[Flightgear-devel] Issue 717: Disabling advanced weather crashes the sim

[Renk T. <tho...@jy...>]

Hooray alerted me to that one, and I would like to ask a few opinions on what to do and offer my own thoughts.

> *What steps will reproduce the problem?*
> 1.F10-Environment-Weather-Advanced Weather
> 2.Select METAR
> 3.Return to Basic weather

> *What is the expected output? What do you see instead?*
> Should still  be able to see METAR string for information, it's now showing 'Disabled'  

>From my perspective, switching between GUIs runtime and trying to mix features is problematic input in the first place. My inclination is if this needs to be hardened against problematic input  to treat the usage of the '-> Basic Weather' button as intention to leave Advanced Weather and just add a call to local_weather.clear_all(); to the code of the button which ends Advanced Weather when ending its GUI. That would leave Basic Weather still in disabled state though, so to go beyond I would need to save the state of Basic Weather at startup of Advanced Weather and write these parameters back when ending it. 

But where should the METAR string be? My idea was that you can get it in-sim via the radio, or if you want to cheat there's always the property browser to look it up. Displaying it on the Advanced Weather GUI as well is also not really a problem if that's what people think should be done. Any opinions?

> Also, after selecting 'Advanced Weather' then Shift-Esc restarting, clouds flash 
> repeatedly and then segfaults .. only when Shift-Esc after selecting Advanced wetather

Well, yes - a restart implicitly starts up Basic Weather again without terminating Advanced Weather and results in a fight between systems. 

Again, probably the best solution is to end Advanced Weather for good on restart (if anyone can tell me what property to tie the listener to?) because it's impossible to guess the cause for the restart - a restart at the same location would allow to keep the whole calculated cloud configuration and just leave it running and not restart Basic Weather, a restart at a different location however needs a lot of re-computation.

A problem in practice might be that Advanced Weather has some long-running loops with a timer of ~ 5 sec for things which only need to be checked now and then, so it doesn't die immediately, the loops expire only after they've been called one more time. Also, repeated 'add-cloud()' calls are apparently buffered and continue to be executed even after stopping the whole Nasal code.  

> To get the segfault I have to select Metar Live Data as above, go to Advanced Weather, select OK
> twice, get the message about Advanced Weather already enabled, select Clear/End, then 
> re-open advanced weather and select OK.

I just tried that one, but I didn't get the segfault, the system behaved as expected for me. I suspect there may be a timing issue involved - clouds from the previous call are still buffered somewhere and not yet in the scene, only clouds which are in the scene are deleted when the clear_all is executed, deleting clouds also isn't instantaneous, new clouds from the next call arrive with overlapping parameters - so I'd be interested if this occurs dependent on the coverage (I had a METAR with very few clouds) and if it depends on METAR at all and if it helps to wait 10 seconds between every operation. I do know that if I try hard, I can click the GUI faster than the system can add and remove clouds and produce inconsistent configurations.

All in all, I suspect that one may have more to do with the internal structure of add-cloud and remove-cloud than with the Nasal part of the operation.

* Thorsten