[Freeciv-Dev] (PR#8876) CM cache1 is way too big

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=8876 >

The citizen management code's cache1 cache is much bigger than it needs 
to be.  This is because it uses a spatially inefficient index mechanism.

With n citizens to be places as citizens and m different citizen types, 
you really only need

   C(n + m - 1, m - 1)

different combinations (I could be off-by-one here).  With the current 
m==3 this is (n + 2) * (n + 1) / 2.

However the cache contains

   (n + 1) ^ (m - 1)

different elements.  Of course all the extra ones aren't valid positions 
and are unused.  With the current m==3 this is

   (n + 1) ^ 2

of course specialists that can't be used by the city shouldn't be 
included in the "m" here.  Currently this may include some citizens 
based on city size.  But this may be extended in future (some 
specialists may have tech_reqs, others may be obsoleted by new specialists).

jason