R devel - Aug 2013 - 2 questions about signal & broken connection in R

Hi, all,

I have 2 questions about signal handling in R. Would you pls help give me
some suggestions? Many thanks!

[How to block the signal in one R function]:
If one R function hopes to be running without interrupting, how can we
avoid this?
To be more specific, for one R function "func1", it will do a loop to
send
messages to another R process, and receive responses from peers. How can we
avoid users interrupt this function by pressing "Ctrl+C", so that it
can
finish normally, without messing up the message protocol? Are there any way
to block signal handling within the function?

[why writing to one broken connection for the 3rd time will hang, instead
of getting exceptions]:
Such as, there is one broken socket connection (in blocking mode), which is
closed by peer by calling "close(conn)".
The 1st write will return. The 2nd write will get an exception. The 3rd
write will hang there forever.
How can users always get an exception or other error messages when writing
to a broken connection, instead of possibly hanging there?
> writeBin(as.integer(1), con, endian="big");
> writeBin(as.integer(1), con, endian="big");
Error in writeBin(as.integer(1), con, endian = "big") :
  ignoring SIGPIPE signal
> writeBin(as.integer(1), con, endian="big");  ----- hanging

====================
Rong "Jessica", Li
Platform Symphony TET, CSTL, IBM Systems &Technology Group, Development
Tel:86-10-82451010  Email:ronglli@cn.ibm.com
	[[alternative HTML version deleted]]

You seem to be assuming that Ctrl-C is the way to interrupt an R session 
and that it sends a signal.  Neither are true, in general, nor is there 
a general way to turn off interruptibility from the R console.

You have not followed the posting guide and it may be that you are only 
interested in some particular R setup -- which you did not tell us about.

If you want to run code so that it is not interruptible from a console, 
do not run it from a console ....

On 14/08/2013 11:30, Rong lI Li wrote:
>
>
> Hi, all,
>
> I have 2 questions about signal handling in R. Would you pls help give me
> some suggestions? Many thanks!
>
> [How to block the signal in one R function]:
> If one R function hopes to be running without interrupting, how can we
> avoid this?
> To be more specific, for one R function "func1", it will do a
loop to send
> messages to another R process, and receive responses from peers. How can we
> avoid users interrupt this function by pressing "Ctrl+C", so that
it can
> finish normally, without messing up the message protocol? Are there any way
> to block signal handling within the function?
>
> [why writing to one broken connection for the 3rd time will hang, instead
> of getting exceptions]:
> Such as, there is one broken socket connection (in blocking mode), which is
> closed by peer by calling "close(conn)".
> The 1st write will return. The 2nd write will get an exception. The 3rd
> write will hang there forever.
> How can users always get an exception or other error messages when writing
> to a broken connection, instead of possibly hanging there?
>
>> writeBin(as.integer(1), con, endian="big");
>> writeBin(as.integer(1), con, endian="big");
> Error in writeBin(as.integer(1), con, endian = "big") :
>    ignoring SIGPIPE signal
>> writeBin(as.integer(1), con, endian="big");  ----- hanging
>
>
> ====================>
> Rong "Jessica", Li
> Platform Symphony TET, CSTL, IBM Systems &Technology Group, Development
> Tel:86-10-82451010  Email:ronglli at cn.ibm.com
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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