[Rd] interrupting native code
Simon Urbanek
simon.urbanek at r-project.org
Tue May 20 19:22:34 CEST 2008
On May 20, 2008, at 10:58 AM, Kjell Konis wrote:
> I would actually prefer a mechanism that simply returns a flag
> indicating that an interrupt has been requested. Then I would be
> able to clean up and return on my own - no longjmp required. Also,
> it would be useful if there was a function similar to
> R_ProcessEvents that only dealt with keeping the GUI responsive.
>
I don't understand what you mean by the last sentence - that is
exactly what R_ProcessEvents is for - or am I missing something?
Cheers,
Simon
> Cheers,
> Kjell
>
>
> On 16 mai 08, at 13:54, Luke Tierney wrote:
>
>> I'm not sure you can make this work as some of the things needed
>> either are or should be private to the core implementation and not
>> available to package code. In any case I would not recommend this
>> approach for two reasons. First, details of what happens in
>> interrupt
>> checking are subject to change and your code would miss those changes
>> unless you track them carefully. More importantly, several things
>> here could generate an error that results in a longjmp and leaves
>> your
>> code in an unstable state.
>>
>> What is needed for this is a mechanism for detecting an interrupt but
>> not doing the longjmp, just returning a flag that a longjmp is needed
>> and enough information to allow it to be made after cleanup code has
>> been run. This has been on my to do list for a while but getting the
>> semantics right is tricky and so it hasn't happened yet. Hopefully
>> it
>> will be in 2.8.0. In the interim you can cobble something together
>> using R_ToplevelExec, interpreting all FALSE return values as user
>> interrupts.
>>
>> Another option, also under consideration but not available yet, is
>> a C
>> mechanism for registering cleanup operations if a longjmp occurs. A
>> quick and dirty version of that could be provided fairly easily but a
>> better version, which would be preferable in the long run, requires a
>> rewrite of the code that implements jumps and cleanup/on.exit
>> actions.
>> This may take a bit longer to implement.
>>
>> Best,
>>
>> luke
>>
>> On Fri, 16 May 2008, Kjell Konis wrote:
>>
>>> You mean something like this (I return 1 instead of calling
>>> onintr())? Will HAVE_AQUA and Win32 be appropriately defined when
>>> building my package (I can't see how to check with R CMD config)?
>>>
>>> int My_CheckUserInterrupt(void)
>>> {
>>> R_CheckStack();
>>>
>>> #if ( defined(HAVE_AQUA) )
>>>
>>> /* R_ProcessEvents() from unix/aqua.c*/
>>>
>>> if (ptr_R_ProcessEvents)
>>> ptr_R_ProcessEvents();
>>> if (R_interrupts_pending)
>>> return(1);
>>>
>>> #elseif ( defined(Win32) )
>>>
>>> /* R_ProcessEvents() from gnuwin32/system.c */
>>>
>>> while (peekevent()) doevent();
>>> if (UserBreak) {
>>> UserBreak = FALSE;
>>> return(1);
>>> }
>>> R_CallBackHook();
>>> if(R_tcldo) R_tcldo();
>>>
>>> #else
>>>
>>> R_PolledEvents();
>>> if (R_interrupts_pending)
>>> return(1);
>>>
>>> #endif
>>>
>>> return(0);
>>> }
>>>
>>>
>>>
>>>
>>> On 16 mai 08, at 12:43, Prof Brian Ripley wrote:
>>>
>>>> On Fri, 16 May 2008, Kjell Konis wrote:
>>>>> The problem is that my package uses an external pointer to keep
>>>>> track of a structure created by the lp_solve library. If I use
>>>>> R_CheckUserInterrupt in the lp_solve abort function it leaves
>>>>> the structure in a messed-up state after an interrupt occurs. I
>>>>> am not even able to free the memory allocated in the structure.
>>>>> I need to be able to tell the lp_solve functions to interrupt
>>>>> themselves if I am going to support interrupts at all.
>>>>> I took a longer look at errors.c and it seems my solution should
>>>>> work as long as neither HAVE_AQUA nor Win32 are defined. Under
>>>>> the circumstances, I think that's the best I can do.
>>>>> Any suggestions for a UI independent way to check for interrupts
>>>>> would be appreciated.
>>>> Why not use the same code as R_CheckUserInterrupt but instead of
>>>> calling onintr, call your own interrupt routine?
>>>>> Thanks,
>>>>> Kjell
>>>>> On 15 mai 08, at 16:41, Prof Brian Ripley wrote:
>>>>>> How is R_interrupts_pending going to be set?
>>>>>> It is set in the interrupt handler for SIGINT, but that is not
>>>>>> the only way to indicate an interrupt, and it is not
>>>>>> necessarily available to users of GUIs and embedded R.
>>>>>> Without servicing the GUIs all interaction will be dead,
>>>>>> including sending an interrrupt from menus/buttons/keyboard.
>>>>>> See the comment in the code for R_CheckUserInterrupt.
>>>>>> On Thu, 15 May 2008, Kjell Konis wrote:
>>>>>>> Hello,
>>>>>>> I have some native code that I would like to allow users to
>>>>>>> interrupt. However, I would like to do it more gracefully than
>>>>>>> with R_CheckUserInterrupt(). The solution I came up with is to
>>>>>>> call the following abort function periodically - if it returns
>>>>>>> 1 then I clean up and return.
>>>>>>> int __WINAPI RlpSolveAbortFunction(lprec *lp, void *userhandle)
>>>>>>> {
>>>>>>> if(R_interrupts_pending)
>>>>>>> return(1);
>>>>>>> return(0);
>>>>>>> }
>>>>>>> This seems to work fine on Mac (sans Aqua) and Linux. Is this
>>>>>>> going to be portable? Also, is there anything else I need to
>>>>>>> do? For instance set R_interrupts_pending to 0 after I
>>>>>>> respond to it?
>>>>>>> Thanks.
>>>>>>> Kjell
>>>>>>> ______________________________________________
>>>>>>> R-devel at r-project.org mailing list
>>>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>>>> --
>>>>>> Brian D. Ripley, ripley at stats.ox.ac.uk
>>>>>> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
>>>>>> University of Oxford, Tel: +44 1865 272861 (self)
>>>>>> 1 South Parks Road, +44 1865 272866 (PA)
>>>>>> Oxford OX1 3TG, UK Fax: +44 1865 272595
>>>>> ______________________________________________
>>>>> R-devel at r-project.org mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>> --
>>>> Brian D. Ripley, ripley at stats.ox.ac.uk
>>>> Professor of Applied Statistics, http://www.stats.ox.ac.uk/
>>>> ~ripley/
>>>> University of Oxford, Tel: +44 1865 272861 (self)
>>>> 1 South Parks Road, +44 1865 272866 (PA)
>>>> Oxford OX1 3TG, UK Fax: +44 1865 272595
>>>
>>> ______________________________________________
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>> --
>> Luke Tierney
>> Chair, Statistics and Actuarial Science
>> Ralph E. Wareham Professor of Mathematical Sciences
>> University of Iowa Phone: 319-335-3386
>> Department of Statistics and Fax: 319-335-3017
>> Actuarial Science
>> 241 Schaeffer Hall email: luke at stat.uiowa.edu
>> Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
>
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