM, Hannes Landeholm wrote:
> A simple way to implement this would be to register a function that would be
> called N seconds before the script would timeout.
>
> register_timeout_handler(2, function() { die("PHP timed out."); });
>
> It would be called just as a shutdown function - in fact I'd like to use the
> same function as my shutdown function and get the error with
> error_get_last(). Of course set_time_limit(0) could be used in this function
> to prevent the timeout of the timeout handler. This does not "prevent"
> timeout since set_time_limit could have been called by the script before the
> timeout anyway.

I like this.  Although, I'd rather the first parameter were in 
milliseconds instead of seconds.  This would tell PHP 'x' milliseconds 
before script termination to call the specified function.  That function 
would then have the remainder of the time slice to execute cleanup 
routines and send any errors to the user.  This approach also doesn't 
require a whole new configuration option in php.ini.


> On that note I also miss a function which returns the time the script can
> keep running for. If that calculate needs to be calculated to implemented to
> implement this, why not make the value available to the PHP script?

This is already possible to do.  I do this in WebCron by setting a 
variable with the value of microtime() at the start of execution and 
figuring out how long the script can actually run for.  Then, I stop 
executing a task if there are less than a few seconds left on the clock 
so that there is ample time to clean up gracefully.  For more information:

http://barebonescms.com/documentation/webcron/

Then I expose a convenience function called WC_GetTimeLeft() to modules 
and tasks that can use it to test to see how much time is left on the 
clock to execute the script.  The approach works quite well.  As an 
example, I use WC_GetTimeLeft() extensively in my WebCron Site Backup 
module that can backup websites of any size over HTTP/HTTPS.

http://barebonescms.com/documentation/webcron_site_backup/

So, while it can and has been done, it does require a little extra work 
at the start of the script and obviously isn't as accurate as a 
dedicated function in PHP itself would be.

-- 
Thomas Hruska
CubicleSoft President

Barebones CMS is a high-performance, open source content management 
system for web developers operating in a team environment.

An open source CubicleSoft initiative.
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