1325327 - mozilla-unified should have a @ bookmark

Status: NEW

(Developer Services :: Mercurial: hg.mozilla.org, defect)

Description

[Mike Hommey [:glandium]]

Per https://www.mercurial-scm.org/wiki/Bookmarks:

    "If you have a bookmark named @ when cloning a remote repository, "hg clone" will check it out by default."

We should have such a bookmark, pointing to central or inbound.

Comment 1

[Gregory Szorc [:gps]]

I'm kind of "meh" about this.

It does provide a UX win for vanilla Mercurial when users `hg clone` manually. But we now offer to clone via the one-line bootstrap and that handles updating to "central" automatically.

We also strongly recommend people use the "firefoxtree" extension when working with mozilla-unified because it converts the bookmarks to read-only labels of the same name. This prevents people from accidentally advancing the bookmarks and causing divergence.

The reason the bookmarks exist at all is to make the repo usable with vanilla Mercurial (otherwise there would be multiple heads on the same named branch). So given that, I suppose it wouldn't be too bad to create the @ bookmark and have "firefoxtree" ignore it. Then again, this is just for a workflow optimization for a one-time thing that people may not run into if they are using the one-line bootstrap. It feels like avoidable complexity for marginal gain.

Comment 2

[Mike Hommey [:glandium]]

Not everybody uses mach bootstrap, and not everybody uses mercurial. For one, if I can turn the git-cinnabar workflow into "git clone hg::https://hg.mozilla.org/mozilla-unified and you're done", that would definitely be a win. And I'm experimenting with defaulting to only expose bookmarks when there are bookmarks. And the most reliable thing I can do then is hoping one of the bookmarks corresponds to the tip of the default branch, but in mozilla-unified's case, it means, depending on the time of day, you can end up with aurora, beta, central or inbound as the HEAD.

Comment 3

[Gregory Szorc [:gps]]

Cleaning out my backlog...

Comment 4

[Gregory Szorc [:gps]]

Attachment: ansible/hg-ssh: store a @ bookmark for mozilla-central (bug 1325327);

Mercurial has a convention that @ is the default bookmark. This
convention isn't used at Mozilla for reasons that are likely
historical.

The presence of the @ bookmark will cause `hg clone` with a vanilla
Mercurial configuration to check out the @ bookmark. @ is also used
as the default for other commands. This is desirable.

In this commit, we set the @ bookmark on the mozilla-unified repo
to be identical to the existing "central" bookmark.

We also teach the firefoxtree extension to treat the @ bookmark
specially when operating on a unified repo. The @ bookmark is
treated as a firefoxtree name so it is exposed in the
server-advertised list. It is also filtered away on the client
when encountered. This makes behavior consistent with other
bookmarks on the mozilla-unified repo.

Users with the previous firefoxtree extension will start seeing
an @ bookmark locally. When they upgrade to the latest
v-c-t and firefoxtree, the @ bookmark will be deleted on next
pull. Non-firefoxtree users will see both the @ and central
bookmarks.

Review commit: https://reviewboard.mozilla.org/r/140832/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/140832/

Comment 5

[Mike Hommey [:glandium]]

Comment on attachment 8869272 [details]
ansible/hg-ssh: store a @ bookmark for mozilla-central (bug 1325327);

https://reviewboard.mozilla.org/r/140832/#review144530

::: hgext/firefoxtree/__init__.py:372
(Diff revision 1)
>                  if bmstore.active == tag:
>                      repo.ui.status('(deactivating bookmark %s)\n' % tag)
>                      bookmarks.deactivate(repo)
>  
> +            # The @ tag is redundant with central. Don't replicate it locally.
> +            if tag == '@':

Per the first hunk in this file, firefoxtrees is not reporting the '@' tag on the server side, why care on the client end?

::: hgext/firefoxtree/__init__.py:422
(Diff revision 1)
> +            # @ and central are the same. So ignore @.
> +            if k != '@' and not resolve_trees_to_uris([k])[0][1]}

Mmmmm actually, shouldn't the @ bookmark still be pulled?

Comment 6

[Gregory Szorc [:gps]]

Comment on attachment 8869272 [details]
ansible/hg-ssh: store a @ bookmark for mozilla-central (bug 1325327);

https://reviewboard.mozilla.org/r/140832/#review144530

> Mmmmm actually, shouldn't the @ bookmark still be pulled?

@ will be pulled by vanilla clients, which is desirable.

The issue is for clients with firefoxtree. The whole point of converting the bookmarks on the server to not-bookmarks is so users don't activate them and move them locally. (Because vanilla Mercurial doesn't have remote refs.) So it seems kinda weird to have tracking labels/not-bookmarks for everything except @. But it is also sub-optimal to not have @. There's no obvious right solution here.

Comment 7

[Julien Cristau [:jcristau]]

Connor can we reconsider this? It's confusing for someone cloning unified to end up with a random branch checked out, e.g. if they end up on a busted autoland revision.

Comment 8

[Connor Sheehan [:sheehan]]

I agree this would be useful to have.

We should ignore adding @ as a firefoxtree special tag, and either keep it as a regular bookmark for firefoxtree clients or just ignore it altogether. Then we can have @ point to central or autoland via the unification daemon config file.

Comment 9

[Mike Hommey [:glandium]]

(In reply to Julien Cristau [:jcristau] from comment #7)

Connor can we reconsider this? It's confusing for someone cloning unified to end up with a random branch checked out, e.g. if they end up on a busted autoland revision.

Or a commit on some other branch, like beta, release or esr.

This still, to this day, tricks people.