Re: [PATCH 0/8] Sequencer Foundations

From: Christian Couder <christian.couder@gmail.com>
Date: May 12, 2011, 08:19 UTC
Message-ID: <BANLkTi=zXWojMOfe9sECUu-X9euCjr4i3w@mail.gmail.com>
In-Reply-To: <20110511131356.GI2676@elie>

Hi,

On Wed, May 11, 2011 at 3:14 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:

Show 11 quoted lines

> Ramkumar Ramachandra wrote:
>
>> Ramkumar Ramachandra (8):
>>   revert: Improve error handling by cascading errors upwards
>>   revert: Make "commit" and "me" local variables
>>   revert: Introduce a struct to parse command-line options into
>>   revert: Separate cmdline argument handling from the functional code
>>   revert: Catch incompatible command-line options early
>>   revert: Introduce head, todo, done files to persist state
>>   revert: Implement parsing --continue, --abort and --skip
>>   revert: Implement --abort processing

I had no time to look at this yet but I will try do to so in the coming days.

Show 23 quoted lines

> The heart is patch 6/8.  I have not thought about this deeply yet, but
> I wonder if it would be simpler if the behavior of "git cherry-pick
> 1..10" looked like this:
>
> . if there is state in .git/sequencer already, error out
> . lock .git/sequencer/head with the lockfile API to prevent
>  concurrent access
> . write current state, including remaining commits to cherry-pick
> . unlock .git/sequencer/head
> . cherry-pick commit #1
> . lock sequencer, check state, update state, unlock
> . cherry-pick commit #2
>  ...
>
> This way, even if cherry-picking causes git to segfault, the sequencer
> state is in good order and we know where to pick up.  More
> importantly, massive refactoring of the merge_recursive API would not
> be needed to keep everything in working order.  An atexit and sigchain
> handler could be added to print advice for the reader about how to
> resume, but that's just an extra hint and it's okay if it sometimes
> doesn't happen sometimes.
>
> What do you think?

I think that the risk at this point might be to overengineer things and to lose time, and then we will perhaps find out that we need to do some refactoring of the merge_recursive API anyway. If we have cherry-pick with --abort, --continue and --skip that just works as well or nearly as well (because it's new) as other stuff it will be already a very good thing. And with enough tests we will hopefully be able to build and refactor safely after that. Maybe we will eventually find out that what you suggest is in fact needed even for cherry-pick with --abort, --continue and --skip, but for now I would prefer trying to make it work with as few changes and work as possible.

Thanks, Christian.