Re: [Wesnoth-dev] C++ streams and VC++6

[David White]

Guillaume Melquiond wrote:

> On 4/27/05, David White wrote:
>  
>
> > In 0.9.0, we switched to using istreams to read files, instead of using
> > the C API.
> >
> > Unfortunately it seems the istreams implementation that ships with VC++6
> > is very slow. It can take a very long time for an uncached game to load
> > a campaign -- up to a minute on my 2Ghz machine, and some users seem to
> > report it taking many minutes.
> >    
>
> On my 600MHz machine and GCC 3.3, it takes six seconds to create the
> cache for HttT (it would be even faster if I was not using a
> zip-install Wesnoth). This it is the delay for the "loading scenario"
> to appear after "no valid cache found" was displayed. Once the cache
> is built, this step takes less than one second.
>
> And then, it takes ages to display HttT map (the time necessary to
> initialize the scenario): 12 seconds. This is huge, it also appeared
> at the time of 0.9.0, and the main problem lies within: 
> (--log-info=all)
>
>        BEGIN: terrain_builder::parse_config
>        END: terrain_builder::parse_config (took 10387ms)
>
> and there is no stream at all in the related functions!
>
> So before discussing the stream matter any further, I would like to be
> sure that the many minutes the users experience with the VC6 build are
> really during preprocessing / tokenizing / parsing.
>  
On my 2Ghz Windows machine when there is no cache present, we get,

BEGIN: read_game_cfg
no valid cache found. Writing cache to 
'f:/wesnoth/userdata/cache/game.cfg-cache-v0.9.1-CAMPAIGN_HEIR_TO_THE_THRONE-MEDIUM-NORMAL'
 BEGIN: preprocessing file...
info general: Streaming data/game.cfg for reading.
info general: Streaming data/themes/default.cfg for reading.
....many more file streaming lines omitted
 END: preprocessing file... (took 40184ms)
info general: Streaming 
f:/wesnoth/userdata/cache/game.cfg-cache-v0.9.1-CAMPAIGN_HEIR_TO_THE_THRONE-MEDIUM-NORMAL 
for writing.
info general: Streaming 
f:/wesnoth/userdata/cache/game.cfg-cache-v0.9.1-CAMPAIGN_HEIR_TO_THE_THRONE-MEDIUM-NORMAL.checksum 
for writing.
END: read_game_cfg (took 41047ms)
loading scenario: 'The_Elves_Besieged'
...
BEGIN: terrain_builder::parse_config
END: terrain_builder::parse_config (took 1112ms)
BEGIN: terrain_builder::parse_config
END: terrain_builder::parse_config (took 0ms)
BEGIN: terrain_builder::build_terrains
END: terrain_builder::build_terrains (took 60ms)

So, as we can see, the 'insane' amount of time takes place in 
preprocessing, and I assume, when reading files. When I have time I will 
try replacing the streams with C-style I/O, and see how much faster it is.

terrain_builder::parse_config may be a good place to look at later to 
tweak load times, but isn't the cause of the incredibly long load times 
on Windows.

David