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Re: Eliminating multiple file-reads of text-base on updated targets

From: Peter N. Lundblad <peter_at_famlundblad.se>
Date: 2005-12-06 10:21:32 CET

On Tue, 6 Dec 2005, Erik Huelsmann wrote:

> I've found an optimization which would fit nicely in the 1.4
>'libsvn_wc optimizing release': libsvn_wc calls svn_io_file_checksum
>on files it just read or wrote - meaning it reads them again to
>calculate the checksum.

Do you know how much this costs performance-wise? Yes, it might be a
reasonable optimization, but it would be good to have the whole picture if
possible.

>- creating an svn_stream_checksummed, like svn_subst_stream_translated.
>- let the stream raise an error on close if the stream checksum
>doesn't match a given checksum value (with an error message text
>passed to it on creation)

Would it be better to just let the stream provide the checksum and let the
caller take care of the error handling itself? I see this passing of
error messages down the calls as a little ugly.

>- create svn_stream_checksummed_get_sum() to retrieve the checksum
>from the checksummed stream

Just provide a pointer where to store the checksum on close instead? The
function above wouldn't be type-safe, would it?

BTW, this is the big part of issue #1882.

Regards,
//Peter

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Received on Tue Dec 6 10:22:21 2005

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