Fine. Short-circuit requirement checks with hashForRequirements
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>
https://dart.googlesource.com/sdk/+/9052ec70ed2f27ddbf1f3f8ddba444639e0aab4c
Monorepo is:
With depot_tools installed and on your path, create a directory for your monorepo checkout and run these commands to create a gclient solution in that directory:
mkdir monorepo cd monorepo gclient config --unmanaged https://dart.googlesource.com/monorepo gclient sync -D
This gives you a checkout in the monorepo directory that contains:
monorepo/ DEPS - the DEPS used for this gclient checkout commits.json - the pinned commits for Dart, flutter/engine, and flutter/flutter tools/ - scripts used to create monorepo DEPS engine/src/ - the flutter/buildroot repo flutter/ - the flutter/engine repo out/ - the build directory, where Flutter engine builds are created third_party/ - Flutter dependencies checked out by DEPS dart/ - the Dart SDK checkout. third_party - Dart dependencies, also used by Flutter flutter/ - the flutter/flutter repo
Flutter's instructions for building the engine are at Compiling the engine
They can be followed closely, with a few changes:
goma_ctl ensure_start is sufficient.Example build commands that work on linux:
MONOREPO_PATH=$PWD if [[ ! $PATH =~ (^|:)$MONOREPO_PATH/flutter/bin(:|$) ]]; then PATH=$MONOREPO_PATH/flutter/bin:$PATH fi export GOMA_DIR=$(dirname $(command -v gclient))/.cipd_bin goma_ctl ensure_start pushd engine/src flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk autoninja -C out/host_debug_unopt popd
The Flutter commands used to build and run apps will use the locally built Flutter engine and Dart SDK, instead of the one downloaded by the Flutter tool, if the --local-engine option is provided.
For example, to build and run the Flutter spinning square sample on the web platform,
MONOREPO_PATH=$PWD cd flutter/examples/layers flutter --local-engine=host_debug_unopt \ -d chrome run widgets/spinning_square.dart cd $MONOREPO_PATH
To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command
flutter create --platforms=windows,macos,linux
on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter
Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:
MONOREPO_PATH=$PWD cd flutter/packages/flutter flutter test --local-engine=host_debug_unopt cd $MONOREPO_PATH
Please file an issue or email the dart-engprod team with any problems with or questions about using monorepo.
We will update this documentation to address them.
flutter commands may download the engine and Dart SDK files for the configured channel, even though they will be using the local engine and its SDK.gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.