[Freeciv-Dev] Re: Unused field in move_cost_map removed. (PR#965)

[rf13@xxxxxxxxxxxxxxxxxxxxxx]

On Tue, Sep 18, 2001 at 12:39:32PM +0100, Gregory Berkolaiko wrote:
> I did some experimenting with the returned field of move_cost_map (aka
> warmap),
> http://www.freeciv.org/lxr/source/server/gotohand.h?v=cvs#L38
> 
> It's intended use was to indicate to the warmap generator that a location
> has already been processed.  However, by virtue of Dijkstra's algorithm,
> such an occurence is quite rare.  This is probably the reason why it is
> not quite used (although initialised) in the currecnt code.  

I looks like I miss something here: returned is malloc'ed, memset'ed
and tested but NEVER set. So the this variable is useless. If you also
come to this conclusion I don't understand why you made test runs?

> I tried following things: check for "returned" disabled (that's current
> code), 

Ok.

> check enabled

So what you think is the correct usage of this field?

> and also plain removing all mentions of this
> "returned" field.  The savegames from the runs were identical in all
> cases 

> (expected)

You mention above that such "occurence is quite rare".

> . The results of timing the test runs were:

> If I interpret the results correctly (looking at u time), enabling the
> check sometimes gives an improvement; 
> removal of the field gives stable although little improvement, it also
> reduces volume of the code and memory used, so I suggest that it should
> be applied to CVS asap.

In its current form it is useless. I also vote for removing. (Mhh this
is the second code construct in server/gotohand.[ch] which has no
effect).

        Raimar

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