Re: Command line way to prevent unbuffered?

[Jim K. <je...@kl...>]

Ethan Merritt wrote:
> On Monday 10 January 2005 10:46 pm, Ethan Merritt wrote:
>>> diff -u -r1.72 plot.c
>>> --- plot.c    25 Aug 2004 22:33:16 -0000    1.72
>>> +++ plot.c    11 Jan 2005 05:26:21 -0000
>>> @@ -422,7 +422,9 @@
>>>       * Do any non-X platforms suffer from the same problem?
>>>       * EAM - Jan 2004.
>>>       */
>>> -    setvbuf(stdin, (char *) NULL, _IONBF, 0);
>>> +    if (isatty(fileno(stdin))) {
>>> +        setvbuf(stdin, (char *) NULL, _IONBF, 0);
>>> +    }
>>>  #endif
>>
>> I see why you want this.  But speed is no good if the program
>> does not function properly, and previous experience showed that
>> unbuffering the input stream was needed for at least some 
>> implementations of piped input.
> 
> I have changed my mind.  The behavior is not likely to differ
> from user to user, only from one platform to another. So it should
> be a configuration option for building on that platform, not a
> run-time option on the command line.
> 
> How about we wrap the code as follows:
> 
> #ifndef UNBUFFERED_STDIN
>     setvbuf(stdin, (char *) NULL, _IONBF, 0);
> #endif
> 
> and you can provide a brief set of instructions for how to set
> this conditional compilation flag during the cygwin configuration setup.
> I have not used cygwin, so I don't know exactly how that is done.
> 
> It would be nice if you also checked that this doesn't interfere
> with correct execution of "pause" commands, however, since as I
> recall that was one of the original problems this was supposed to fix.
> For instance, please check that "mousevariables.dem" works properly with 
> buffered input under cygwin. 


The attached patch achieves the speedup and works
properly with mousevariables.dem.

The use of __CYGWIN__ makes it specific to that platform.

I suspect this would also help other platforms.

Please consider for upstream inclusion.

Thanks - Jim