terminate the solver process on stop

[temyurchenko]

otherwise the solver can hang in the background a very long time

[yav]

I can see some situations where you just want to kill the solver, but it's probably nice to have a proper exit option too. So I'd suggest we do the following:

1. replace the filed stop :: IO ExitCode with a different one stopMaybeForce :: Bool -> IO ExitCode
2. define stopMaybeForce force = if force then terminate else old_beahvior
3. add a function stop :: IO ExitCode defined as stopMaybeFroce False
4. add a new function forceStop :: IO ExitCode defined as stopMaybeForce True

What do you think?

[temyurchenko]

That makes sense, will do. In that case, it would even be possible to give the solver some timeout to stop gracefully and kill it if it doesn't.

Is there any reason to have specifically stopMaybeForce rather than just stop and forceStop?

[yav]

Good point, probably simpler to just add forceStop as an extra method.

[jwaldmann]

I can see some situations where you just want to kill the solver,

I also do: several solver instances are running concurrently (on different constraint systems - that are equivalent w.r.t. my application). I just want the first solution - and kill all other solver instances.

[temyurchenko]

Done. If you don't like the terminate/exit naming, I can change it to stop/forceStop.

[yav]

Hi, thanks for the changes. I think it's a good idea to keep the old one as stop to avoid breaking existing code. I don't mind about the name of the new function (the one that just kills the process), but perhaps stop/forceStop is more obvious than stop/terminate

[temyurchenko]

Hi, thanks for the changes. I think it's a good idea to keep the old one as stop to avoid breaking existing code. I don't mind about the name of the new function (the one that just kills the process), but perhaps stop/forceStop is more obvious than stop/terminate

Definitely, what was I thinking