While playing with perf.data captured with "jj log", I noticed RepoPath::join()
has measurable cost. The first half is small alloc()s for Vec and Strings, and
the latter is realloc() on Vec::push(). Removing realloc() is easy, so let's
do that.
We already have the new `Conflict::from_backend_conflict()` for
converting from a `backend::Conflict`, but we model conflicts in a
similar way in at least `RefTarget`. I'd like to be able to use
`conflicts::Conflict` there too. To prepare for that, let's extract
generic methods from `Conflict::from_backend_conflict()` and
`Conflict::to_backend_conflict()`.
I'm not sure I'll get around to making `RefTarget` use `Conflict` but
this commit seems like nice cleanup either way. It makes the tests
simpler if nothing else.
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.
For tree-level conflicts (#1624), I plan to remove `ConflictId`
completely. This commit removes `ConflictId` from
`update_conflict_from_content()` by instead making it take a
`Conflict<Option<TreeValue>>` and return a possibly different such
value.
I made the call site in `working_copy` avoid writing the conflict to
the store if it's unchanged, but I didn't make the same optimization
in `merge_tools` becuase it's much more likely to have changed there.
Use `br@git` instead.
Before, if there is not a local branch `br`, jj tried to resolve
it as a git ref `refs/heads/br`. Unchanged from before, `br` can
still be resolved as a tag `refs/tag/br`.
This doesn't change the way @git branches are stored in `git_refs` as opposed
to inside `BranchTarget` like normal remote-tracking branches. There are
subtle differences in behavior with e.g. `jj branch forget` and I'm not sure
how easy it is to rewrite `jj git import/export` to support a different
way of storage.
I've decided to call these "local-git tracking branches" since they track
branches in the local git repository. "local git-tracking" branches sounds a
bit more natural, but these could be confused with there are no remote
git-tracking branches. If one had the idea these might exist, they would be
confused with remote-tracking branches in the local git repo.
This addresses a portion of #1666
Suppose the operation log is mostly linear, this means "jj op log" iterator
won't look ahead more than one entry.
Another idea is to either add a "generation" number to operation data, or
build index of operations. Since we'll eventually add GC command, I don't
think op index would be required. I think readdir() is good enough to resolve
hex prefix against ~10k entries.
For now, walk_ancestors() is a free function. If we add Repo-like abstraction
over OpStore + OpHeadsStore, this function will probably be migrated there.
The idea is that the DAG can be split at single fork point while walking
chronologically, and run DFS-based topological sort for each sub graph.
This works well for operation log.
We could also build a topo-sort stack while splitting, but we couldn't detect
cycles in that way. It would also be quite expensive on pessimistic cases.
I added a function for updating the description on an existing
transaction. That way we can create the transaction earlier. I'll try
to make `--change` and `--branch` not mutually exclusive next.
Currently, if the user modifies a modify/delete conflict, we always
consider the result resolved. That happens because we materialize the
missing side of the conflict as an empty string but when we parse the
conflict, we expect only the number of sides in the input
conflict. For example, if the input is a regular modify/delete
conflict with one remove and one add, the materialized markers will
have one remove and two adds (one of them empty), but when we try to
parse it, we expect one remove and only one add. When we fail to parse
it, we consider it resolved.
This commit fixes the bug by using
`conflicts::Conflict<Option<TreeValue>>` and keeping track of which
sides were supposed to be empty. We could have fixed the bug without
switching to `conflicts::Conflict`, but we want to switch anyway, and
the fix happens naturally when switching.
For support for tree-level conflicts (#1624), I'm probably going to
introduce a `MergedTree` type representing a set of trees to
merge. That will be similar to `Tree`, but instead of having values of
type `TreeValue`, it will have values that can represent a single
state or a conflict. The `TreeValue` type itself will eventually lose
its `Conflict` variant.
To prepare for that, this commit introduces a `Conflict<T>` type. That
type is intended to be close to what the future
`MergedTree::path_value()`, `MergedTree::entries()`, etc. The next few
commits will replace most current uses of `backend::Conflict` by this
new `conflicts::Conflict` type. They will use `Option<TreeValue>` as
type parameter. Unlike the current `backend::Conflict` type, the
explicit tracking of `None` values will let us better preserve the
ordering and tying it to the tree-level conflict's order.
Suppose many override entries share the same parent directories, it should
be cheaper to look up the tree_cache from leaf than root. I also think
recursion is easier to follow than for loop.
