Re: [PATCH 0/5] not making corruption worse

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 17, 2015, 22:54 UTC
Message-ID: <xmqqh9tjme0l.fsf@gitster.dls.corp.google.com>
In-Reply-To: <20150317073730.GA25267@peff.net>

Jeff King <peff@peff.net> writes:

Show 7 quoted lines

> But it strikes me as weird that we consider the _tips_ of history to be
> special for ignoring breakage. If the tip of "bar" is broken, we omit
> it. But if the tip is fine, and there's breakage three commits down in
> the history, then doing a clone is going to fail horribly, as
> pack-objects realizes it can't generate the pack. So in practice, I'm
> not sure how much you're buying with the "don't mention broken refs"
> code.

I think this is a trade-off between strictness and convenience. Is it preferrable that every time you try to clone a repository you get reminded that one of its refs point at a bogus object and you instead have to do "git fetch $there" with a refspec that excludes the broken one, or is it OK to allow clones and fetches silently succeed as if nothing is broken?

If the breakage in the reachability chain is somewhere that affects a branch that is actively in use by the project, with or without hiding a broken tip, you will be hit by object transfer failure and you need to really go in there and fix things anyway. If it is just a no-longer-used experimental branch that lost necessary objects, it may be more convenient if the system automatically ignored it.

In some parts of the system there is a movement to make this trade off tweakable (hint: what happened to the knobs to fsck that allow certain kinds of broken objects in the object store? did the topic go anywhere?). This one so far lacked such a knob to tweak, and I view your paranoia bit as such a knob.