On 18.07.2012 14:31, Bart Visscher wrote:
Hi,
On Wed, Jul 18, 2012 at 10:31:13AM +0200, Klaas Freitag wrote:
For that, the best would be if the ownCloud WebDAV server would
provide another WebDAV property that returns the md5-sum of the file
or file list. That probably means that the md5 sum needs to be
calculated on every file change on the server and be stored in the
fs cache.
I think you could use the etag for that, this is a standard property in
WebDAV.
AFAIU Etags could help us here if the PUT of a new file to the server
would have an ETag in the response which could be stored on the client.
On subsequent sync runs, the Etag could be checked to see if it has
changed. Yet, currently I can neither see an etag in the PUT response
nor in a GET. That is probably because the getETag implementation in
lib/connector/sabre/file.php returns null. So that would still have to
be implemented.
For transfering big files, i have looked at the librsync
protocol/way. This uses a rolling checksum and a strong hash. The hash
is md4 which is implemented by php. The rolling checksum is not
implemented by php, I made a version in php, but this proved to be
slow (1 second/MB on a fast machine). There is a PECL extension, but i
think that as owncloud we should also have an alternative.
Yes, but that is another problem, right?
Is that doable? Who can help with that?
I we use the etag property we should calculate this when it is needed,
not when the file changes. File can change multiple times in between
etag requests.
Well, calculating an MD5 at least takes some time, so it would be better
to get that out of the DB rather than calculating it on request.
regards,
Klaas
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