I don't know if we ever resolve revsets in a mutable repo, but now
that we can get a change id index from a revset, it's easier to
implement this functionality that way.
This replaces the direct use of `IdIndex` in `ReadonlyRepo` by use of
`Revset::change_id_index()`.
I made the `Index` trait require `Send` and `Sync` in order to be able
to store an instance of it in `ReadonlyRepo` (via `ChangeIdIndex`) and
still have that be `Send` and `Sync`. We could alternatively store the
`ChangeIdIndex` in a `Mutex`. Now that will be up to the
`ChangeIdIndex` instead.
I'd like to be able to pass a `self` of `type `&ReadonlyRepo` to
functions that take a `&dyn Repo`. For that, we need `ReadonlyRepo`
itself to implement `Repo` instead of having `Arc<ReadonlyRepo>`
implement it. I could have solved it in a different way, but the `Arc`
requirement seems like an unnecessary constraint.
The functions resolving a change id to commits currently return a
`Vec<IndexEntry>`. We want to avoid depending on `IndexEntry` and we
only need the commit ids here.
This is yet another step towards making the index pluggable. The
`IndexStore` trait seems reasonable after this commit. There's still a
lot of work to remove `IndexPosition` from the `Index` trait.
I didn't make `ReadonlyIndex` extend `Index` because it needed an
`as_index()` to convert to `&dyn Index` trait object
anyway. Separating the types also gives us flexibility to implement
the two traits on different types.
Not all index implementations may want to store the readonly index
implementation in an Arc. Exposing the Arc in the interface is also
problematic because `Arc<IndexImpl>` cannot be cast to `Arc<dyn
Index>`.
These two files are closely related, and `Index` and `IndexStore` are
expected to be customized together, so it seems better to keep them in
a single file.
This is another step towards allowing a custom `jj` binary to have its
own index type. We're going to have a server-backed index
implementation at Google, for example.
This is a step towards making the index storage pluggable. The
interface will probably change a bit soon, but let's start with
functions that match the current implementation.
I called the current implementation the `DefaultIndexStore`. Calling
it `SimpleIndexStore` (like `SimpleOpStore` and `SimpleOpHeadsStore`)
didn't seem accurate.
It makes the APIs much simpler if we don't have to pass in information
about the initial operation when we create the `OpHeadsStore`. It also
makes the alternative `OpHeadsStore` implementations simpler since we
move some logic into a shared location (`ReadonlyRepo::init()`).
This effectively undoes ec07104126. Maybe some further refactoring
made it possible to move it back as I'm doing in this commit?
I'm about to make `RepoLoader::init()` return a `Result`, and I don't
want to have to wrap that in a new error in
`ReadonlyRepo::load_at_head()` since that's only used in tests.
This is just a little preparation for extracting a `Repo` trait that's
implemented by both `ReadonlyRepo` and `MutableRepo`. The `index()`
function in that trait will of course have to return the same type in
both implementations, and that type will be `&dyn Index`.
Even though we don't know the details yet, we know that we want to
make the index pluggable like the commit and opstore
backends. Defining a trait for it should be a good step. We can refine
the trait later.
Our internal backend at Google uses a 32-byte change id, so I'd like
to make the backend able to decide the length. To start with, let's
make the backend able to decide what the root change id should
be. That's consistent with how we already let the backend decide what
the root commit id should be.
Git's HEAD ref is similar to other refs and can logically have
conflicts just like the other refs in `git_refs`. As with the other
refs, it can happen if you run concurrent commands importing two
different updates from Git. So let's treat `git_head` the same as
`git_refs` by making it an `Option<RefTarget>`.
I would expect `Commit::is_empty()` to check if the commit is empty in
our usual sense, i.e. that there are no changes compared to the
auto-merged parents. However, it would return `false` for any merge
commit (and for the root commit). Since we only use it in one place,
let's inline it there. The use there does seem reasonable, because
it's about abandoning an "uninteresting" working-copy commit.
revset::resolve_change_id() for ReadonlyRepo will be replaced with this
implementation. This doesn't mean revset query will speed up. A trivial
query will become slower due to the initialization cost of the change id
index. "jj log -r hex" will get faster since we have to pay the cost anyway.
Benchmark numbers (against my "linux" repo):
Command:
hyperfine --warmup 3 --runs 20 \
"jj log -r $hex -T '' --no-commit-working-copy --no-graph"
Linear search (e874570947):
Time (mean ± σ): 223.9 ms ± 16.2 ms [User: 181.2 ms, System: 42.7 ms]
Range (min … max): 207.7 ms … 247.6 ms 50 runs
Building IdIndex:
Time (mean ± σ): 855.0 ms ± 21.7 ms [User: 788.4 ms, System: 66.6 ms]
Range (min … max): 822.6 ms … 927.5 ms 50 runs
Building IdIndex, but hacked to store SmallVec<[u8; 20]>:
Time (mean ± σ): 406.1 ms ± 15.9 ms [User: 354.1 ms, System: 52.0 ms]
Range (min … max): 382.2 ms … 428.6 ms 50 runs
For my "jj" work repo, changes are < ~1ms.
I've preferred "working-copy commit" over "checkout" for a while
because I think it's clearer, but there were lots of places still
using "checkout". I've left "checkout" in places where it refers to
the action of updating the working copy or the working-copy commit.
Since this function depends on both index and view, it can't be moved to
one of the storage objects. If we go forward with this approach, some
revset::resolve_*() functions will also be migrated to RepoRef.
This patch slightly changes the function name since a "prefix" might have
various meanings.
This should fix the panic in the case reported in #1107. It's a bit
hard to reproduce because we normally notice the missing commit when
we snapshot the working copy, but it's possible to reproduce it using
`--no-commit-working-copy`.
I suspect the added test is too brittle because it checks the exact
error message. On the other hand, it might be useful to have one test
case like this so we catch accidental changes in the format.
Since IdIndex is immutable, we don't need fast insertion provided by BTreeMap.
Let's simply use Vec for some speed up. More importantly, this allows us to
store multiple (ChangeId, CommitId) pairs for the same change id, and will
unblock the use of IdIndex in revset::resolve_symbol().
Some benchmark numbers (against my "linux" repo) follow.
Command:
hyperfine --warmup 3 "jj log -r master \
-T 'commit_id.short_prefix_and_brackets()' \
--no-commit-working-copy --no-graph"
Original:
Time (mean ± σ): 1.892 s ± 0.031 s [User: 1.800 s, System: 0.092 s]
Range (min … max): 1.833 s … 1.935 s 10 runs
This commit:
Time (mean ± σ): 867.5 ms ± 2.7 ms [User: 809.9 ms, System: 57.7 ms]
Range (min … max): 862.3 ms … 871.0 ms 10 runs
