Re: [BUG] Segfault with rev-list --bisect

On Wed, Mar 4, 2015 at 6:44 PM, Junio C Hamano [off-list ref] wrote:

Troy Moure [off-list ref] writes:

quoted

git rev-list --bisect --first-parent --parents HEAD --not HEAD~1

Hmm, as "rev-list --bisect" is not end-user facing command (it is
purely an implementation detail for "git bisect") and we never call
it with --first-parent, I am not sure if it is worth labelling it as
a BUG.  Surely, the command can refuse to operate when it sees both
options given, but that would be a fairly low priority.

Hrm, ok. I didn't realize "--bisect" is only intended to be used by git-bisect
(although I suppose the fact that it treats ref/bisect/* specially should have
been a hint). If uses of "--bisect" other than by git-bisect are considered
unsupported, IMO it would be good to say that in the documentation - right now
it looks like just another rev-list parameter. (I realize rev-list itself is
"plumbing", but that's not the same as "not user facing", is it?)

If you're curious, I ran into this because I am working on a script that can be
run repeatedly to process commits, and uses git notes to mark commits that have
been processed.  Parents are always processed before their children, so if a
commit has a note, it means all its ancestors also have notes. I want to
quickly find the set of commits that have not yet been processed. I am thinking
of finding the "boundary" commits (commits that have a note and at least one
child that does not) by using a binary search to find the boundary commit on
the first-parent chain, and then recursively doing the same thing starting from
each non-first parent of each merge commit between the boundary commit and the
starting point.

Upon further thought, it's probably better to just read the whole first-parent
chain and do the binary search in the script, since "git rev-list --bisect"
would have generate the chain each time it's called. But I'd already run into
the segfault, so I thought I'd report it.

Of course, I'd appreciate any thoughts or comments on the problem I'm trying to
solve as well.

Thanks,
Troy