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Re: First experience using own baton

From: Stefan Küng <tortoisesvn_at_gmail.com>
Date: Tue, 04 Sep 2012 22:31:34 +0200

On 04.09.2012 13:05, Oto BREZINA wrote:
> I decided to try own baton implementation for file diff. Even I known
> your opinion, I still think it is worthy to try.
> Expected gain:
> - remove need of temporary file handling
> - speed increase (text is already divided into lines, no need to convert
> to UTF8 (from UTF16), no need access file system) I expected double the
> speed.
> - implementation of our own normalizing rules (EOLS(all we support),
> whitespaces, ....)
> - possibly less memory consumption
> I took diff_memory.c and tweak it to my needs, basically it means to use
> tokens from CFileTextLines.
> After I make it work (without normalizing for a moment) it runs a way
> slower then diff_file solution. 1.3 to almost 2 times slower.
> Do you have any idea why it that? My only guess is that baton code is
> too far from diff code, so we have cache misses. Maybe some windows
> protection while jumping to/from code boundary dll to main code?

I doubt that. Such problems wouldn't cause a two times slowdown.

> I have no idea why it can be that slower. I use already vector as base
> class as it is bit faster then deque on read.
> I will try to use original codes for diff_file in main code to see if it
> is implementation or some other issue.
> I also think about to use modified diff_memory - remade for wchar_t as
> we have whole file converted to UTF16 in memory in some load stages.
> For a moment only one of four gain is made.
> I found that you implemented SVNLineDiff.
> What is your experience with it ?

It works - it's used for the inline diff.

> Why did you implemented your own Adler32 methode?

Because the one in the svn lib is private and not exported.

> Why you and svn guys start Adler32 with 0, when according to
> http://en.wikipedia.org/wiki/Adler-32#The_algorithm A is initialized to
> 1? Shouldn't we start Adler32 with 1 as checksum?

No idea - I just copied the function.

I just noticed (build from saturday) that there's a serious problem with
editing: when saving edits and reloading, the diff is sometimes
completely different, i.e. it does not save what you've edited but
something else.
You can see that if you have "compare whitespaces" enabled.


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Received on 2012-09-04 22:31:52 CEST

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