From: Junio C Hamano <gitster@pobox•com>
To: Stefan Beller <sbeller@google•com>
Cc: mhagger@alum•mit.edu, git@vger•kernel.org
Subject: Re: [RFC] Introducing different handling for small/large transactions
Date: Thu, 15 Jan 2015 15:34:19 -0800 [thread overview]
Message-ID: <xmqqppaf4o04.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <1421361371-30221-1-git-send-email-sbeller@google.com> (Stefan Beller's message of "Thu, 15 Jan 2015 14:36:11 -0800")
Stefan Beller <sbeller@google•com> writes:
> In ref_transaction_commit
> * commit the .lock file to its destination
> * in case this is a deletion:
> * remove the loose ref
> * and repack the packed refs file if necessary
Don't you need to repack and then remove the loose one, though?
Otherwise you would expose a stale packed ref in the middle to the
other readers, no?
> The larger transactions would be handled differently by relying
> on the packed refs file:
> In ref_transaction_update:
> * detect if we transition to a large transaction
> (by having more than one entry in transaction->updates)
> if so:
> * Pack all currently existing refs into the packed
> refs file, commit the packed refs file and delete
> all loose refs. This will avoid (d/f) conflicts.
>
> * Keep the packed-refs file locked and move the first
> transaction update into the packed-refs.lock file
>
> * Any update(delete, create, update) is put into the locked
> packed refs file.
I am not sure if you mean (a) keep updates only in-core, to be
flushed at the commit time, or (b) each and every update in the
large transaction results in rewriting the entire packed-refs.lock
file, only to be renamed to the final name at the commit time.
I am hoping it would be the former.
> * Additionally we need to obtain the .lock for the loose refs
> file to keep guarantees, though we should close the file
> descriptor as we don't wand to run out of file descriptors.
Yes, this last point is important.
next prev parent reply other threads:[~2015-01-15 23:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-15 22:36 [RFC] Introducing different handling for small/large transactions Stefan Beller
2015-01-15 22:46 ` Jeff King
2015-01-15 23:24 ` Stefan Beller
2015-01-15 23:53 ` Jeff King
2015-01-16 19:23 ` Stefan Beller
2015-01-15 23:34 ` Junio C Hamano [this message]
2015-01-16 19:00 ` Stefan Beller
2015-01-18 12:13 ` Michael Haggerty
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