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From David Fisher <dfis...@jmlafferty.com>
Subject Re: Lower memory POIFS
Date Wed, 29 Dec 2010 03:45:17 GMT
Cheers! Quite an accomplishment!

Dave

On Dec 28, 2010, at 7:41 PM, Nick Burch wrote:

> On Mon, 13 Dec 2010, Nick Burch wrote:
>> Just a heads-up that I'm planning to spending some time while I'm off over Christmas
working on a lower memory POIFS implementation. The idea is to have it load blocks on demand,
in disk instead of logical order, rather than the current code which loads everything and
sorts before use.
>> 
>> Initially I'm aiming for enough support to be able to read the directory listing,
and read streams. I'm not intending to support write, but I do aim to leave extension hooks
in place so it can be added later if anyone wants to! Performance wise, I suspect it'll be
faster to load, but slower to read streams (due to disk seeks)
> 
> I think we're now largely there with this, with all the code in svn trunk. It still needs
to be documented, and not all the POIDocument implementations can work with it for read (write
isn't supported yet)
> 
> However, running HPSFPropertiesExtractor against a 9mb file:
> * POIFSFileSystem - minimum Xmx 12mb, average time 250ms
> * NPOIFSFileSystem - minimum Xmx 2mb, average time 190ms
> So, the new code is both lower memory and faster, which seems a result!
> 
> Once write support is done, and tested, I'd lean towards making NPOIFS an option for
one release, then rename POIFS to OPOIFS and make NPOIFS the new default. More on that when
they're feature compatible though!
> 
> Nick
> 
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