Re: git-notes, how do they work?

From: Ulrich Spoerlein <uspoerlein@gmail.com>
Date: May 12, 2012, 11:27 UTC
Message-ID: <20120512112707.GP71676@acme.spoerlein.net>
In-Reply-To: <CACsJy8DRujbCc5Etod8eCoUW5+SxK-1qbJaAYw7gdvkO2SdSRw@mail.gmail.com>

On Sat, 2012-05-12 at 18:01:40 +0700, Nguyen Thai Ngoc Duy wrote:

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> On Sat, May 12, 2012 at 5:43 PM, Ulrich Spoerlein <uspoerlein@gmail.com> wrote:
> > IIUC refs/notes/commits points to the latest note, which points to HEAD.
> > However, there's no reference that points to the note pointing to
> > HEAD^1, so how will it not be garbage collected?
> 
> No. refs/notes/commits points to a commit, whose tree contains all
> notes at the last time a note is changed. This commit has a parent
> commit that stores note snapshot of the previous change and so on..
> 
> refs/notes/commits is an ordinary ref, which is searched for
> reachability at gc time, so all notes (even replaced notes) cannot be
> deleted.

Cool, I believe this is then a bug with how svn2git works when it's being restarted to do incremental conversions and have contacted the author of that code.

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> > How can it be pushed to a remote repository?
> 
> What I wrote about were my findings while I studied the notes code.
> I'm new to it too. And I believe there's no mechanism to transfer
> notes. Of course you can transfer resfs/notes/commits like any other
> refs, but the objects those notes are attached to might or might not
> exist at destination repo.

Pushing them to github works fine like this:

[remote "github"]
        url = github.com:freebsd/freebsd.git
        push = +refs/heads/master:refs/heads/master
        push = +refs/heads/release/*:refs/heads/release/*
        push = +refs/heads/releng/*:refs/heads/releng/*
        push = +refs/heads/stable/*:refs/heads/stable/*
        push = +refs/notes/*:refs/notes/*

And you will see them displayed in their web UI (at the bottom):

https://github.com/freebsd/freebsd/commit/4bef84bb40695b68a4ccdcec5f847b5a7a302864

But older commits are missing this, most likely because the notes were clobbered before I pushed them, e.g.

https://github.com/freebsd/freebsd/commit/1e7688b79181301805cd4616daa42ae827d74e99#README

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> > I understand that notes cannot point to older notes, as that would make
> > removing/adding notes from/to older commits quite a hassle.
> >
> > So, what am I doing wrong here? How can I avoid notes from disappearing
> > so that each and every one of it remains in the repo?
> -- 
> Duy