Re: [SCRIPT] cg-rpush & locking

From: Matthias Urlichs <smurf@smurf.noris.de>
Date: Jun 2, 2005, 07:14 UTC
Message-ID: <20050602071453.GA16616@kiste.smurf.noris.de>
In-Reply-To: <Pine.LNX.4.21.0506020223570.30848-100000@iabervon.org>

Hi,

Daniel Barkalow:

Show 8 quoted lines

> If the lock is only to protect against someone else modifying HEAD after
> we've checked that it is our starting point and before we modify it,
> there's no reason not to hold the lock while pushing; it wouldn't block
> anything other than someone doing a quick push in the middle of our long
> one, and thereby causing us to dump a lot of useless objects on the
> server (which will become obsolete as we will need to do the merge and
> push a different version).
>

The objects we push aren't going to be obsolete. The server needs them anyway, because our HEAD refers to them.

What if the connection dies in the middle of a push? You then sit there waiting for it, and the lock, to time out. OTOH, an atomic cmpxchg on the server can't block and can't timeout.

Show 5 quoted lines

> you want to have the
> client watch for the resolution of the other transfer one way or the
> other, since you're in the current state precisely because you lost on
> getting the lock and now definitely need the next version.
>

I disagree. Given that you need to wait for the upload to finish anyway (whether you know it or not ;-) it makes sense to spend the time actually uploading -- upload speed is frequently lower than download for individuals.

-- 
Matthias Urlichs   |   {M:U} IT Design @ m-u-it.de   |  smurf@smurf.noris.de
Disclaimer: The quote was selected randomly. Really. | http://smurf.noris.de
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