Fix severe perf regression of complex nested function calls (#478)

* Add benchmark suite

* Add benchmark action

* Simplify benchmark

* Use simple heuristics to reduce expontential blowup

Author: JohnnyMorganz

.github/workflows/benchmark.yml

@@ -0,0 +1,33 @@
+name: Benchmark
+on:
+  push:
+    branches:
+      - master
+
+permissions:
+  contents: write
+  deployments: write
+
+jobs:
+  benchmark:
+    name: Run Benchmark
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      # - run: rustup toolchain update nightly && rustup default nightly
+      - name: Run benchmark
+        run: cargo bench | tee output.txt # +nightly
+
+      - name: Store benchmark result
+        uses: benchmark-action/github-action-benchmark@v1
+        with:
+          name: Rust Benchmark
+          tool: "cargo"
+          output-file-path: output.txt
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          auto-push: true
+          # Show alert with commit comment on detecting possible performance regression
+          alert-threshold: "200%"
+          comment-on-alert: true
+          fail-on-alert: true
+          alert-comment-cc-users: "@johnnymorganz"

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [**Luau**] Increased the shape size of the expression in a type assertion so that it will correctly hang if over width ([#466](https://github.com/JohnnyMorganz/StyLua/issues/466))
 - Fixed binary expression in a table field containing a comment being collapsed leading to malformed formatted ([#471](https://github.com/JohnnyMorganz/StyLua/issues/471))
 - Fixed end parentheses of a function call with a multiline comment internally being expanded onto a new line unnecessarily ([#473](https://github.com/JohnnyMorganz/StyLua/issues/473))
+- Fixed severe performance regression with complex nested function calls ([#477](https://github.com/JohnnyMorganz/StyLua/issues/477))
 
 ## [0.13.1] - 2022-04-11
 ### Fixed

Cargo.toml

@@ -60,3 +60,7 @@ harness = false
 [[bench]]
 name = "nested_tables"
 harness = false
+
+[[bench]]
+name = "docgen"
+harness = false

benches/docgen.lua

@@ -0,0 +1,86 @@
+-- https://github.com/neovim/nvim-lspconfig/blob/master/scripts/docgen.lua
+-- https://github.com/neovim/nvim-lspconfig/blob/master/LICENSE.md
+local preamble_parts = make_parts {
+	function()
+	  if docs.description and #docs.description > 0 then
+		return docs.description
+	  end
+	end,
+	function()
+	  local package_json_name = util.path.join(tempdir, template_name .. '.package.json')
+	  if docs.package_json then
+		if not util.path.is_file(package_json_name) then
+		  os.execute(string.format('curl -v -L -o %q %q', package_json_name, docs.package_json))
+		end
+		if not util.path.is_file(package_json_name) then
+		  print(string.format('Failed to download package.json for %q at %q', template_name, docs.package_json))
+		  os.exit(1)
+		  return
+		end
+		local data = fn.json_decode(readfile(package_json_name))
+		-- The entire autogenerated section.
+		return make_section(0, '\n', {
+		  -- The default settings section
+		  function()
+			local default_settings = (data.contributes or {}).configuration
+			if not default_settings.properties then
+			  return
+			end
+			-- The outer section.
+			return make_section(0, '\n', {
+			  'This server accepts configuration via the `settings` key.',
+			  '<details><summary>Available settings:</summary>',
+			  '',
+			  -- The list of properties.
+			  make_section(
+				0,
+				'\n\n',
+				sorted_map_table(default_settings.properties, function(k, v)
+				  local function tick(s)
+					return string.format('`%s`', s)
+				  end
+				  local function bold(s)
+					return string.format('**%s**', s)
+				  end
+
+				  -- https://github.github.com/gfm/#backslash-escapes
+				  local function excape_markdown_punctuations(str)
+					local pattern =
+					  '\\(\\*\\|\\.\\|?\\|!\\|"\\|#\\|\\$\\|%\\|\'\\|(\\|)\\|,\\|-\\|\\/\\|:\\|;\\|<\\|=\\|>\\|@\\|\\[\\|\\\\\\|\\]\\|\\^\\|_\\|`\\|{\\|\\\\|\\|}\\)'
+					return fn.substitute(str, pattern, '\\\\\\0', 'g')
+				  end
+
+				  -- local function pre(s) return string.format("<pre>%s</pre>", s) end
+				  -- local function code(s) return string.format("<code>%s</code>", s) end
+				  if not (type(v) == 'table') then
+					return
+				  end
+				  return make_section(0, '\n', {
+					'- ' .. make_section(0, ': ', {
+					  bold(tick(k)),
+					  function()
+						if v.enum then
+						  return tick('enum ' .. inspect(v.enum))
+						end
+						if v.type then
+						  return tick(table.concat(tbl_flatten { v.type }, '|'))
+						end
+					  end,
+					}),
+					'',
+					make_section(2, '\n\n', {
+					  { v.default and 'Default: ' .. tick(inspect(v.default, { newline = '', indent = '' })) },
+					  { v.items and 'Array items: ' .. tick(inspect(v.items, { newline = '', indent = '' })) },
+					  { excape_markdown_punctuations(v.description) },
+					}),
+				  })
+				end)
+			  ),
+			  '',
+			  '</details>',
+			})
+		  end,
+		})
+	  end
+	end,
+}

benches/docgen.rs

@@ -0,0 +1,22 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use stylua_lib::{format_code, Config, OutputVerification};
+
+pub fn format_docgen(c: &mut Criterion) {
+    c.bench_function("format docgen.lua", |b| {
+        b.iter(|| {
+            format_code(
+                black_box(include_str!("./docgen.lua")),
+                black_box(Config::default()),
+                black_box(None),
+                black_box(OutputVerification::None),
+            )
+        })
+    });
+}
+
+criterion_group! {
+    name = benches;
+    config = Criterion::default().sample_size(40);
+    targets = format_docgen
+}
+criterion_main!(benches);

src/formatters/functions.rs

@@ -184,9 +184,17 @@ fn function_args_multiline_heuristic(
 
     // Format all the arguments on an infinite width, so that we can prepare them and check to see whether they
     // need expanding. We will ignore punctuation for now
-    let first_iter_formatted_arguments = arguments
-        .iter()
-        .map(|argument| format_expression(ctx, argument, shape.with_infinite_width()));
+    let first_iter_formatted_arguments = arguments.iter().map(|argument| {
+        if shape.using_simple_heuristics() {
+            argument.to_owned()
+        } else {
+            format_expression(
+                ctx,
+                argument,
+                shape.with_simple_heuristics().with_infinite_width(),
+            )
+        }
+    });
 
     // Apply some heuristics to determine whether we should expand the function call
     let mut singleline_shape = shape + PAREN_LEN;

src/shape.rs

@@ -102,6 +102,9 @@ pub struct Shape {
     offset: usize,
     /// The maximum number of characters we want to fit on a line. This is inferred from the configuration
     column_width: usize,
+    /// Whether we should use simple heuristic checking.
+    /// This is enabled when we are calling within a heuristic itself, to reduce the exponential blowup
+    simple_heuristics: bool,
 }
 
 impl Shape {
@@ -111,6 +114,7 @@ impl Shape {
             indent: Indent::new(ctx),
             offset: 0,
             column_width: ctx.config().column_width,
+            simple_heuristics: false,
         }
     }
 
@@ -179,6 +183,19 @@ impl Shape {
         }
     }
 
+    /// Whether simple heuristics should be used when calculating formatting shape
+    /// This is to reduce the expontential blowup of discarded test formatting
+    pub fn using_simple_heuristics(&self) -> bool {
+        self.simple_heuristics
+    }
+
+    pub fn with_simple_heuristics(&self) -> Shape {
+        Self {
+            simple_heuristics: true,
+            ..*self
+        }
+    }
+
     /// Resets the offset for the shape
     pub fn reset(&self) -> Shape {
         Self { offset: 0, ..*self }