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Date: Wed, 9 Mar 2011 16:03:46 +0100
Message-ID: <AANLkTikcEz4f+XyFbw_mQX7XbF-Bamm4b-HVBrwKEWGp@mail.gmail.com>
To: Thomas Hruska <thruska@cubiclesoft.com>, internals@lists.php.net
Content-Type: multipart/alternative; boundary=20cf303bfffc239df5049e0e09e4
Subject: Re: [PHP-DEV] Make set_time_limit() timeout a catchable fatal error
From: landeholm@gmail.com (Hannes Landeholm)

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Content-Type: text/plain; charset=ISO-8859-1

Yes, it's possible to measure the "time left" yourself. However
set_time_limit documentation states that not all time are accounted for when
measuring how long the script can run for. If it's a UNIX system and you're
using system operations/database queries etc there will be a difference
between the time you measure the script has run for and the time PHP has
measured.

And this is only a suitable solution in controlled code like when you're
doing something defined in a loop and can measure the time with regular
intervals. I need it for my framework which can contain any kind of logic,
even logic that uses set_time_limit by itself.

~Hannes

On 9 March 2011 15:52, Thomas Hruska <thruska@cubiclesoft.com> wrote:

> 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.
> Your choice of a MIT or LGPL license.
>
> http://barebonescms.com/
>
>
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