On 5/2/10 8:56 AM, Philipp Marek wrote:
Hello Stefan!
The idea is the following: ra_local (and possibly others)
are "reliable" in that they won't corrupt transmission.
For now, this implies that we don't need to checksum
the data again. There might be more shortcuts that
can be taken in the future.
...
With all other patches applied, this saves 15% runtime
in 'svn export file://'. However, rev'ing svn_delta_editor_t
seems only be feasible in context of 'editor v2'.
I understand your point, and 15% sound very interesting.
But I'd like to note that even for local operations it's a nice feature to
avoid data
corruption via software bugs (off-by-one and similar), and over LAN it's nice
to have,
too (eg. because of bugs in switches and routers, see eg.
http://www.cs.pitt.edu/~kyoungsoo/cs2520/papers/CRC_TCP_Checksum.pdf).
As the WAN (Internet) uses the same protocols as a LAN (TCP, IP) following that
argument
would mean that the checksum is informational only, and doesn't need to be
checked.
So I'd propose that this would be configurable for the paranoid people (like
me, maybe ;-).
Given the size of the patch, reving of the API and that I like the checksum to
always be done, I would just have svn always perform the checksums.
Blair
