Konstantin Shcheglov
9052ec70ed
Introduce a fast-path in fine-grained dependency validation by comparing
a precomputed per-library hash before doing field-by-field checks. When
the recorded hash matches the current
LibraryManifest.hashForRequirements, we skip detailed validation for
that library; otherwise we fall back to the existing thorough
comparisons.
Why
---
Validating RequirementsManifest.isSatisfied() was spending time
walking multiple fields and maps even when nothing changed. The new hash
captures exactly the manifest parts that the validator reads, so
equality implies the same outcome. This keeps correctness while
dramatically reducing the common-case cost.
What changed
------------
- Add LibraryRequirements.hashForRequirements and persist it in the
binary format (read/write).
- Initialize per-library requirements from the current manifest via
LibraryRequirements.fromManifest(), capturing the hash and exportMapId.
- Extend RequirementsManifest.isSatisfied() to:
* short-circuit per-library checks when hashes match,
* record lightweight perf counters ("libHash"/"libDetails" and
"libsHash"/"libsDetails") via OperationPerformanceImpl.
- Thread the new performance parameter through callers:
* AnalysisDriver._getLibraryDiagnosticsBundle()
* LibraryContext._getLinkedBundleEntry()
- Bump AnalysisDriver.DATA_VERSION to 564 to invalidate stale caches.
Performance
-----------
- getLibraryDiagnosticsBundle elapsed time:
70.105 ms → 3.557 ms (−66.548 ms, −94.93%; ~19.71× faster) across
1,646 runs.
- Counters (after):
apiSignature=193, libDetails=8, libHash=17,916, libsDetails=7,
libsHash=1,444.
Correctness
-----------
- The hash is computed from exactly the manifest fields that validation
consults; equal hashes guarantee the same decision.
- When hashes differ, full validation runs as before.
- Export combinators, re-export flags, and opaque API handling are
unchanged and still enforced.
Impact
------
Expect faster cache hits when resolving/validating
diagnostics bundles and linked cycles, with no behavioral changes when
libraries actually differ.
Change-Id: Id3a631a680d21a994d4277a2d8f98040159c094d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/451820
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
This package provides a library that performs static analysis of Dart code. It is useful for tool integration and embedding.
End-users should use the dart analyze command-line tool to analyze their Dart code.
Integrators that want to add Dart support to their editor should use the Dart Analysis Server. The Analysis Server API Specification is available. If you are adding Dart support to an editor or IDE, please let us know by emailing our list.
Configuring the analyzer
Both dart analyze and Dart Analysis Server can be configured with an
analysis_options.yaml file (using an .analysis_options file is deprecated).
This YAML file can control which files and paths are analyzed,
which lints are applied, and more.
If you are embedding the analyzer library in your project, you are responsible for finding the analysis options file, parsing it, and configuring the analyzer.
The analysis options file should live at the root of your project (for example,
next to your pubspec.yaml). Different embedders of analyzer, such as
dart analyze or Dart Analysis Server, may choose to find the file in various
different ways. Consult their documentation to learn more.
Here is an example file that instructs the analyzer to ignore two files:
analyzer:
exclude:
- test/_data/p4/lib/lib1.dart
- test/_data/p5/p5.dart
- test/_data/bad*.dart
- test/_brokendata/**
Note that you can use globs, as defined by the glob package.
Here is an example file that enables two lint rules:
linter:
rules:
- camel_case_types
- empty_constructor_bodies
Check out all the available Dart lint rules.
You can combine the analyzer section and the linter section into a single
configuration. Here is an example:
analyzer:
exclude:
- test/_data/p4/lib/lib1.dart
linter:
rules:
- camel_case_types
For more information, see the docs for customizing static analysis.
Who uses this library?
Many tools embed this library, such as:
- dart format - a formatter for Dart code
- dart doc - a documentation generator for Dart code
- Dart Analysis Server - a stateful server that supports IDEs and editors
Support
Post issues and feature requests at https://github.com/dart-lang/sdk/issues. These will be triaged according to the analyzer triage priorities.
Questions and discussions are welcome at the Dart Analyzer Discussion Group.
Background
The APIs in this package were originally machine generated by a translator and were based on an earlier Java implementation. Several of the API's still look like their Java predecessors rather than clean Dart APIs.
In addition, there is currently no clean distinction between public and internal APIs. We plan to address this issue but doing so will, unfortunately, require a large number of breaking changes. We will try to minimize the pain this causes for our clients, but some pain is inevitable.
License
See the LICENSE file.