It's been a lot of work, but now we're finally able to remove the
`Evolution` state! `jj obslog` still works as before (it just walks
the predecessor pointers).
The removal of hidden heads was just there to help with the transition
away from evolution (#32). Now that we no longer depend on evolution
for removing old heads, we can remove the hack.
This patch teaches `DescendantRebaser` to also update heads. That's
done at the end of the rebase (when `rebase_next()` starts returning
`None`), which is a little weird. We should probably change the
interface, but this will do for now.
With this change, we should no longer need to remove hidden heads when
the transaction commits. That will remove one of the last bits of
dependence on evolution from most commands (#32).
Now that we remove hidden heads whenever a transaction commits,
`non_obsolete_heads()` should always be the same as `all_heads()`,
except during a transaction. I don't think we depend on the difference
even during a transaction. Let's simplify a bit by removing the revset
function `all_heads()` and renaming `non_obsolete_heads()` to
`heads()`. This is part of issue #32.
This is similar to how a recent change taught `DescendantRebaser` to
update branches pointing to rewritten commits. Now we also update the
checkout if it pointed to a rewritten commit.
This patch moves the logic for updating branches from
`update_branches_after_rewrite()` into `DescendantRebaser`. The
branches are now updated along with each rebased commit rather than
all being updated at the end. The new code uses the information about
rewritten and abandoned commits that `DescendantRebaser` gets from
`MutableRepo`. That is different from the old code, which used the
evolution state. This patch thus moves us one step closer to removing
evolution (#32).
I'm going to teach `DescendantRebaser` to also update local branches
pointing to rewritten commits, taking over the responsibility from
`rewrite::update_branches_after_rewrite()`. For commits that have been
rewritten as multiple new commits (divergent, not split), that
function makes local branches pointing to the old commit point to all
the new commits. To replicate that behavior in `DescendantRebaser`, it
needs to know about divergent changes. This change addresses that.
I recently made the CLI remove hidden heads when a transaction is
committed (38474a9). Let's move that to `Transaction::commit()`, so
the library crate becomes more similar to how the CLI behaves and more
similar to our evolution-less future (#32).
The next patch would otherwise make this test fail because
"transaction 2" tries to point a branch to a commit that's not visible
(because it's created by the concurrent "transaction 1").
This is part of removing support for evolution (#32). Since
`CommitBuilder` now records rewritten commits in `MutableRepo`, we can
use that recorded information to automatically rebase descendants.
When we remove support for evolution (#32), we need to still make it
easy for application code to rebase descendants of rewritten and
abandoned commits. The way applications currently do that is by using
e.g. `CommitBuilder::for_rewrite_from()` followed by
`evolve_orphans()`. This patch puts some bookkeeping in `MutableRepo`
for rewritten and abandoned commits, along with a function for
creating a `DescendantRebaser` based on it. I'll then make
`CommitBuilder` record rewritten commits there.
The default branch relies on checking the value of `HEAD`. The `empty_git_commit` function updates the ref `refs/heads/main`, but since `HEAD` was never updated to point to that ref, the default branch can't be determined. The fix is to explicitly set `HEAD`.
Personally, this test failed reliably for me on macOS. I don't know why this behavior would be non-deterministic on other platforms.
It seems it wasn't Windows that behaved differently when it comes
getting the remote's default branch; the test failed on Ubuntu
too.
The documentation for `Remote::default_branch()` says that it can be
called even after the connection has been closed, but let's see if
calling it while the connection is open helps anyway. To do that, we
have to replicate what `Remote::fetch()` does.
Descendants of abandoned commits should be rebased onto their parents,
or the rewritten parents if they had been rewritten. This patch
teaches `DescendantRebaser` to do that. It updates `jj rebase -r` to
use the functionality. I plan to also use it in `jj abandon`
(naturally, given the name), and for rebasing descendants of deleted
refs imported from `jj git refresh/fetch/push`.
The fact that `DescendantRebaser` visits some commits that don't need
to be rebased is mostly an implementation detail. I can't think of a
reason that callers would care about these commits.
The command's help text says "Abandon a revision", which I think is a
good indication that the command's name should be `abandon`. This
patch renames the command and other user-facing occurrences of the
word. The remaining occurrences should be removed when I remove
support for evolution.
This patch moves the function for updating branches after rewrite from
`commands.rs` into `rewrite.rs`.
It also changes the function to update branches even if they were
conflicted or become conflicted. I think that seems better than
leaving branches on old commits. For example, let's say you have start
with this:
```
C main
|
B origin@main
|
A
```
You now pull from origin, which has updated the main branch from B to
B'. We apply that change to both the remote branch and the local
branch, which results in a conflict in the local branch:
```
C main?
|
B B' main? origin@main
|/
A
```
If you now rewrite C to C', the conflicted main branch will still
point to C, which is just weird. This patch changes that so the
conflicted side of main gets repointed to C'.
I also refactored the code to reuse our existing
`MutableRepo::merge_single_ref()`, which improves the behavior in
several cases, such as the conflict-resolution case in the last test
case.
As the updates test case shows, when rebasing forward, we missed
commits that fork off from the section between the source and the
destination.
As part of the fix, I also restructured the code a bit to prepare for
support for rebasing descendants of multiple rewritten commits.
Before this change, you could end up with an index segment with 10
commits, then a child segment with 9 commits, then another child with
8 commits, and so on. That's not what I had intended. This changes
makes it so we squash if a segment has more than half as many commits
as its parent instead.
Git doesn't want `.git` entries in its trees, so at least when using
the Git backend, we need to ignore such paths. Let's just ignore
`.git` paths regardless of backend to keep it simple.
Closes#24.
When I added the function for rebasing descendants, I forgot to call
the existing `rebase()` function and instead simply created a new
commit with the new parents but the old contents.
This should be useful in lots of places. For example, `jj rebase -r`
currently rebases all descendants, because that's what the auto-evolve
feature does. I think it would be nice to instead copy from
Mercurial's `-s` flag for also rebasing descendants. Then `jj rebase
-r` can be made to pull a commit out of a stack, rebasing descendants
onto the rebased commit's parents. I also intend to use this
functionality for rebasing descendants when remote branches have been
rewritten.
The auto-rebasing of descendants doesn't work if you have an open
commit checked out, which means that you may still end up with orphans
in that case (though that's usually a short-lived problem since they
get rebased when you close the commit). I'm also about to make
branches update to successors, but that also doesn't work when the
branch is on a working copy commit that gets rewritten. To fix this
problem, I've decided to let the caller of `WorkingCopy::commit()`
responsible for the transaction.
I expect that some of the code that this change moves from the lib
crate to the cli crate will later move back into the lib crate in some
form.
With this change, we no longer fail if the user moves a branch
sideways or backwards and then push.
The push should ideally only succeed if the remote branch is where we
thought it was (like `git push --force-with-lease`), but that requires
rust-lang/git2-rs#733 to be fixed first.
Now that we have our own representation of branches and tags, let's
update them when we import git refs. The View object's git refs are
now just a record of what the refs are in the underlying git ref last
time we imported them (we don't -- and won't -- provide a way for the
user to update our record of the git refs). We can therefore do a nice
3-way ref-merge using the `refs` module we added recently. That means
that we'll detect conflicts caused by changes made concurrently in the
underlying git repo and in jj's view.
I've finally decided to copy Git's branching model (issue #21), except
that I'm letting the name identify the branch across
remotes. Actually, now that I think about, that makes them more like
Mercurial's "bookmarks". Each branch will record the commit it points
to locally, as well as the commits it points to on each remote (as far
as the repo knows, of course). Those records are effectively the same
thing as Git's "remote-tracking branches"; the difference is that we
consider them the same branch. Consequently, when you pull a new
branch from a remote, we'll create that branch locally.
For example, if you pull branch "main" from a remote called "origin",
that will result in a local branch called "main", and also a record of
the position on the remote, which we'll show as "main@origin" in the
CLI (not part of this commit). If you then update the branch locally
and also pull a new target for it from "origin", the local "main"
branch will be divergent. I plan to make it so that pushing "main"
will update the remote's "main" iff it was currently at "main@origin"
(i.e. like using Git's `git push --force-with-lease`).
This commit adds a place to store information about branches in the
view model. The existing git_refs field will be used as input for the
branch information. For example, we can use it to tell if
"refs/heads/main" has changed and how it has changed. We will then use
that ref diff to update our own record of the "main" branch. That will
come later. In order to let git_refs take a back seat, I've also added
tags (like Git's lightweight tags) to the model in this commit.
I haven't ruled out *also* having some more persistent type of
branches (like Mercurials branches or topics).
I'm about to add some support for branches and tags (for issue #21)
and it seems that we didn't have explicit testing of merging of
views. There was `test_import_refs_merge()` in `test_git.rs` but
that's specifically for git refs. It seems that it's made obsolete by
the tests added by this commit, so I'm removing it.
I had previously created commit messages based only on the ref name,
which meant that `commit4` and `commit5` ended up being the same
commit. This fixes that problem.
There were some tests that discarded a transaction only because it
used to be easier to do that than to commit and reload the repo. We
get the new repo back when we commit the transaction these days, so
now it's often easier to commit the transaction instead.
When there are two concurrent operations, we would resolve conflicting
updates of git refs quite arbitrarily before this change. This change
introduces a new `refs` module with a function for doing a 3-way merge
of ref targets. For example, if both sides moved a ref forward but by
different amounts, we pick the descendant-most target. If we can't
resolve it, we leave it as a conflict. That's fine to do for git refs
because they can be resolved by simply running `jj git refresh` to
import refs again (the underlying git repo is the source of truth).
As with the previous change, I'm doing this now because mostly because
it is a good stepping stone towards branch support (issue #21). We'll
soon use the same 3-way merging for updating the local branch
definition (once we add that) when a branch changes in the git repo or
on a remote.
