edit_file patch

[John Berthels]

Hi,

Sorry to follow-up my own post, but we're keen to use MogileFS in our
environment and have a need for some level of file editing support.
We're willing and able to maintain our patches outside the main tree
but would obviously prefer to try and merge this it upstream, since
this reduces our ongoing merge effort and makes the functionality
available for others.

I'd be grateful if someone could offer an opinion on whether this
functionality might be acceptable to MogileFS in some form or other
and if so, whether the current approach is going in the right
direction or should perhaps be reworked.


To recap, we've added an edit_file command to the protocol which
breaks off a replica and registers it as a tempfile with the same key,
so when the tempfile gets a create_close, the old replicas are removed
and the new file replicates out (this is existing functionality in
create_close).

There is an outstanding issue of what should happen with an edit_file
on a key with a replication count of 1, currently it steals that copy
which may not be desirable (and a silly bug in
MogileFS::ClientHTTPFile::READ in the patch I previously sent,
corrected copy available on request).

regards,

jb