I made import_refs() not preserve commits referenced by remote branches at
520f692a4600 "git: on import_refs(), don't preserve old branches referenced by
remote refs." The idea is that remote branches are weak, and commits referenced
by these refs can be freely rewritten by future local changes without moving
the refs. I don't think that's wrong, but 520f692a4600 also made "new" remote
changes be abandoned by old remote refs. This problem occurs only when
git.auto-local-branch is off.
I think there are two ways to fix the problem:
a. pin non-tracking remote branches just like local refs
b. pin newly fetched refs in addition to local refs
This patch implements (b) because it's simpler and more obvious that the
fetched commits would never be abandoned immediately.
This add support for custom `jj` binaries to use custom working-copy
backends. It works in the same way as with the other backends, i.e. we
write a `.jj/working_copy/type` file when the working copy is
initialized, and then we let that file control which implementation to
use (see previous commit).
I included an example of a (useless) working-copy implementation. I
hope we can figure out a way to test the examples some day.
This makes `Workspace::load()` look a new `.jj/working_copy/type` file
in order to load the right working copy implementation, just like
`Repo::load()` picks the right backends based on `.jj/store/type`,
`.jj/op_store/type`, etc. We don't write the file yet, and we don't
have a way of adding alternative working copy implementations, so it
will always be `LocalWorkingCopy` for now.
Our internal working copy implementations at Google will need the
commit so they can walk history backwards until they get to a "public"
commit. They'll then use that to tell build tools and virtual file
systems to present that as a base.
I'm not sure if we'll need to update `reset()` too. It's currently
only used by `jj untrack`, which doesn't change the commit's parent,
so it wouldn't affect any history walks.
`ReadonlyRepo::init()` takes callbacks for initializing each kind of
backend. We called these things like `op_store_initializer`. I found
that confusing because it is not a `OpStoreFactory` (which is for
loading an existing backend). This patch tries to clarify that by
renaming the arguments and adding types for each kind of callback
function.
This patch adds MutableRepo::track_remote_branch() as we'll probably need to
track the default branch on "jj git clone". untrack_remote_branch() is also
added for consistency.
We could instead migrate the storage types to (local_branches, remote_views),
but that would be more involved and break forward compatibility with little
benefit. Maybe we can do that later when we introduce remote tags.
The state field isn't saved yet. git import/export code paths are migrated,
but new tracking state is always calculated based on git.auto-local-branch
setting. So the tracking state is effectively a global flag.
As we don't know whether the existing remote branches have been merged in to
local branches, we assume that remote branches are "tracking" so long as the
local counterparts exist. This means existing locally-deleted branch won't
be pushed without re-tracking it. I think it's rare to leave locally-deleted
branches for long. For "git.auto-local-branch = false" setup, users might have
to untrack branches if they've manually "merged" remote branches and want to
continue that workflow. I considered using git.auto-local-branch setting in the
migration path, but I don't think that would give a better result. The setting
may be toggled after the branches got merged, and I'm planning to change it
default off for better Git interop.
Implementation-wise, the state enum can be a simple bool. It's enum just
because I originally considered to pack "forgotten" concept into it. I have
no idea which will be better for future extension.
It's going to be easier to define a `LockedWorkingCopy` trait if it
doesn't need to borrow from `WorkingCopy`, so let's remove the
reference we currently have and have
`LockedLocalWorkingCopy::finish()` return the new `LocalWorkingCopy`
instead.
I think the main disadvantage is that we now have to remember to
replace the old `LocalWorkingCopy` instance by the new one, whereas
the compiler would remind us before this commit. We could make
`start_modification()` take an owned `self`, but that would be a bit
annoying to work with when we have the instance stored in a field.
I'm about to make `LockedLocalWorkingCopy` not borrow from
`LocalWorkingCopy`. That will make it easier to forget to update any
`LocalWorkingCopy` variables when the modifications have been
committed. This patch introduces a wrapper around
`LockedLocalWorkingCopy` to help prevent that.
Thanks to Yuya for the suggestion.
`LocalWorkingCopy::check_out()` can be expressed using the planned
`WorkingCopy` trait, so it doesn't need to be in the trait itself
`WorkingCopy`. I wasn't sure if I should make it a free function in
`working_copy`, but I ended up moving it onto `Workspace`.
Since set_remote_branch_target() is called while merging refs, its tracking
state shouldn't be reinitialized. The other callers are migrated to new setter
to keep the story simple.
This isn't important, but I'm going to change remote_targets to store RemoteRef
instead of RefTarget, so I went ahead and change the other field types as well.
We could fix do_git_clone() instead, but it seemed a bit weird that the
git_repo_path is relative to the store path which is unknown to callers.
Fixes#2374
There's a subtle behavior change. Unlike the original remove_remote_branch(),
remote_views entry is not discarded when the branches map becomes empty. The
reasoning here is that the remote view can be added/removed when the remote
is added/removed respectively, though that's not implemented yet. Since the
serialized data cannot represent an empty remote, such view may generate
non-unique content hash.
These functions depend heavily on the underlying data structure, and I haven't
decided abstract View API to access to per-remote data types. Let's use the
underlying data type for now.
I'm planning to add support for untracked remote branches, and under that
model, there will be many remote branches without local counterparts. That's
the main reason why remote branches are grouped by remote, not by branch name.
The added helper functions will be used by simple_op_store and view.
get_branch() would need to reconstruct the remote_targets map if we migrate
the underlying data structure to per-remote views. Let's remove the method as
it is only used in tests.
It seems pretty clear from the context. Turns out we only use the
function in a test case. Maybe we don't even need it. It's easy to
provide it, though.
The `TreeStateError` type is specific to the current local-disk
working-copy backend, so it should not be part of the generic
working-copy interface I'm trying to create.
I think some of the errors variants in `CheckoutError` are too
specific to the local-disk implementation. Let's merge them and make
them less specific, so it's easier to define a reasonable trait for
the working copy.
As I'm going to split branches into per-remote map, .get_branch(name) will need
to gather remote branches by name to construct remote_targets map. Let's instead
iterate local/remote branches separately. I also migrated diffing of the other
kinds of refs to filter out unchanged entries upfront.
