When you run `jj co abc123` and that commit is already checked out, we
just print a message. The condition for that assumed that the checkout
existed, which it won't if you just ran `jj workspace forget`. Let's
avoid that crash, especially since `jj co` is an easy way to restore
the working copy if you had accidentally run `jj workspace forget`
(though `jj undo` is even easier).
It seems helpful to show in the log output which commit is checked out
in which workspace, so let's try that. I made it only show the
information if there are multiple checkouts for now.
In workspaces added after the initial one, the idea is to have
`.jj/repo` be a file whose contents is a path to the location of the
repo directory in some other workspace.
As part of creating a new repository, we create an open commit on top
of the root and set that as the current checkout. Now that we have
support for multiple checkouts in the model, we also have support for
zero checkouts, which means we don't need to create that commit on top
of the root when creating the repo. We can therefore move out of
`ReadonlyRepo`'s initialization code and let `Workspace` instead take
care of it. A user-visible effect of this change is that we now create
one operation for initilizing the repo and another one for checking
out the root commit. That seems fine, and will be consistent with the
additional operation we will create when adding further workspaces.
Because we record each workspace's checkout in the repo view, we can
-- unlike other VCSs -- let the user refer to any workspace's checkout
in revsets. This patch adds syntax for that, so you can show the
contents of the checkout in workspace "foo" with `jj show foo@`. That
won't automatically commit that workspace's working copy, however.
If the workspace is shared with a Git repo, we sometimes update Git's
HEAD ref. We should get the new checkout from the right workspace ID
when doing that (though I'm not sure we'll ever support sharing the
working copy with Git in a non-default workspace).
When importing Git HEAD, we already use the right workspace ID for the
new checkout, but the old checkout we abandon is always the default
workspace's. We should fix that even if we will never support sharing
a working copy with Git in a non-default workspace.
Before committing the working copy, we check if the working copy is
checked out to the commit we expect based on the repo's view. We
always use the default workspace's checkout, so we need to fix that.
We detect concurrent working copy changes by checking that the old
commit matches the repo's view. We should use the current workspace
when looking up the checkout in the view.
When checking out a new commit, we look at the old checkout to see if
it's empty so we should abandon it. We current use the default
workspace's checkout. We need to respect the workspace ID we're given
in `MutableRepo::check_out()`, and we need to be able to deal with
that workspace not existing yet (i.e. this being the first checkout in
that workspace).
This patch teaches the `View` object to keep track of the checkout in
each workspace. It serializes that information into the `OpStore`. For
compatibility with existing repos, the existing field for a single
workspace's checkout is interpreted as being for the workspace called
"default".
This is just an early step towards support for multiple
workspaces. Remaining things to do:
* Record the workspace ID somewhere in `.jj/` (maybe in
`.jj/working_copy/`)
* Update existing code to use the workspace ID instead of assuming
it's always "default" as we do after this patch
* Add a way of indicating in `.jj/` that the repo lives elsewhere and
make it possible to load a repo from such workspaces
* Add a command for creating additional workspaces
* Show each workspace's checkout in log output
The `.jj/` directory contains information about two distinct parts:
the repo and the working copy. Most subdirectories are related to the
repo; only `.jj/working_copy/` is about the working copy. Let's move
the repo-related bits into a new `.jj/repo/` subdirectory. That makes
it clearer that they're related to the repo. It will probably also be
easier to manage when we have support for multiple workspaces backed
by a single repo.
This adds a `jj move [--from <rev>] [--to <rev>] [-i]` command, which
lets you move some changes from one commit into another. `jj
squash/amend` is just a special case of this new command. Except for
that command's more specialized help text, instructions, etc., it
could be implemented as simply `jj move --to @-`.
I thought it was a bit unclear which part of the process was
interactive (it's only choosing parts of the diffs that is
interactive, not choosing destination or anything else).
The `DescendantRebaser` was designed to help with rebasing in two
different use cases: 1) after regular rewriting of commits where the
change ID is preserved, and 2) after importing moved branches from
other repo (e.g. backing Git repo or remote). Many of the tests are
for the second use case, such as where a branch was moved
forward. However, I just noticed that there's a pretty common scenario
from the first use case that is not supported.
Let's say you have this history:
```
D
|
C C'
|/
B B'
|/
A
```
Here we want C' to be rebased onto B' and then D to be rebased onto
C''. However, because of the support for moving branches forward, we
would not rebase commits that were already rewritten, such as C' here
(see affected tests for details), which resulted in D getting rebased
onto C', and both B and B' remaining visible.
I think I was thinking when I designed it that it would be nice if you
could just tell `DescendantRebaser` that any descendants of a commit
should be moved forward. That may be useful, but I don't think we'll
want that for the general case of a branch moving forward. Perhaps
we'll want to make it configurable which branches it should happen
for. Either way, the way it was coded by not rebasing already
rewritten commits did not work for the case above. We may be able to
handle both cases better by considering each rewrite separately
instead of all destinations at once. For now, however, I've decided to
keep it simple, so I'm fixing the case above by sacrificing some of
the potentially useful functionality for moving branches forward.
Another fix necessary for the scenario shown above was to make sure we
always rebase C' before D. Before this patch, that depended on the
order in the index. This patch fixes that by modifying the topological
order to take rewrites into account, making D depend not only on C but
also on C'. (I suppose you could instead say that C depends on both B
and C'; I don't know if that'd make a difference.)
Despite what the documentation said, we don't clear the record of
rewritten and abandoned commits at the end. This change fixes that,
and adds a test showing that it's possible to call
`MutableRepo::rebase_descendants()` multiple times.
We allow rebasing to a descendant, but that causes divergence because
the old commit remains visible. You could imagine making it work so
`jj rebase -r B -d D` on a linear chain "A-B-C-D" reorders it to
"A-C-D-B", but we don't do that yet, so let's just prevent the
divergence for now.
Now that we have the operation ID recorded in the working copy state,
we can tell if the working copy is stale. When it is, we update it to
the repo view's checkout.
When there are concurrent operations that want to update the working
copy, it's useful to know which operation was the last to successfully
update the working copy. That can help use decide how to resolve a
mismatch between the repo view's record and the working copy's
record. If we detect such a difference, we can look at the working
copy's operation ID to see if it was updated by an operation before or
after we loaded the repo.
If the working copy's record says that it was updated at operation A
and we have loaded the repo at operation B (after A), we know that the
working copy is stale, so we can automatically update it (or tell the
user to run some command to update it if we think that's more
user-friendly).
Conversely, if we have loaded the repo at operation A and the working
copy's record says that it was updated at operation B, we know that
there was some concurrent operation that updated it. We can then
decide to print a warning telling the user that we skipped updating
because of the conflict. We already have logic for not updating the
working copy if the repo is loaded at an earlier operation, but maybe
we can drop that if we record the operation in the working copy (as
this patch does).
When importing git HEAD in a working copy shared with git, we reset
the working copy to the new commit at the end. If we fail to reset the
working copy, we shouldn't commit the operation. This patch mostly
fixes that by locking the working copy while we commit the
operation. There's still a small risk that the operation commits and
we fail to write the working copy state, but there's not much we can
do about that (or it's not worth the effort anyway).
