Re: fhpd vs RuntimeExceptions

[Andrew Cagney <cagney@redhat.com>]

Mark,

from the call; what about:
  CLI.printError(String)
and/or/...
  CLI.printError(Exception)
the "logic" deciding what to do with the exception; for instance if 
Exception.getMessage() is null/empty then things are bad; dump the 
back-trace; but otherwise just print the message (That should cover null 
pointer exceptions).

Andrew

Mark Wielaard wrote:
> We quickly went over this on the meeting just now.
> Just a summary to see if I got it all.
>
> On Wed, 2007-11-14 at 09:44 -0500, Andrew Cagney wrote:
>   
>> Mark Wielaard wrote:
>>     
>>> While investigating some bugs I noticed that the fhpd sometimes swallows
>>> the RuntimeExceptions from the core (and there I thought all was
>>> fine...).
>>>       
>> Just fyi, broadly the message stuff, at least for normal output, is 
>> going away.
>>
>> The reason is that the cli alternates between using addMessage and 
>> PrintWriter.print(...) for normal out; so I've been migrating stuff to 
>> just do PrintWriter.print.  But this leaves us still needing a way to 
>> consistently report errors.
>>     
>
> OK, good to know, I had only seen the Message variants in the code that
> I looked at. The (add)Message stuff had one benefit that it concentrated
> the generation of Messages so you can easily capture any exception
> causes, which may patch added. When using "raw" Printwriter calls you
> would need some way to capture and then report the errors indeed.
>
>   
>>>  This makes debugging the fhpd itself a little hard. I added a
>>> possible exception cause to the Message class and while I was at it
>>> added checks to make sure we don't present the user with an empty or
>>> null message (which is very uninformative). Currently we always print
>>> these possible exception causes when they are attached to a Message in
>>> CLI.flushMessages().
>>>       
>> We were printing both the error and the stack, that looked terrible (the 
>> number of times an exception occurs for legitimated reasons is 
>> surprising); so they were turned off.  Did this turn them back on?
>>     
>
> The cases I looked at were things like:
> http://sourceware.org/bugzilla/show_bug.cgi?id=5286
> http://sourceware.org/bugzilla/show_bug.cgi?id=5267
> Where there was an internal RuntimeException without a message so you
> would just see Error: null or Error: "" without any extra info.
>
> In those cases when you have an internal RuntimeException you now attach
> a exception cause to the message (and currently always print it, but
> that can certainly be made optional - either with a command line option
> to fhpd when started up or by setting some internal variable - see help
> set).
>
> The main problem seems to be how to categorize RuntimeExceptions.
> Currently we are mixing internal ones, that should never occur and when
> they bubble up to the fhpd CLI level should really be reported and
> "expected" RuntimeExceptions that "mean" something at the fphd level and
> for which only the message might make sense.
>
> Cheers,
>
> Mark
>
>