Non working cache when session_settings::disable_os_cache

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I set in torrent session:
disk_io_write_mode = session_settings::disable_os_cache;
disk_io_read_mode = session_settings::disable_os_cache;

because when caching files libtorrent use >2GB of RAM.
But with this settings caching non working. When i add new torrent(files 
already exist) whith torrent_info:

.storage_mode = storage_mode_sparse;
.auto_managed = false;
.paused = true;

Then i started torrent and torrent state changes in the following 
sequence(alert->message()):
1) resumed 
2) state changed to: checking (q) 
3) state changed to: checking 
4) state changed to: checking (q) 
5) paused 
6) resumed 
7) state changed to: checking 
8) state changed to: checking (q) 
9) paused 

And caching does not occur.

PS: I tested this in 0.15.7 ,0.15.8 ,RC_0_15 branch in Windows 7 64bit

Original issue reported on code.google.com by Lacro...@gmail.com on 3 Oct 2011 at 6:52