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 <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -106,7 +106,7 @@ testFineAfterLibraryAnalyzerHook;
 // TODO(scheglov): Clean up the list of implicitly analyzed files.
 class AnalysisDriver {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 563;
+  static const int DATA_VERSION = 564;
 
   /// The number of exception contexts allowed to write. Once this field is
   /// zero, we stop writing any new exception contexts in this process.
@@ -1925,6 +1925,7 @@ class AnalysisDriver {
       var elementFactory = libraryContext.elementFactory;
       var failure = bundle.requirements.isSatisfied(
         elementFactory: elementFactory,
+        performance: performance,
       );
       scheduler.eventsController.add(
         events.CheckLibraryDiagnosticsRequirements(

pkg/analyzer/lib/src/dart/analysis/library_context.dart

@@ -240,7 +240,10 @@ class LibraryContext {
       }
 
       var failure = performance.run('checkRequirements', (performance) {
-        return entry.requirements.isSatisfied(elementFactory: elementFactory);
+        return entry.requirements.isSatisfied(
+          elementFactory: elementFactory,
+          performance: performance,
+        );
       });
 
       eventsController?.add(

pkg/analyzer/lib/src/fine/requirements.dart

@@ -16,6 +16,7 @@ import 'package:analyzer/src/fine/manifest_id.dart';
 import 'package:analyzer/src/fine/manifest_item.dart';
 import 'package:analyzer/src/fine/requirement_failure.dart';
 import 'package:analyzer/src/summary2/linked_element_factory.dart';
+import 'package:analyzer/src/util/performance/operation_performance.dart';
 import 'package:analyzer/src/utilities/extensions/string.dart';
 import 'package:collection/collection.dart';
 import 'package:meta/meta.dart';
@@ -490,6 +491,15 @@ class LibraryExportRequirements {
 }
 
 class LibraryRequirements {
+  /// Snapshot of [LibraryManifest.hashForRequirements] at recording.
+  ///
+  /// This serves as a fast-path check in [RequirementsManifest.isSatisfied].
+  /// If this hash matches the current hash on the corresponding
+  /// [LibraryManifest], it implies that the relevant portions of the library
+  /// have not changed, allowing the detailed, field-by-field requirement
+  /// validation for this library to be skipped.
+  String hashForRequirements;
+
   String? name;
   bool? isSynthetic;
   Uint8List? featureSet;
@@ -547,6 +557,7 @@ class LibraryRequirements {
   ManifestItemIdList? allDeclaredSetters;
 
   LibraryRequirements({
+    required this.hashForRequirements,
     required this.name,
     required this.isSynthetic,
     required this.featureSet,
@@ -581,16 +592,17 @@ class LibraryRequirements {
     required this.allDeclaredSetters,
   });
 
-  factory LibraryRequirements.empty() {
+  factory LibraryRequirements.fromManifest(LibraryManifest manifest) {
     return LibraryRequirements(
+      hashForRequirements: manifest.hashForRequirements,
       name: null,
       isSynthetic: null,
       featureSet: null,
       languageVersion: null,
       libraryMetadataId: null,
       exportedLibraryUris: null,
       exportMap: {},
-      exportMapId: ManifestItemId.generate(),
+      exportMapId: manifest.exportMapId,
       instances: {},
       interfaces: {},
       exportedExtensions: null,
@@ -620,6 +632,7 @@ class LibraryRequirements {
 
   factory LibraryRequirements.read(BinaryReader reader) {
     return LibraryRequirements(
+      hashForRequirements: reader.readStringUtf8(),
       name: reader.readOptionalStringUtf8(),
       isSynthetic: reader.readOptionalBool(),
       featureSet: reader.readOptionalUint8List(),
@@ -665,6 +678,7 @@ class LibraryRequirements {
   }
 
   void write(BinaryWriter writer) {
+    writer.writeStringUtf8(hashForRequirements);
     writer.writeOptionalStringUtf8(name);
     writer.writeOptionalBool(isSynthetic);
     writer.writeOptionalUint8List(featureSet);
@@ -867,11 +881,13 @@ class RequirementsManifest {
   /// are satisfied.
   RequirementFailure? isSatisfied({
     required LinkedElementFactory elementFactory,
+    required OperationPerformanceImpl performance,
   }) {
     if (opaqueApiUses.isNotEmpty) {
       return OpaqueApiUseFailure(uses: opaqueApiUses);
     }
 
+    var onlyHashForLibraries = true;
     for (var libraryEntry in libraries.entries) {
       var libraryUri = libraryEntry.key;
       var libraryRequirements = libraryEntry.value;
@@ -881,6 +897,15 @@ class RequirementsManifest {
         return LibraryMissing(uri: libraryUri);
       }
 
+      if (libraryRequirements.hashForRequirements ==
+          libraryManifest.hashForRequirements) {
+        performance.getDataInt('libHash').increment();
+        continue;
+      } else {
+        performance.getDataInt('libDetails').increment();
+        onlyHashForLibraries = false;
+      }
+
       if (libraryRequirements.name case var expected?) {
         var actual = libraryManifest.name;
         if (expected != actual) {
@@ -1525,6 +1550,12 @@ class RequirementsManifest {
       }
     }
 
+    if (onlyHashForLibraries) {
+      performance.getDataInt('libsHash').increment();
+    } else {
+      performance.getDataInt('libsDetails').increment();
+    }
+
     for (var exportRequirement in exportRequirements) {
       var failure = exportRequirement.isSatisfied(
         elementFactory: elementFactory,
@@ -2524,11 +2555,10 @@ class RequirementsManifest {
       return result;
     }
 
-    result = LibraryRequirements.empty();
-    result.exportMapId = element.manifest!.exportMapId;
-
+    result = LibraryRequirements.fromManifest(element.manifest!);
+    state._result = result;
     libraries[element.uri] = result;
-    return state._result = result;
+    return result;
   }
 
   String _qualifiedMethodName(