Re: [Discuss-gnuradio] Possible diagnosis for issue 520, hier_block2::disconnect_all() misbehavior

[Tom Rondeau]

On Sat, Aug 17, 2013 at 12:33 PM, Kevin Reid <address@hidden> wrote:
> (I would have sent this as a comment on the issue tracker, but creating an 
> account didn't seem to give me permission to comment.)

See this in the FAQ for posting:

http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#How-can-I-post-on-this-wiki-use-the-bug-tracker

I have added you to the GNU Radio project so you can post now.

> I've been using GNU Radio (strictly via Python) and met what seems to be the 
> already-reported issue <http://gnuradio.org/redmine/issues/520>, where a 
> hier_block2 will misbehave after calling disconnect_all().
>
> Specifically, according to the exceptions seen from Python, it forgets that 
> it has any inputs or outputs and rejects attempts to connect to them; for 
> example, "output port 0 out of range for throttle(2)" resulting from 
> self.connect(throttle, self).
>
> I took a look at the code, and I found this suspicious bit in 
> hier_block2_detail.cc:
>
>   void
>   hier_block2_detail::disconnect_all()
>   {
>     d_fg->clear();
>     d_blocks.clear();
>     d_inputs.clear();
>     d_outputs.clear();
>   }
>
> I have very little C++ experience, but if I understand correctly, the last 
> two lines will cause the input and output port vectors to have length 0, 
> which would explain the observed behavior. There does not seem to be any code 
> which increases the size of the vectors again.
>
> If this is so, the fix would be to reset each element to the unset value 
> individually rather than removing elements. (I don't know how to write that 
> in idiomatic C++.)
>
> I hope someone who has a working GNU Radio development environment (I've 
> tried and failed, which is an unrelated problem) can try this fix.
>
> --
> Kevin Reid                                  <http://switchb.org/kpreid/>

This is really good information. Johnathan and I will look it over and
discuss it.

Thanks!

-- 
Tom
Visit us at GRCon13 Oct. 1 - 4
http://www.trondeau.com/grcon13