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Re: [PATCH] Simplify and optimize RA-svn's string marshalling

From: Julian Foad <julian.foad_at_wandisco.com>
Date: Mon, 06 Jun 2011 12:49:59 +0100

> On 03.06.2011 10:52, Julian Foad wrote:
> > Hi Stefan2 and others.
> >
> > This patch simplifies code in RA-svn/marshal.c by using a single code
> > path to read both short and long strings efficiently. Using a single
> > code path is beneficial for test coverage.
> >
> > It is an alternative to r1028352 which merged r985606 and r1028092 from
> > the performance branch.
> >
> > I have run the test suite over RA-svn (with BDB) but haven't done any
> > more testing than that. It's just something I noticed while looking at
> > that code, it's not solving a problem I've noticed or anything like
> > that. By inspection I believe it is more efficient than
> > read_long_string() was, and unchanged for short strings, but if you're
> > able to do any performance analysis on it, that would be great.

Daniel, thanks for your detailed review comments. I'll address them if
we decide the patch is useful. But Stefan has another idea.

Stefan Fuhrmann wrote:
> Thanks for the patch. Currently, I 'm in the process
> of moving and won't find time for a detailed review
> and test until sometime next week.
> But maybe the right solution would be replacing
> read_long_string() with a simple error return. That
> is the only way to limit memory consumption on the
> server side. If the protocol has been we implemented
> correctly, no string should be longer than about 100k
> (a svndiff window). So, rejecting everything above,
> say, 16M should be fine.

Sounds good. If we can set some maximum length above which the code
should throw an error, then I offer the patch attached below instead. I
need to rely on others to confirm that approach as I don't know that to
be true.

(The patch as attached here is made ignoring white space, so applying it
will give wrong indentation. And I'd want to change the name of the max
length constant as well.)

- Julian

Received on 2011-06-06 13:50:38 CEST

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