[Freeciv-Dev] Re: CMA crash when choosing new govt (PR#1546)

[Raimar Falke <rf13@xxxxxxxxxxxxxxxxx>]

On Thu, Jun 27, 2002 at 12:30:21AM -0700, Per I Mathisen wrote:
> On 26 Jun 2002, Kenn Munro wrote:
> > The patch fixes the bug.. it is no longer possible to change government
> > while the client is still busy doing the start-of-turn stuff.
> >
> > But, you were correct in assuming that "other changes (tax rates for
> > example) may have such problems".
> ...
> > Probably not a *big* deal.. you can't end-turn when the tax dialog is
> > up, so the user would have to end-turn, then quickly Shift-T and change
> > the rate.
> 
> But even if you can't end turn, the turn can still end while you have that
> dialog up (due to timeout).
> 
> > I also got the same error for another city while disbandings units from
> > a city dialog box while between turns.  I suspect there may be many more
> > ways to cause such problems.  As they won't all be found/fixed before
> > release, there should be a mention in BUGS of bad things happening
> > sometimes when doing stuff while the client is between turns.
> >
> > And, what's the best way to fix them all?  Address them each as they are
> > found or not allow any user intervention until all turn stuff is
> > complete?
> 
> Why does this happen? I don't see any good reason why you shouldn't be
> able to change government while agents are processed, as the agent event
> is scheduled. Isn't there an underlying design flaw here?

First I want to thank Kenn for the testing.

Second I want to thank Per for accusing the architecture. This is
always a good way to get someone moving.

It turns out that the previous fix is just a band-aid (lazy me). And
the real fix is a one liner (call of clear_caches).

For the protocol here is the situation (enlarge your xterm a bit)
(this is a bit like
what-you-never-wanted-to-know-about-agents-and-network-interaction
(and also the reason why server side AI is a lot easier)):

   CLIENT                                        SERVER
  revolution
                                       (activities which doesn't matter here)
  send turn done
                                       end turn activities
                                         update the player info
  new player info
  popup government dialog
  user choose democracy
                                         [ still in the end turn activities]
                                         refreshing all cities and sending them 
to the client
  new city info for city X
    CMA calculated with government ANARCHY
    CMA have to change the city X
    CMA send requests
                                      finish end turn activities
                                      Democracy request:
                                        government set to Democracy
                                        send player info
                                        refreshing all cities and sending them 
to the client
                                      CMA request for city X
                                        send new city_info for X USING DEMOCRACY
      new player info with Democracy
      city_infos:
        cities are updated
        cities are queue for the agents
    city_info for X which doesn't 
     match the calculated one. Previously 
     this gone BOOM. Now it clears the 
     cache and recalculates city X 
     with Democracy.
    CMA calculated with government Democracy
    CMA have to change the city X
    CMA send requests
                                      CMA request for city X
                                        send new city_info for X using Democracy
    city_info for X which match
  CMA action for city X finished
  agents.c will search for other 
   queued cities which have changed and
   need verification that there are still 
   optimal
      o
      o
      o

So Kenn can you please test this against the rate changes "attack"?

        Raimar

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1546_fix1.diff
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