feat(rust/watch): handle bulk-change by hyf0 · Pull Request #8466 · rolldown/rolldown

hyf0 · 2026-02-25T16:45:18Z

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hyf0 · 2026-02-25T16:45:45Z

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Copilot

Pull request overview

This PR optimizes the watcher's bulk file change handling by replacing the O(n²) deduplication approach with an O(1) FxIndexMap-based solution. Previously, each file change triggered an individual state transition with vector-based deduplication; now batches of changes are processed together with a single state transition, significantly improving performance for scenarios like git checkout that generate thousands of file events.

Changes:

Replace Vec<FileChangeEvent> with FxIndexMap<String, WatcherChangeKind> for O(1) deduplication by path
Rename on_file_change to on_file_changes to accept batches of changes
Update state machine to perform a single state transition per batch instead of per-file transitions

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
meta/design/watch-mode.md	Updated documentation to reflect completed bulk-change optimization and FxIndexMap usage
crates/rolldown_watcher/src/watcher_state.rs	Refactored state machine to use FxIndexMap for change storage and batch processing
crates/rolldown_watcher/src/watch_coordinator.rs	Updated coordinator to work with batched file changes and FxIndexMap

Comments suppressed due to low confidence (1)

crates/rolldown_watcher/src/watcher_state.rs:192

Consider adding test coverage for the edge case where on_file_changes is called with an empty Vec. This would verify the behavior when no file changes are provided, which relates to the potential issue where empty entries could cause unnecessary state transitions or timer resets.

  #[test]
  fn test_batch_deduplicates_within_single_call() {
    let state = WatcherState::Idle;
    let entries = vec![
      FileChangeEvent::new("test.js".into(), WatcherChangeKind::Create),
      FileChangeEvent::new("test.js".into(), WatcherChangeKind::Update),
    ];
    let state = state.on_file_changes(entries, default_duration());

    if let WatcherState::Debouncing { changes, .. } = state {
      assert_eq!(changes.len(), 1);
      assert_eq!(changes["test.js"], WatcherChangeKind::Update);
    } else {
      panic!("Expected Debouncing state");
    }
  }

crates/rolldown_watcher/src/watcher_state.rs

meta/design/watch-mode.md

github-actions · 2026-02-25T17:05:51Z

Benchmarks Rust

target: main(b44f77d)
pr: 02-26-feat_rust_watch_handle_bulk-change(7a134b9)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00     78.6±1.36ms        ? ?/sec    1.00     78.3±1.27ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.00     86.8±1.64ms        ? ?/sec    1.01     87.5±2.26ms        ? ?/sec
bundle/bundle@rome_ts                                        1.00    159.3±4.63ms        ? ?/sec    1.00    159.5±3.60ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    176.5±3.74ms        ? ?/sec    1.01    177.7±3.42ms        ? ?/sec
bundle/bundle@threejs                                        1.00     72.1±2.57ms        ? ?/sec    1.00     71.8±1.17ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     79.9±1.48ms        ? ?/sec    1.00     79.8±0.90ms        ? ?/sec
bundle/bundle@threejs10x                                     1.00    755.5±5.32ms        ? ?/sec    1.00    758.0±7.14ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00    866.3±6.16ms        ? ?/sec    1.00    866.2±6.96ms        ? ?/sec
scan/scan@rome_ts                                            1.00     76.3±1.91ms        ? ?/sec    1.01     77.0±1.52ms        ? ?/sec
scan/scan@threejs                                            1.01     27.5±1.61ms        ? ?/sec    1.00     27.2±0.39ms        ? ?/sec
scan/scan@threejs10x                                         1.00    266.8±2.86ms        ? ?/sec    1.00    266.6±2.87ms        ? ?/sec

crates/rolldown_watcher/src/watcher_state.rs

netlify · 2026-03-01T12:27:00Z

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Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

crates/rolldown_watcher/src/watcher_state.rs

crates/rolldown_watcher/src/watch_coordinator.rs

meta/design/watch-mode.md

hyf0 · 2026-03-01T16:18:39Z

Merge activity

Mar 1, 4:18 PM UTC: The merge label 'graphite: merge-when-ready' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Mar 1, 4:28 PM UTC: hyf0 added this pull request to the Graphite merge queue.
Mar 1, 4:39 PM UTC: Merged by the Graphite merge queue.

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.

@IWANABETHATGUY

## [1.0.0-rc.7] - 2026-03-05 ⚡ Smarter Code Generation Defaults - DCE-only minification and smart constant inlining are now enabled by default - Produces cleaner, smaller output bundles without requiring explicit configuration 💡 LLM-Friendly Bundle Analyzer Reports - New markdown output format for the bundle analyzer plugin with bundle summaries, module graphs, dependency chains, and optimization suggestions - Optimization suggestions now also recommend using the entriesAware option when common chunks contain modules only reachable from specific entries ### 💥 BREAKING CHANGES - enable minify: 'dce-only' by default (#8465) by @IWANABETHATGUY - settings `inlineConst: { mode: 'smart', pass: 1}` by default (#8444) by @IWANABETHATGUY ### 🚀 Features - binding: add original getter to BindingMagicString (#8533) by @IWANABETHATGUY - native-magic-string: add `offset` property support (#8531) by @IWANABETHATGUY - add `output.strict` option to control `"use strict"` directive emission (#8489) by @Copilot - watch: expose `watcher.compareContentsForPolling` (#8526) by @hyf0 - watch: use new watcher to support watch mode (#8475) by @hyf0 - rust/watch: handle bulk-change (#8466) by @hyf0 - add LLM-friendly markdown output format to bundle analyzer plugin (#8242) by @IWANABETHATGUY ### 🐛 Bug Fixes - expose `plugins` on `NormalizedInputOptions` for `buildStart` hook (#8521) by @Copilot - only uppercase facade symbols in JSX preserve mode (#8519) by @IWANABETHATGUY - binding: export BindingResult in generated dts header (#8537) by @minsoo-web - pre-resolve paths option to avoid `invoke_sync` deadlock (#8518) by @IWANABETHATGUY - remove debug-only jsx_preset and UntranspiledSyntaxError (#8511) by @IWANABETHATGUY - apply `topLevelVar` to exported `const`/`let` declarations (#8507) by @IWANABETHATGUY - rolldown_plugin_vite_web_worker_post: avoid replacing `new.target` (#8488) by @sapphi-red - update copyright year to 2026 (#8486) by @maciekzygmunt ### 🚜 Refactor - rust: use Oxc's SymbolFlags::ConstVariable instead of custom IsConst flag (#8543) by @Dunqing - rust: remove FacadeScoping, use Scoping::create_symbol for facade symbols (#8540) by @Dunqing - rust/watch: remove hacky `reset_closed_for_watch_mode` (#8530) by @hyf0 - binding: return &str instead of String in filename() getter (#8534) by @IWANABETHATGUY - rust: remove old watch mode implementation (#8525) by @hyf0 - rust/watch: simply watch logic in the binding layer (#8516) by @hyf0 - rust/watch: tweak struct/function names (#8464) by @hyf0 ### 📚 Documentation - explain how external modules work in rolldown (#8457) by @sapphi-red - add some diagrams using graphviz (#8499) by @sapphi-red - use `vitepress-plugin-graphviz` (#8498) by @sapphi-red - list s390x/ppc64le prebuilt binaries (#8495) by @crusty-voidzero - fix error type for `RolldownBuild.generate` and others (#8490) by @sapphi-red ### ⚡ Performance - string_wizard: reduce allocations and add ASCII fast paths (#8541) by @IWANABETHATGUY - use IndexBitSet to replace IndexVec<XXXIdx, bool> for module/stmt inclusion tracking (#8503) by @IWANABETHATGUY - plugin: use IndexBitSet to optimize skipped plugins checking (#8497) by @ShroXd - rust/tla: skip compute_tla if there is no module use TLA (#8487) by @ShroXd ### 🧪 Testing - node/watch: make watch tests run in concurrent and retry-able (#8512) by @hyf0 - add test case for static flag tree-shaking (#8476) by @IWANABETHATGUY - migrate post-banner sourcemap-with-shebang to Rust (#8477) by @Copilot ### ⚙️ Miscellaneous Tasks - vscode: `formatOnSave` for markdown files using oxc formatter (#8536) by @minsoo-web - deps: update test262 submodule for tests (#8528) by @sapphi-red - remove `retry` workaround from output paths test fixtures (#8520) by @Copilot - docs: add Shuyuan Wang (h-a-n-a) and remove from acknowledgements (#8509) by @Copilot - consolidate top_level_var test cases using configVariants (#8508) by @IWANABETHATGUY - add s390x and ppc64le linux gnu targets (#8493) by @Brooooooklyn ### ◀️ Revert - fix(rolldown): increase tokio blocking threads size for watch mode (#8517) by @hyf0 ### ❤️ New Contributors * @minsoo-web made their first contribution in [#8536](#8536) * @crusty-voidzero made their first contribution in [#8495](#8495) * @maciekzygmunt made their first contribution in [#8486](#8486) Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>

hyf0 marked this pull request as ready for review February 25, 2026 16:45

Copilot AI review requested due to automatic review settings February 25, 2026 16:45

hyf0 mentioned this pull request Feb 25, 2026

refactor(rust/watch): tweak struct/function names #8464

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feat(watch): use new watcher to support watch mode #8475

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test(node/watch): make watch tests run in concurrent and retry-able #8512

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feat(rust/watch): handle bulk-change (#8466)

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feat(rust/watch): handle bulk-change#8466

feat(rust/watch): handle bulk-change#8466
graphite-app[bot] merged 1 commit intomainfrom
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