[crossfire] Map cache

[tchize]

Le Vendredi 26 Août 2005 01:45, Brendan Lally a écrit :
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      On 8/25/05, Anton Oussik <
      
      antonoussik at gmail.com
      
      > wrote:
     
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      > A solution I propose is to pre-load large maps and keep them around in
     
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      > memory in case they are needed. 
     
     
quite difficult to implement :)

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      Depends what you mean by pre-load. It might be possible to have the
     
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      server check each map when it loads, and then load all maps on exits
     
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      leading of from that map in an independent thread.
     
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      Of course this requires that the map loading be thread-safe, and I'm
     
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      fairly sure it isn't.
     
     
No it isn't as is the whole code of server.

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      An alternitive (which might be easier) would be to have a seperate map
     
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      loading thread at all times, and when a player enters an exit, not
     
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      change their map to the new one, but instead place them in 'limbo' if
     
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      the map isn't loaded (a unique map which is 1x1 and has no objects.
     
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      Then the player object would need to check every tick to see if their
     
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      map is ready. This still poses some problems with what to do with the
     
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      command queue, if a player has hit multiple arrow keys, should they be
     
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      discarded?
     
     
This isn't as simple, whole server code is thread unsafe, this mean
if you load map in a separate thread you will break about all likned lsits used in
server (objet pool, live objet lists, map lists, shared strings, and static 
variables used in some functions).

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      The other approach is to simply say that all the world maps put
     
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      together are fairly small, compared to the amount of memory many
     
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      servers have these days (and this is increasingly more and more true),
     
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      so it would be possible to just load all maps at start up, and keep
     
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      them loaded until they reset.
     
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There are 30x30 world maps
each of them is 50x50 in size
this makes 2.250.000 objects just for the ground objets


I see 2 problems. 

First, each of the objects weighting 0.5k minimum (supposing all pointer in object structure
points to null or common structures) we reach a total of 1098Megs used for background!
(need to hack server to get a real value)

Second, if my memory is still working well, this mean a linked list of 2.250.000 live objects
in server, list which is checked on a regular basis to see if objects have some turns to play.
This will slow down main server loop like hell.


Perhaps a bit of work would be first to identify where in the loading code, it take time to load big maps
using a profiler tool and then we can fix the real cause.


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