Re: Determining commit reachability

From: Artur Skawina <art.08.09@gmail.com>
Date: Sep 6, 2010, 05:04 UTC
Message-ID: <4C847661.3020800@gmail.com>
In-Reply-To: <20100906031700.GA25012@sigill.intra.peff.net>

On 09/06/10 05:17, Jeff King wrote:

Show 13 quoted lines

> On Sun, Sep 05, 2010 at 10:34:11PM +0200, Artur Skawina wrote:
> 
>> Given commit C, refs (branches) R, S and T what would be the best way
>> to test whether 'C' is reachable from any of the heads?
>>
>> Checking if `git rev-list -n1 O ^R ^S ^T` produces any output is what
>> i came up with; is there a better (ie faster) solution?
> 
> I think that is about as fast as you will get. You could try something
> with git-merge-base, but it should be about the same speed.
> 
> Note that neither will tell you _which_ head the target was reachable
> from. For that, given the current interface you have to test each head

As i think i'll only need this to prevent leaking (private) commits that wouldn't be reachable from the (public) heads, just catching the unreachable ones should be enough.

$ time git rev-list -n1 v2.6.12 ^v33 ^v35 0m2.333s user 0m0.040s system 0m2.379s elapsed 99.77% CPU $ time git rev-list -n1 v2.6.36-rc2 ^v33 ^v35 76be97c1fc945db08aae1f1b746012662d643e97 0m0.500s user 0m0.010s system 0m0.514s elapsed 99.13% CPU

A bit expensive, but I guess should it become a problem I could cache the result and/or blacklist the client.

Thanks,

artur