[Freeciv-Dev] Re: RFD: Savegames and autogames

[Jason Dorje Short <jdorje@xxxxxxxxxxxx>]

Christian Knoke wrote:
> On Fri, Dec 24, 2004 at 04:17:39PM +0000, Per Inge Mathisen wrote:
>
> > Opinions?
> - Test mode for savegames w/ AI data
Hmm.

> - Recalculate the AI every turn from the data that is saved in savegames
>   anyway, so you don't need to save it.
The problem is more complicated than that (or than PR#436 indicates). 
If you calculate settler want every 10 turns then if there's a saved 
game in between, the only way to get the same results is to save the 
entire cached settler map.  This is possible but it may make the 
savegame large.  The problem is there's no real limit to how much cached 
data the AI may build.  And even if it's only used on the turn it's 
created on (if it's recalculated each turn) you still have to save it 
because savegames happen mid-turn (actually if you calculate the data 
during the end-turn you can be assured it will still be valid for the 
next begin-turn - but this doesn't help if your cache remains around or 
multiple turns).
This problem becomes worse if we have a multithreaded or asynchronous AI 
that continues running during the human players' turn.  Then a save can 
happen even in the middle of some AI calculations so even data that is 
cached and used on the same turn cannot be counted on.
In summary this may not be solvable.  But then PR#436 was only a pipe 
dream anyway.  Yet I do wonder how other games seem to manage this so 
easily.
jason