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Re: [Monotone-devel] url schemes
Re: [Monotone-devel] url schemes
Mon, 24 Mar 2008 14:14:23 +0100
Mozilla-Thunderbird 18.104.22.168 (X11/20080109)
Derek Scherger wrote:
Xxdiff does work reasonably well to look over whitespace polluted diffs
if you turn off display of whitespace. ;)
Oh, thanks, I will give that a try.
that that's not the case where nuskool is supposed to be the winner.
I'm assuming that if this does work out it will replace netsync and it
just can't be slower and be successful imho.
I can see two workarounds to that: either partial pull (which will be
much easier to implement on top of nuskool), or automating the "full
repository download" hack, in case the target database is still empty.
However, if we can tweak nuskool to handle initial pulls equally good,
that would be even better, yes.
Yeah, the revision refinement phase is really quick. Side note: I'm not
100% sure it's correct yet. I do recall seeing a push saying that there
are X outbound revs while pull, with the databases reversed, had some
other number of inbound revs. We need to double check this.
Oh, really? Hm.. Well, I've started writing unit tests for gsync. Maybe
we should enhance those to be useful, i.e. test some random DAGs or
Oh, another note here. I purposely set things up in run_gsync_protocol
so that the client knows exactly which revisions are inbound and
outbound, thinking that we really want something like push/pull/sync
--check to list (but not transfer) revisions that will be transferred.
The mercurial equivalents are the incoming/outgoing commands.
Yeah, that would certainly be useful as well. Should be straight forward
to implement with nuskool. :-)
This may require a bit more information coming back in the descendants
response, including author/date/changelog/branch certs for example. The
thought of combining author/date/changelog/branch into one commit cert
crossed my mind here again. The current certs don't allow us to tie the
correct things together. Maybe we should start another branch to combine
these certs into a single commit cert.
That applies to the current http channel. Other channels might or
might not use JSON. Or maybe we even want to add different
content-types for http, i.e. return json or raw binary, depending the
http accept header.
Yeah, both ideas have crossed my mind as well.
I may just try having get_revision include all of the file data/delta
details as well, and see how big these get in the monotone database. If
we didn't first encode the json object as a string and subsequently
write it to the network we could just start writing bytes until we were
done and not have to hold them all in memory. However this causes
problems with trying to set the Content-Length header.
Yes, plus problems with dumb servers... (am I not annoying with that
topic, am I? :-) )
I'm not sure what
to think of issuing several requests (one for each file data/delta in a
revision, perhaps up to some limit). Actually, I don't think it would
help, because the server can only handle one request at a time afaict or
there will be multiple scgi processes running and there will be database
Right, however, normal (dumb?) http servers can perfectly well handle
multiple request, so this time, dumb servers don't look that dumb. ;-)
And even if the scgi server would serialize request to the database,
overall it would still reduce waits for network latency on avg, because
multiple requests could be issued concurrently.
So would a hand-optimized sha1 implementation. Would someone just write
one of these already! ;)
Uh.. isn't the botan provided one hand optimized enough? If not, let's
please tweak that, so other botan users can take advantage as well.
(The library-build branch should allow us to link against optimized
botan code, one day. That's one of the things we should really work on...)
I went with the fine-grained get/put request/response pairs so that
neither side would end up having to hold too many files in memory at
any one time. If we instead requested all file data/deltas for one
rev the number of round trips would be reduced but we'd end up having
to hold at least one copy (probably more) of the works in memory
which didn't seem so good. I'm open to suggestions. ;)
I don't think files necessarily need to be put together by revision -
that would be a rather useless collection for small changes. Instead,
we should be able to collect any number of files together - and defer
writing the revision until we have all of them.
I'm not really sure where you're going with this.
You were saying, that "if we requested all file data/deltas *for one
revision*" in one request, that would reduce round trips.
However, lots of revisions just change one file, so that optimization
wouldn't reduce round trips for those.
AFAICT, mercurial transfers so called changegroups, where they group
together file data/deltas across revisions - they simply don't care what
revision a file is in for those changegroups.
However, such a thing would not be compatible to dumb servers, so I
consider in an optimization, at best.
Agreed, however, I'm wondering how popular or useful scripted
pushing/pulling is going to be.
Yeah, that's hard to say. But with all the Web 2.0 hype... maybe we can
start a VCS 2.0 hype and get surprised by all the new applications built
on top of our API... :-)
When I first say the json format I
though that it might have been nice to have that rather than basic_io
but it probably didn't exist at the time basic_io was invented.
You mean, using JSON internally, as a revision/manifest/roster format?
Might save some space, but I find the basic_io more human readable, and
favor it for that reason.
Yeah, the base64 encoding/decoding of file content is another extra step
that shouldn't really be needed.
Yeah, json is not optimal in that respect.
How about other, more space efficient encodings, like Ascii85? There
must be something which encodes binary data in UTF-8 strings, no?
Something, that's also used for UTF-8 encoded XML CDATA. Such an
encoding must exist, otherwise I'm gonna write one.... (ehm, or probably
Or storing the revisions in the database as binary rather than text, but
I guess we don't actually use the revisions themselves that much do we.
Seems like a reasonable idea.
..ehm.. yeah, I had quite a debate with Nathaniel on this topic during
the last summit. Since then I didn't really dare to bring this idea up
His counter argument was, that rosters are cached data and it's nice to
be able to regenerate them. He was concerned about not being able to
change the rosters format.
And I can certainly see his point. Just recently, for
nvm.e.db-compaction, it looks like I've changed the rosters format
(didn't double check, yet, so I'm not quite sure) And it was nice to
just force a db regenerate_caches and be done, instead of having to
write a rosters format converter.
However, I still think dropping the revisions from the database would be
worthwhile - because it would not only reduce database size, but also
help reducing i/o bandwidth.
In general, I think it would be great if we had a few people working
together on all of these things, rather than one poor lonely soul on
each of them. You and Zack seem to have been doing a bit of this on the
compaction and encapsulation branches and I'm sure it's more fun and
produces better results that way.
Sure it is. And I'd say that we had some of that fun as well on nuskool.
I'd certainly like to continue that. However, spare time is pretty tight
sometimes... I just dedicated these easter days, instead of doing by
book-keeping. But I cannot defer that endlessly :-(
Re: [Monotone-devel] url schemes, Derek Scherger, 2008/03/22