perf(lsp): optimize formatting minified files (denoland#20829)

cli/lsp/language_server.rs

@@ -1651,11 +1651,11 @@ impl Inner {
  }
 
  // spawn a blocking task to allow doing other work while this is occurring
- let format_result = deno_core::unsync::spawn_blocking({
+ let text_edits = deno_core::unsync::spawn_blocking({
  let fmt_options = self.fmt_options.options.clone();
  let document = document.clone();
  move || {
- match document.maybe_parsed_source() {
+ let format_result = match document.maybe_parsed_source() {
  Some(Ok(parsed_source)) => {
  format_parsed_source(&parsed_source, &fmt_options)
  }
@@ -1672,26 +1672,24 @@ impl Inner {
  // it's not a js/ts file, so attempt to format its contents
  format_file(&file_path, &document.content(), &fmt_options)
  }
+ };
+ match format_result {
+ Ok(Some(new_text)) => Some(text::get_edits(
+ &document.content(),
+ &new_text,
+ document.line_index().as_ref(),
+ )),
+ Ok(None) => Some(Vec::new()),
+ Err(err) => {
+ lsp_warn!("Format error: {:#}", err);
+ None
+ }
  }
  }
  })
  .await
  .unwrap();
 
- let text_edits = match format_result {
- Ok(Some(new_text)) => Some(text::get_edits(
- &document.content(),
- &new_text,
- document.line_index().as_ref(),
- )),
- Ok(None) => Some(Vec::new()),
- Err(err) => {
- // TODO(lucacasonato): handle error properly
- lsp_warn!("Format error: {:#}", err);
- None
- }
- };
-
  self.performance.measure(mark);
  if let Some(text_edits) = text_edits {
  if text_edits.is_empty() {

cli/lsp/text.rs

@@ -210,6 +210,18 @@ pub fn get_edits(a: &str, b: &str, line_index: &LineIndex) -> Vec<TextEdit> {
  if a == b {
  return vec![];
  }
+ // Heuristic to detect things like minified files. `diff()` is expensive.
+ if b.chars().filter(|c| *c == '\n').count()
+ > line_index.utf8_offsets.len() * 3
+ {
+ return vec![TextEdit {
+ range: lsp::Range {
+ start: lsp::Position::new(0, 0),
+ end: line_index.position_utf16(TextSize::from(a.len() as u32)),
+ },
+ new_text: b.to_string(),
+ }];
+ }
  let chunks = diff(a, b);
  let mut text_edits = Vec::<TextEdit>::new();
  let mut iter = chunks.iter().peekable();