Basic concurrent checking (#13049)

Cargo.lock

@@ -1989,6 +1989,7 @@ dependencies = [
  "anyhow",
  "crossbeam",
  "notify",
+ "rayon",
  "red_knot_python_semantic",
  "ruff_cache",
  "ruff_db",
@@ -2147,6 +2148,7 @@ dependencies = [
  "criterion",
  "mimalloc",
  "once_cell",
+ "rayon",
  "red_knot_python_semantic",
  "red_knot_workspace",
  "ruff_db",

crates/red_knot_wasm/tests/api.rs

@@ -11,11 +11,11 @@ fn check() {
     };
     let mut workspace = Workspace::new("/", &settings).expect("Workspace to be created");
 
-    let test = workspace
+    workspace
         .open_file("test.py", "import random22\n")
         .expect("File to be opened");
 
-    let result = workspace.check_file(&test).expect("Check to succeed");
+    let result = workspace.check().expect("Check to succeed");
 
     assert_eq!(
         result,

crates/red_knot_workspace/Cargo.toml

@@ -22,6 +22,7 @@ ruff_text_size = { workspace = true }
 anyhow = { workspace = true }
 crossbeam = { workspace = true }
 notify = { workspace = true }
+rayon = { workspace = true }
 rustc-hash = { workspace = true }
 salsa = { workspace = true }
 tracing = { workspace = true }

crates/red_knot_workspace/src/db.rs

@@ -56,6 +56,8 @@ impl RootDatabase {
     }
 
     pub fn check_file(&self, file: File) -> Result<Vec<String>, Cancelled> {
+        let _span = tracing::debug_span!("check_file", file=%file.path(self)).entered();
+
         self.with_db(|db| check_file(db, file))
     }
 

crates/red_knot_workspace/src/workspace.rs

@@ -15,7 +15,8 @@ use ruff_db::{
 use ruff_python_ast::{name::Name, PySourceType};
 use ruff_text_size::Ranged;
 
-use crate::workspace::files::{Index, Indexed, PackageFiles};
+use crate::db::RootDatabase;
+use crate::workspace::files::{Index, Indexed, IndexedIter, PackageFiles};
 use crate::{
     db::Db,
     lint::{lint_semantic, lint_syntax},
@@ -190,23 +191,35 @@ impl Workspace {
     }
 
     /// Checks all open files in the workspace and its dependencies.
-    #[tracing::instrument(level = "debug", skip_all)]
-    pub fn check(self, db: &dyn Db) -> Vec<String> {
+    pub fn check(self, db: &RootDatabase) -> Vec<String> {
+        let workspace_span = tracing::debug_span!("check_workspace");
+        let _span = workspace_span.enter();
+
         tracing::debug!("Checking workspace");
+        let files = WorkspaceFiles::new(db, self);
+        let result = Arc::new(std::sync::Mutex::new(Vec::new()));
+        let inner_result = Arc::clone(&result);
 
-        let mut result = Vec::new();
+        let db = db.snapshot();
+        let workspace_span = workspace_span.clone();
 
-        if let Some(open_files) = self.open_files(db) {
-            for file in open_files {
-                result.extend_from_slice(&check_file(db, *file));
-            }
-        } else {
-            for package in self.packages(db) {
-                result.extend(package.check(db));
-            }
-        }
+        rayon::scope(move |scope| {
+            for file in &files {
+                let result = inner_result.clone();
+                let db = db.snapshot();
+                let workspace_span = workspace_span.clone();
 
-        result
+                scope.spawn(move |_| {
+                    let check_file_span = tracing::debug_span!(parent: &workspace_span, "check_file", file=%file.path(&db));
+                    let _entered = check_file_span.entered();
+
+                    let file_diagnostics = check_file(&db, file);
+                    result.lock().unwrap().extend(file_diagnostics);
+                });
+            }
+        });
+
+        Arc::into_inner(result).unwrap().into_inner().unwrap()
     }
 
     /// Opens a file in the workspace.
@@ -324,19 +337,6 @@ impl Package {
         index.insert(file);
     }
 
-    #[tracing::instrument(level = "debug", skip(db))]
-    pub(crate) fn check(self, db: &dyn Db) -> Vec<String> {
-        tracing::debug!("Checking package '{}'", self.root(db));
-
-        let mut result = Vec::new();
-        for file in &self.files(db) {
-            let diagnostics = check_file(db, file);
-            result.extend_from_slice(&diagnostics);
-        }
-
-        result
-    }
-
     /// Returns the files belonging to this package.
     pub fn files(self, db: &dyn Db) -> Indexed<'_> {
         let files = self.file_set(db);
@@ -384,9 +384,7 @@ impl Package {
 
 #[salsa::tracked]
 pub(super) fn check_file(db: &dyn Db, file: File) -> Vec<String> {
-    let path = file.path(db);
-    let _span = tracing::debug_span!("check_file", file=%path).entered();
-    tracing::debug!("Checking file '{path}'");
+    tracing::debug!("Checking file '{path}'", path = file.path(db));
 
     let mut diagnostics = Vec::new();
 
@@ -474,6 +472,73 @@ fn discover_package_files(db: &dyn Db, path: &SystemPath) -> FxHashSet<File> {
     files
 }
 
+#[derive(Debug)]
+enum WorkspaceFiles<'a> {
+    OpenFiles(&'a FxHashSet<File>),
+    PackageFiles(Vec<Indexed<'a>>),
+}
+
+impl<'a> WorkspaceFiles<'a> {
+    fn new(db: &'a dyn Db, workspace: Workspace) -> Self {
+        if let Some(open_files) = workspace.open_files(db) {
+            WorkspaceFiles::OpenFiles(open_files)
+        } else {
+            WorkspaceFiles::PackageFiles(
+                workspace
+                    .packages(db)
+                    .map(|package| package.files(db))
+                    .collect(),
+            )
+        }
+    }
+}
+
+impl<'a> IntoIterator for &'a WorkspaceFiles<'a> {
+    type Item = File;
+    type IntoIter = WorkspaceFilesIter<'a>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        match self {
+            WorkspaceFiles::OpenFiles(files) => WorkspaceFilesIter::OpenFiles(files.iter()),
+            WorkspaceFiles::PackageFiles(package_files) => {
+                let mut package_files = package_files.iter();
+                WorkspaceFilesIter::PackageFiles {
+                    current: package_files.next().map(IntoIterator::into_iter),
+                    package_files,
+                }
+            }
+        }
+    }
+}
+
+enum WorkspaceFilesIter<'db> {
+    OpenFiles(std::collections::hash_set::Iter<'db, File>),
+    PackageFiles {
+        package_files: std::slice::Iter<'db, Indexed<'db>>,
+        current: Option<IndexedIter<'db>>,
+    },
+}
+
+impl Iterator for WorkspaceFilesIter<'_> {
+    type Item = File;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            WorkspaceFilesIter::OpenFiles(files) => files.next().copied(),
+            WorkspaceFilesIter::PackageFiles {
+                package_files,
+                current,
+            } => loop {
+                if let Some(file) = current.as_mut().and_then(Iterator::next) {
+                    return Some(file);
+                }
+
+                *current = Some(package_files.next()?.into_iter());
+            },
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use ruff_db::files::system_path_to_file;

crates/red_knot_workspace/src/workspace/files.rs

@@ -158,9 +158,11 @@ impl Deref for Indexed<'_> {
     }
 }
 
+pub(super) type IndexedIter<'a> = std::iter::Copied<std::collections::hash_set::Iter<'a, File>>;
+
 impl<'a> IntoIterator for &'a Indexed<'_> {
     type Item = File;
-    type IntoIter = std::iter::Copied<std::collections::hash_set::Iter<'a, File>>;
+    type IntoIter = IndexedIter<'a>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.files.iter().copied()

crates/ruff_benchmark/Cargo.toml

@@ -37,13 +37,14 @@ name = "red_knot"
 harness = false
 
 [dependencies]
+codspeed-criterion-compat = { workspace = true, default-features = false, optional = true }
+criterion = { workspace = true, default-features = false }
 once_cell = { workspace = true }
+rayon = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 url = { workspace = true }
 ureq = { workspace = true }
-criterion = { workspace = true, default-features = false }
-codspeed-criterion-compat = { workspace = true, default-features = false, optional = true }
 
 [dev-dependencies]
 ruff_db = { workspace = true }

crates/ruff_benchmark/benches/red_knot.rs

@@ -1,5 +1,6 @@
 #![allow(clippy::disallowed_names)]
 
+use rayon::ThreadPoolBuilder;
 use red_knot_python_semantic::PythonVersion;
 use red_knot_workspace::db::RootDatabase;
 use red_knot_workspace::watch::{ChangeEvent, ChangedKind};
@@ -97,7 +98,25 @@ fn setup_case() -> Case {
     }
 }
 
+static RAYON_INITIALIZED: std::sync::Once = std::sync::Once::new();
+
+fn setup_rayon() {
+    // Initialize the rayon thread pool outside the benchmark because it has a significant cost.
+    // We limit the thread pool to only one (the current thread) because we're focused on
+    // where red knot spends time and less about how well the code runs concurrently.
+    // We might want to add a benchmark focusing on concurrency to detect congestion in the future.
+    RAYON_INITIALIZED.call_once(|| {
+        ThreadPoolBuilder::new()
+            .num_threads(1)
+            .use_current_thread()
+            .build_global()
+            .unwrap();
+    });
+}
+
 fn benchmark_incremental(criterion: &mut Criterion) {
+    setup_rayon();
+
     criterion.bench_function("red_knot_check_file[incremental]", |b| {
         b.iter_batched_ref(
             || {
@@ -134,6 +153,8 @@ fn benchmark_incremental(criterion: &mut Criterion) {
 }
 
 fn benchmark_cold(criterion: &mut Criterion) {
+    setup_rayon();
+
     criterion.bench_function("red_knot_check_file[cold]", |b| {
         b.iter_batched_ref(
             setup_case,