Fine. Optimize diagnostics reuse with an API signature shortcut

Previously, reusing cached diagnostics always required validating the
fine-grained `RequirementsManifest`. While effective (save `6000 ms` by
not analyzing files when API changed), this process incurred significant
overhead even for changes that did not affect a library's public API,
such as modifying a method body. In these scenarios, the check could
nearly double the total analysis time (add `110 ms`).

This change introduces a two-tiered validation system to improve
performance and refactors diagnostics handling:

- A new `LibraryDiagnosticsBundle` class is extracted to better
  encapsulate a library's diagnostics and its requirements.

- A coarse-grained API signature check now acts as a fast-path
  shortcut. If a library's API signature is unchanged, its cached
  diagnostics are reused immediately, bypassing the more expensive
  manifest validation. The full manifest is only checked if this
  shortcut fails.

Additionally, the key for the diagnostics bundle is now cached on the
`LibraryFileKind` object itself. This prevents recomputing the key's
hash upon every access, further improving performance, about `16 ms` for
`1600` files in the analyzer itself.

With these changes the overhead of producing diagnostics is under `1
ms`. There is still some overhead of about `30 ms` in re-loading library
summaries, I will address this separately.

Change-Id: Iec884b8e0311e20965c7cde6d8cbae42b513a107
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/447520
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
6 files changed
tree: 14c815e8f18ff4b7111a18d3439caacab768347c
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. docs/
  6. pkg/
  7. runtime/
  8. samples/
  9. sdk/
  10. tests/
  11. third_party/
  12. tools/
  13. utils/
  14. .clang-format
  15. .gitattributes
  16. .gitconfig
  17. .gitignore
  18. .gn
  19. .mailmap
  20. .style.yapf
  21. AUTHORS
  22. BUILD.gn
  23. CHANGELOG.md
  24. codereview.settings
  25. CONTRIBUTING.md
  26. DEPS
  27. LICENSE
  28. OWNERS
  29. PATENT_GRANT
  30. PRESUBMIT.py
  31. pubspec.yaml
  32. README.dart-sdk
  33. README.md
  34. sdk.code-workspace
  35. sdk_args.gni
  36. sdk_packages.yaml
  37. SECURITY.md
  38. WATCHLISTS
README.md

Dart

An approachable, portable, and productive language for high-quality apps on any platform

Dart is:

  • Approachable: Develop with a strongly typed programming language that is consistent, concise, and offers modern language features like null safety and patterns.

  • Portable: Compile to ARM, x64, or RISC-V machine code for mobile, desktop, and backend. Compile to JavaScript or WebAssembly for the web.

  • Productive: Make changes iteratively: use hot reload to see the result instantly in your running app. Diagnose app issues using DevTools.

Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:

  • Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

  • Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).

Dart platforms illustration

License & patents

Dart is free and open source.

See LICENSE and PATENT_GRANT.

Using Dart

Visit dart.dev to learn more about the language, tools, and to find codelabs.

Browse pub.dev for more packages and libraries contributed by the community and the Dart team.

Our API reference documentation is published at api.dart.dev, based on the stable release. (We also publish docs from our beta and dev channels, as well as from the primary development branch).

Building Dart

If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.

There are more documents in our repo at docs.

Contributing to Dart

The easiest way to contribute to Dart is to file issues.

You can also contribute patches, as described in Contributing.

Roadmap

Future plans for Dart are included in the combined Dart and Flutter roadmap on the Flutter wiki.