Re: Fwd: Sean Rivera Progress report 13/17

[sean rivera <sean.au.rivera () gmail com>]

> These are good tests to run. It looks like you're making progress.
>
> delay has type int, so I'm confused by what you're saying about delay <=
> 1.
> Does that mean you have tried, for example, delay = 0.5? Isn't the
> compiler rounding that to an int? It seems the only reasonable values to
> test are 1 and 0.

Delay might have type int, however the --delay flag for nping defaults
to seconds. Thus when I say that I set delay to 1 I actually set the
delay variable to 1000. That is what I meant by testing delay <= 1.

> It will probably help your debugging to track nsock_event_ids. These are
> just long ints. An nsock_event_id is returned, for example, from
> nsock_timer_create. Print out that id, and then add some debugging code
> to print the id in nping_event_handler. Then you can surely match up
> event creation and deletion.
>
> You can also get tons of Nsock debugging output by increasing the value
> given to nsp_settrace in nping/ProbeMode.cc.

Alright, I will track those down.

> > > From my testing so far I think the race condition is a combo of the
> >
> > "nsock_pcap_read_packet(nsp, pcap_nsi, nping_event_handler,
> > o.getDelay(),
> > NULL);"
> >
> > scheduled event and the
> >
> > "nsock_timer_create(nsp, nping_event_handler, 1, &pkts2send[pc]);"
> >
> > that is called only on the first time.
> >
> > I am also pretty sure that it is because of that hard coded 1 for time
> > out.
> > (Every other time it is o.getDelay() but I'll need to test that.
>
> The constant timeout of 1 ms might have something to do with it. It
> seems that instead of directly sending the first probe, we schedule a
> timer with a negligible timeout, which does the actual send when it
> expires? I guess that is for uniformity with how the subsequent probes
> are sent. But maybe we should just send the first probe? Or use a
> timeout of 0? (But check if a timeout of 0 has a special meaning first.)

I've checked timeout of 0 which does not have any special effect. It
also doesn't really effect the first probe sent at all.

> David Fifield
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--

~Sean Rivera
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