Avoid loading files for cached format results (#8134)

crates/ruff_cli/src/cache.rs

@@ -571,7 +571,6 @@ mod tests {
     use ruff_cache::CACHE_DIR_NAME;
     use ruff_linter::settings::flags;
     use ruff_linter::settings::types::UnsafeFixes;
-    use ruff_linter::source_kind::SourceKind;
     use ruff_python_ast::PySourceType;
     use ruff_workspace::Settings;
 
@@ -1061,7 +1060,6 @@ mod tests {
             format_path(
                 &file_path,
                 &self.settings.formatter,
-                &SourceKind::Python(std::fs::read_to_string(&file_path).unwrap()),
                 PySourceType::Python,
                 FormatMode::Write,
                 Some(cache),

crates/ruff_cli/src/commands/format.rs

@@ -131,18 +131,6 @@ pub(crate) fn format(
                         return None;
                     }
 
-                    // Extract the sources from the file.
-                    let unformatted = match SourceKind::from_path(path, source_type) {
-                        Ok(Some(source_kind)) => source_kind,
-                        Ok(None) => return None,
-                        Err(err) => {
-                            return Some(Err(FormatCommandError::Read(
-                                Some(path.to_path_buf()),
-                                err,
-                            )));
-                        }
-                    };
-
                     let package = path
                         .parent()
                         .and_then(|parent| package_roots.get(parent).copied())
@@ -155,15 +143,13 @@ pub(crate) fn format(
                             format_path(
                                 path,
                                 &resolved_settings.formatter,
-                                &unformatted,
                                 source_type,
                                 mode,
                                 cache,
                             )
                         }) {
                             Ok(inner) => inner.map(|result| FormatPathResult {
                                 path: resolved_file.path().to_path_buf(),
-                                unformatted,
                                 result,
                             }),
                             Err(error) => Err(FormatCommandError::Panic(
@@ -260,7 +246,6 @@ pub(crate) fn format(
 pub(crate) fn format_path(
     path: &Path,
     settings: &FormatterSettings,
-    unformatted: &SourceKind,
     source_type: PySourceType,
     mode: FormatMode,
     cache: Option<&Cache>,
@@ -277,8 +262,18 @@ pub(crate) fn format_path(
         }
     }
 
+    // Extract the sources from the file.
+    let unformatted = match SourceKind::from_path(path, source_type) {
+        Ok(Some(source_kind)) => source_kind,
+        // Non Python Jupyter notebook
+        Ok(None) => return Ok(FormatResult::Skipped),
+        Err(err) => {
+            return Err(FormatCommandError::Read(Some(path.to_path_buf()), err));
+        }
+    };
+
     // Format the source.
-    let format_result = match format_source(unformatted, source_type, Some(path), settings)? {
+    let format_result = match format_source(&unformatted, source_type, Some(path), settings)? {
         FormattedSource::Formatted(formatted) => match mode {
             FormatMode::Write => {
                 let mut writer = File::create(path).map_err(|err| {
@@ -300,7 +295,10 @@ pub(crate) fn format_path(
                 FormatResult::Formatted
             }
             FormatMode::Check => FormatResult::Formatted,
-            FormatMode::Diff => FormatResult::Diff(formatted),
+            FormatMode::Diff => FormatResult::Diff {
+                unformatted,
+                formatted,
+            },
         },
         FormattedSource::Unchanged => {
             if let Some(cache) = cache {
@@ -432,16 +430,21 @@ pub(crate) enum FormatResult {
     /// The file was formatted.
     Formatted,
     /// The file was formatted, [`SourceKind`] contains the formatted code
-    Diff(SourceKind),
+    Diff {
+        unformatted: SourceKind,
+        formatted: SourceKind,
+    },
     /// The file was unchanged, as the formatted contents matched the existing contents.
     Unchanged,
+
+    /// Skipped formatting because its an unformatted file format
+    Skipped,
 }
 
 /// The coupling of a [`FormatResult`] with the path of the file that was analyzed.
 #[derive(Debug)]
 struct FormatPathResult {
     path: PathBuf,
-    unformatted: SourceKind,
     result: FormatResult,
 }
 
@@ -463,15 +466,19 @@ impl<'a> FormatResults<'a> {
     fn any_formatted(&self) -> bool {
         self.results.iter().any(|result| match result.result {
             FormatResult::Formatted | FormatResult::Diff { .. } => true,
-            FormatResult::Unchanged => false,
+            FormatResult::Unchanged | FormatResult::Skipped => false,
         })
     }
 
     fn write_diff(&self, f: &mut impl Write) -> io::Result<()> {
         for result in self.results {
-            if let FormatResult::Diff(formatted) = &result.result {
+            if let FormatResult::Diff {
+                unformatted,
+                formatted,
+            } = &result.result
+            {
                 let text_diff =
-                    TextDiff::from_lines(result.unformatted.source_code(), formatted.source_code());
+                    TextDiff::from_lines(unformatted.source_code(), formatted.source_code());
                 let mut unified_diff = text_diff.unified_diff();
                 unified_diff.header(
                     &fs::relativize_path(&result.path),
@@ -502,9 +509,10 @@ impl<'a> FormatResults<'a> {
                     changed += 1;
                 }
                 FormatResult::Unchanged => unchanged += 1,
-                FormatResult::Diff(_) => {
+                FormatResult::Diff { .. } => {
                     changed += 1;
                 }
+                FormatResult::Skipped => {}
             }
         }