Behavior of --checksum, suggestion

Wayne Davison wayned at
Tue Jun 7 21:09:20 GMT 2005

On Tue, Jun 07, 2005 at 04:46:43PM -0400, Moshe Jacobson wrote:
> Is this something that would be hard to implement?

Yes, it would be rather awkward in the current protocol.  The way things
currently work, the receiving side needs to have all relevant info
already available in order to decide what files to send.  One possible
solution would be to add an extra "phase" prior to the file-transfer
phase (before the receiving side forks) where the receiver makes a pass
through the files and requests checksums for files that might need to be
transferred, and then proceeds on to the normal checksum-sending phase
(after forking) but with an optimization that allows it to avoid calling
stat() on all the files all over again (it would flag changed files,
required dirs, etc. during the earlier checksum phase).

So, that would be quite a big change, which probably means that it won't
happen -- at least, not in the current rsync (hopefully a future,
improved-protocol rsync will be more flexible in this regard, and it
would sure be nice to get around to working on it again before too


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