This is much simpler and I was slightly surprised that it doesn't have
much impact on performance. I tried `jj --ignore-working-copy diff -s
--from root --to v5.15` in the Linux kernel repo, and there was
perhaps a 1.5% slowdown (508 ms -> 515 ms). In more normal cases (like
diffing a single commit against its parent), I couldn't measure any
difference at all.
It's useful to have a more readable `Debug` format for `Vec<u8>`
(`"foo"` is better than `[102, 111, 111]`). It might also make types
in function signatures and elsewhere more readable.
If one side changes the contents and one side changes the executable
bit, we get a non-trivial conflict in the `TreeValue`s, but once we've
split them up into `FileId`s and bools, we can trivially resolve them
separately, without having to read file contents.
It seems generally useful to be able to simplify a conflict, and it's
not specific to merging trees, so let's move it to
`conflicts.rs`. Once we're done with the migration to tree-level
conflicts, I think `Conflict::simplify()` will remain but
`tree::simplify_conflict()` will be gone.
The tests I added there are quite similar to those of
`trivial_merge()`. I hope we can make `Conflict::simplify()` call
`trivial_merge()` later. I think it would also make sense to move
`trivial_merge()` onto `Conflict`, or at least have a
`Conflict::resolve_trivial()` calling `trivial_merge()`.
Since we switched to the new `conflicts::Conflict` type, we represent
a missing tree entry by a `None` value in the conflict, not a missing
"add", so the condition removed in this commit will never happen, and
the case will be handled by the case just below it instead.
I don't know why I made it return an owned value. It seems like an
unnecessary restriction that the value implements `Clone`, so let's
return a reference instead.
This handles the basic case of where the matcher says that a whole
subtree is not matched. In the Linux repo, That's already enough to
speed up `jj --ignore-working-copy files samples` from 298 ms to 129
ms.
When using a sparse working copy (e.g. with no files at all) and
updating the working copy from the root commit to a commit with
millions of files, we shouldn't have to walk the parts of the diff
that doesn't match the sparse patterns. However, we still do the full
walk because our `Tree::diff()` currently doesn't care about what the
matcher tells us to visit, it only filters out unwanted files after
visiting them. This commit fixes that for the special (but common)
case of matching nothing in a directory.
I tried also adding special handling for when the matcher says that we
should only visit a few entries, but it wasn't clearly better in the
cases I tested it on. I'll keep that patch around and might send it if
I find some cases where it helps.
The function only needs the `TreeValue` so it makes more sense this
way, I think. That will also let the caller keep the rest of the
`Conflict` value owned (though there is nothing but the `value` field
in it right now).
It took a while before I realized that conflicts could be modeled as
simple algebraic expressions with positive and negative terms (they
were modeled as recursive 3-way conflicts initially). We've been
thinking of them that way for a while now, so let's make the
`ConflictPart` name match that model.
Let's acknowledge everyone's contributions by replacing "Google LLC"
in the copyright header by "The Jujutsu Authors". If I understand
correctly, it won't have any legal effect, but maybe it still helps
reduce concerns from contributors (though I haven't heard any
concerns).
Google employees can read about Google's policy at
go/releasing/contributions#copyright.
There are no "non-normal" files, so "normal" is not needed. We have
symlinks and conflicts, but they are not files, so I think just "file"
is unambiguous.
I left `testutils::write_normal_file()` because there it's used to
mean "not executable file" (there's also a `write_executable_file()`).
I left `working_copy::FileType::Normal` since renaming `Normal` there
to `File` would also suggest we should rename `FileType`, and I don't
know what would be a better name for that type.
Tree merges can currently fail because of a failure to look up an
object, or because of a failure to read its contents. Both results in
`BackendError` because of a `impl From<std::io::Error> for
BackendError`. That's kind of correct in this case, but it wasn't
intentional (that impl was from `local_backend`), and we need to
making errors more specific for better error handling.
When a directory is missing in one merge input (base or one side), we
would consider that a merge conflict. This patch changes that so we
instead merge trees by treating the missing tree as empty.
We do it for all the other kinds of objects already. It's useful to
have the path for backends that store objects by path (we don't have
any such backends yet). I think the reason I didn't do it from the
beginning was because we had separate `RepoPath` types for files and
directories back then.
