ruff server: Resolve configuration for each document individually (#…

…10950)

## Summary

Configuration is no longer the property of a workspace but rather of
individual documents. Just like the Ruff CLI, each document is
configured based on the 'nearest' project configuration. See [the Ruff
documentation](https://docs.astral.sh/ruff/configuration/#config-file-discovery)
for more details.

To reduce the amount of times we resolve configuration for a file, we
have an index for each workspace that stores a reference-counted pointer
to a configuration for a given folder. If another file in the same
folder is opened, the configuration is simply re-used rather than us
re-resolving it.

## Guide for reviewing

The first commit is just the restructuring work, which adds some noise
to the diff. If you want to quickly understand what's actually changed,
I recommend looking at the two commits that come after it.
f7c073d makes configuration a property
of `DocumentController`/`DocumentRef`, moving it out of `Workspace`, and
it also sets up the `ConfigurationIndex`, though it doesn't implement
its key function, `get_or_insert`. In the commit after it,
fc35618, we implement `get_or_insert`.

## Test Plan

The best way to test this would be to ensure that the behavior matches
the Ruff CLI. Open a project with multiple configuration files (or add
them yourself), and then introduce problems in certain files that won't
show due to their configuration. Add those same problems to a section of
the project where those rules are run. Confirm that the lint rules are
run as expected with `ruff check`. Then, open your editor and confirm
that the diagnostics shown match the CLI output.

As an example - I have a workspace with two separate folders, `pandas`
and `scipy`. I created a `pyproject.toml` file in `pandas/pandas/io` and
a `ruff.toml` file in `pandas/pandas/api`. I changed the `select` and
`preview` settings in the sub-folder configuration files and confirmed
that these were reflected in the diagnostics. I also confirmed that this
did not change the diagnostics for the `scipy` folder whatsoever.

crates/ruff_server/Cargo.toml

@@ -35,6 +35,7 @@ rustc-hash = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 tracing = { workspace = true }
+walkdir = { workspace = true }
 
 [dev-dependencies]
 insta = { workspace = true }

crates/ruff_server/src/server/api/notifications/did_change_watched_files.rs

@@ -19,7 +19,7 @@ impl super::SyncNotificationHandler for DidChangeWatchedFiles {
     ) -> Result<()> {
         for change in params.changes {
             session
-                .reload_configuration(&change.uri)
+                .reload_settings(&change.uri)
                 .with_failure_code(lsp_server::ErrorCode::InternalError)?;
         }
         Ok(())

crates/ruff_server/src/server/api/requests/code_action.rs

@@ -105,7 +105,7 @@ fn fix_all(snapshot: &DocumentSnapshot) -> crate::Result<CodeActionOrCommand> {
                 document,
                 snapshot.resolved_client_capabilities(),
                 snapshot.url(),
-                &snapshot.configuration().linter,
+                &snapshot.settings().linter,
                 snapshot.encoding(),
                 document.version(),
             )?),
@@ -140,7 +140,7 @@ fn organize_imports(snapshot: &DocumentSnapshot) -> crate::Result<CodeActionOrCo
                 document,
                 snapshot.resolved_client_capabilities(),
                 snapshot.url(),
-                &snapshot.configuration().linter,
+                &snapshot.settings().linter,
                 snapshot.encoding(),
                 document.version(),
             )?),

crates/ruff_server/src/server/api/requests/code_action_resolve.rs

@@ -45,7 +45,7 @@ impl super::BackgroundDocumentRequestHandler for CodeActionResolve {
                     document,
                     snapshot.resolved_client_capabilities(),
                     snapshot.url(),
-                    &snapshot.configuration().linter,
+                    &snapshot.settings().linter,
                     snapshot.encoding(),
                     document.version(),
                 )
@@ -56,7 +56,7 @@ impl super::BackgroundDocumentRequestHandler for CodeActionResolve {
                     document,
                     snapshot.resolved_client_capabilities(),
                     snapshot.url(),
-                    &snapshot.configuration().linter,
+                    &snapshot.settings().linter,
                     snapshot.encoding(),
                     document.version(),
                 )

crates/ruff_server/src/server/api/requests/diagnostic.rs

@@ -22,7 +22,7 @@ impl super::BackgroundDocumentRequestHandler for DocumentDiagnostic {
         let diagnostics = if snapshot.client_settings().lint() {
             crate::lint::check(
                 snapshot.document(),
-                &snapshot.configuration().linter,
+                &snapshot.settings().linter,
                 snapshot.encoding(),
             )
         } else {

crates/ruff_server/src/server/api/requests/execute_command.rs

@@ -64,7 +64,7 @@ impl super::SyncRequestHandler for ExecuteCommand {
                 Command::FixAll => {
                     let edits = super::code_action_resolve::fix_all_edit(
                         snapshot.document(),
-                        &snapshot.configuration().linter,
+                        &snapshot.settings().linter,
                         snapshot.encoding(),
                     )
                     .with_failure_code(ErrorCode::InternalError)?;
@@ -83,7 +83,7 @@ impl super::SyncRequestHandler for ExecuteCommand {
                 Command::OrganizeImports => {
                     let edits = super::code_action_resolve::organize_imports_edit(
                         snapshot.document(),
-                        &snapshot.configuration().linter,
+                        &snapshot.settings().linter,
                         snapshot.encoding(),
                     )
                     .with_failure_code(ErrorCode::InternalError)?;

crates/ruff_server/src/server/api/requests/format.rs

@@ -26,7 +26,7 @@ impl super::BackgroundDocumentRequestHandler for Format {
 pub(super) fn format_document(snapshot: &DocumentSnapshot) -> Result<super::FormatResponse> {
     let doc = snapshot.document();
     let source = doc.contents();
-    let formatted = crate::format::format(doc, &snapshot.configuration().formatter)
+    let formatted = crate::format::format(doc, &snapshot.settings().formatter)
         .with_failure_code(lsp_server::ErrorCode::InternalError)?;
     // fast path - if the code is the same, return early
     if formatted == source {

crates/ruff_server/src/server/api/requests/format_range.rs

@@ -22,7 +22,7 @@ impl super::BackgroundDocumentRequestHandler for FormatRange {
         let index = document.index();
         let range = params.range.to_text_range(text, index, snapshot.encoding());
         let formatted_range =
-            crate::format::format_range(document, &snapshot.configuration().formatter, range)
+            crate::format::format_range(document, &snapshot.settings().formatter, range)
                 .with_failure_code(lsp_server::ErrorCode::InternalError)?;
         Ok(Some(vec![types::TextEdit {
             range: formatted_range