Am 26.01.2016 um 22:50 schrieb Stefan Beller:
On Tue, Jan 26, 2016 at 12:59 PM, Jens Lehmann <Jens.Lehmann@xxxxxx> wrote:
Ok. Though we might wanna call it submodule.autoUpdate, as initializing
it is only the prerequisite for automatically updating submodules. And
I believe automatically updating is the thing we're after here, right?
I am not sure here, too. I would not mind an occasional "git submodule
update"
for whenever I want upstream to come down on my disk.
However that's what I
do with "git pull" in the non-submodule case, so you'd expect git pull to
also run the update strategies for all submodules which are configured to
autoUpdate?
That makes sense to me. Though I never use "git pull" to begin with.
I always use fetch and see how to go from there (merge or rebase
after inspecting the code I fetched). That would mean we want to
add the autoUpdate strategy to merge/rebase and the fetching of
submodules to the fetch command?
Hmm, maybe autoUpdate promises too much.
Yes, this very much. I feel like I get burned whenever I send a large
patch series.
So I want to have this first feature be the smallest "operational
unit" that makes sense.
Agreed.
After all this config is
just about which submodules are chosen to be updated on clone and
submodule update, not on all the other work tree manipulating
commands.
So you'd imagine that "git submodule update" would remove the
submodule and setup an empty directory in case that submodule is
not configured ? (after switching branches or when just having cloned
that thing.)
Not as a result of the label feature we are talking about here,
I think that should just do what currently happens to removed
submodules: they are left populated but are ignored by status,
diff and submodule update. Removing the content is part of the
recursive submodule update topic.
And it's similar to what sparse does. So what about calling that
"submodule.updateSparse"? Or maybe "submodule.sparseCheckout"?
Suggestions welcome.
I'd only suggest when it's clear to me what that option actually does. :)
Fair enough! ;-)
And the
fetch command needs to fetch submodule changes too when they happen in
a branch where this submodule is part of a label group configured to be
updated automatically, no matter what is currently found in the work
tree.
Right, as said above fetch needs to fetch all the submodules as well. I
wonder
if it needs to fetch all submodule sha1s only or just try to get as
much from the
submodule as possible.
Right now we just do a simple fetch, but only fetching the SHA-1s could
be an optimization useful for busy submodules later on.
I'd rather not call it optimisation, but a correctness thing. What if you
force-pushed other content to the submodule (the sha1 is gone and
maybe should not be reachable)or the other case where you want to
clone the submodule with depth 1 (that is a serious case, which currently
breaks). In the shallow submodule case you need to have the exact sha1
for cloning, otherwise it doesn't work correctly.
I'm convinced. Correctness it is! :-)
So I'd propose to:
*) Initialize every submodule present on clone or newly fetched when
the autoUpdate config is set.
What if you clone branch A and then switch to B ? B has a submodule which
was not initialized in A. I do not think initializing on clone/fetch
is the right thing
to do, but rather the branch switching command (checkout) shall make sure
all its autoUpdate/autoInitialze submodules are setup properly, no?
I disagree. If you init all submodules on clone/fetch you might need
to change the upstream URL right after that. You can't do that on a
subsequent branch switch which needs to initialize the submodule again,
as the former deinit did nuke that configuration.
So we need to keep the information around, which we do by keeping
all the modules initialized all the time.
Yup.
*) Automatically fetch only those submodules that are changed in
a commit where they have a label configured (in the commit's
.gitmodules or locally) that is to be checked out.
Not sure I follow here.
We could restrict fetch to not fetch everything but just those changes
needed for sparse submodule update. To be able to do that it would
have to examine the fetched superproject commits if a submodule changed
and if it is configured to be automatically updated in that commit.
ok, that's an optimisation for later? (not strictly needed for the first series)
Definitely.
*) Let "git submodule update" update only those submodules that
have an autoupdate label configured.
Why not update all initialized submodules? (In my imagination
"all initialized submodules" are equal to "all submodules the user is
interested in", i.e. when going from branch A to B, the checkout will
(de-)init submodules as necessary.
And throw away any customization the user did (to the URL or other
configurations)?
Without this sparse/label/group functionality, init is the way the
user tells us he is interested in a submodule. But when configuring
a label/name/path to update, the old meaning of init is obsolete
and superseded by the new mechanism.
Or if we keep it at "--initSubmodule" only, which only initializes
a subset of new submodules, the meaning is not superseded.
By having the initSubmodule thing set, the user tells us "I am interested
in all currently initialized submodules plus some more in the future, but
these have not arrived yet. To know which submodules I mean in the future
apply this pattern."
Let's take the simplest case:
A user is interested in all the submodules. So currently they clone
and initialize all of them. When upstream adds a new submodule, their
expectation is broken that all submodules are there and checked out.
by having the autoInit option, we'd just initialize any new submodule
and the user assumption "I have all the submodules" is true after
any "submodule update".
By that point of view, we would not need to keep all submodules initialized,
but only those the user is interested in. No need to have complicated
branch switching rules, but just as now "plus some futureproof rules
to declare my interest of submodules".
I'm not sure what "complicated branch switching rules" you are
referring to here, as far as I can see these only happen when we do
not automatically initialize all submodules. What am I missing?
You'd have to deal with initialized but not to be updated submodules
anyway (due to the user choosing a different label or upstream
changing label assigments). So it looks to me like the approach to
initialize them all as soon as they appear is easier to grok. And
update, diff and status will just skip all submodules that don't
match the configured label(s).
Additionally this will make it easier to e.g. change the upstream
URL of the submodules in one go, as this has to be done after they
have been initialized. If you clone the android repo from a local
mirror it'd be great to just update all URL settings once right
after clone instead of having to do that again each time you choose
a different group.
So I'm not per se against a lazy submodule init like you seem to
propose it, but I believe it'd be better to just init them all as
soon as they appear.
# The prefix * denotes a label as found in .gitmodules
# : goes before names
# path are prefixed ./ currently
# both path and names need work
Question: how do I configure all submodules to be automatically
initialized without having to give them a label? "./*"? Or just
setting the option without a specific value?
I'd guess ./* should do. Path wildcard patterns are not supported in this
series, but I think it would be a viable way.
Ok.
# no --init necessary, partially initializes submodules (only
those
which
# were specified by label, name or path)
$ git submodule update
Yup. Just like they will be fetched if they haven't been yet they
should be initialized if they haven't been yet but are configured
to be automatically updated.
# time passes, upstream may have added new submodules and we get
them
without
# extra commands!
$ git submodule update
# The above configuration can be given to git clone directly via:
$ git clone --init-submodule=*labelA ...
Ok. Expecially nice is the ability to also give names and paths to
"--init-submodule". (but maybe that option should be called
"--autoupdate-submodule" for the reasons stated above?)
If I can understand the discussion above a bit further, I'd be happy
to rename the option.
I think we have some different opinions on when
submodules are initialized (the invariant of what an initalized submodules
means), and resulting from that we also have different opinions on when
to do the (de-)init.
Yes. But I hope my arguments will convince you ;-)
--autoupdate-submodule seems to be one step ahead of my current understanding?
Yes, sorry for the confusion.
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