Faster predicate matching with integer tag ids.

app/bin/tools/search_benchmark.dart

@@ -5,6 +5,7 @@
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:_pub_shared/search/search_form.dart';
 import 'package:pub_dev/package/overrides.dart';
 import 'package:pub_dev/search/mem_index.dart';
 import 'package:pub_dev/search/models.dart';
@@ -24,6 +25,7 @@ Future<void> main(List<String> args) async {
 
   // NOTE: please add more queries to this list, especially if there is a performance bottleneck.
   final queries = [
+    'chart',
     'json',
     'camera',
     'android camera',
@@ -33,7 +35,10 @@ Future<void> main(List<String> args) async {
   final sw = Stopwatch()..start();
   var count = 0;
   for (var i = 0; i < 100; i++) {
-    index.search(ServiceSearchQuery.parse(query: queries[i % queries.length]));
+    index.search(ServiceSearchQuery.parse(
+      query: queries[i % queries.length],
+      tagsPredicate: TagsPredicate.regularSearch(),
+    ));
     count++;
   }
   sw.stop();

app/lib/search/mem_index.dart

@@ -28,6 +28,8 @@ class InMemoryPackageIndex {
   late final TokenIndex<String> _readmeIndex;
   late final TokenIndex<IndexedApiDocPage> _apiSymbolIndex;
   late final _scorePool = ScorePool(_packageNameIndex._packageNames);
+  final _tagIds = <String, int>{};
+  final _documentTagIds = <List<int>>[];
 
   /// Adjusted score takes the overall score and transforms
   /// it linearly into the [0.4-1.0] range.
@@ -58,6 +60,14 @@ class InMemoryPackageIndex {
       final doc = _documents[i];
       _documentsByName[doc.package] = doc;
 
+      // transform tags into numberical IDs
+      final tagIds = <int>[];
+      for (final tag in doc.tags) {
+        tagIds.add(_tagIds.putIfAbsent(tag, () => _tagIds.length));
+      }
+      tagIds.sort();
+      _documentTagIds.add(tagIds);
+
       final apiDocPages = doc.apiDocPages;
       if (apiDocPages != null) {
         for (final page in apiDocPages) {
@@ -144,8 +154,49 @@ class InMemoryPackageIndex {
     final combinedTagsPredicate =
         query.tagsPredicate.appendPredicate(query.parsedQuery.tagsPredicate);
     if (combinedTagsPredicate.isNotEmpty) {
-      packageScores.retainWhere(
-          (i, _) => combinedTagsPredicate.matches(_documents[i].tagsForLookup));
+      // The list of predicate tag entries, converted to tag IDs (or -1 if there is no indexed tag),
+      // sorted by their id.
+      final entriesToCheck = combinedTagsPredicate.entries
+          .map((e) => MapEntry(_tagIds[e.key] ?? -1, e.value))
+          .toList()
+        ..sort((a, b) => a.key.compareTo(b.key));
+
+      packageScores.retainWhere((docIndex, _) {
+        // keeping track of tag id iteration with the `nextTagIndex`
+        final tagIds = _documentTagIds[docIndex];
+        var nextTagIndex = 0;
+
+        for (final entry in entriesToCheck) {
+          if (entry.key == -1) {
+            // no tag id is present for this predicate
+            if (entry.value) {
+              // the predicate is required, no document will match it
+              return false;
+            } else {
+              // the predicate is prohibited, no document has it, always a match
+              continue;
+            }
+          }
+
+          // skipping the present tag ids until the currently matched predicate tag id
+          while (nextTagIndex < tagIds.length &&
+              tagIds[nextTagIndex] < entry.key) {
+            nextTagIndex++;
+          }
+
+          // checking presence
+          late bool present;
+          if (nextTagIndex == tagIds.length) {
+            present = false;
+          } else {
+            present = tagIds[nextTagIndex] == entry.key;
+          }
+
+          if (entry.value && !present) return false;
+          if (!entry.value && present) return false;
+        }
+        return true;
+      });
     }
 
     // filter on dependency

app/lib/search/search_service.dart

@@ -135,9 +135,6 @@ class PackageDocument {
 
   Map<String, dynamic> toJson() => _$PackageDocumentToJson(this);
 
-  @JsonKey(includeFromJson: false, includeToJson: false)
-  late final Set<String> tagsForLookup = Set.of(tags);
-
   late final packageNameLowerCased = package.toLowerCase();
 }
 

pkg/_pub_shared/lib/search/search_form.dart

@@ -131,6 +131,8 @@ class TagsPredicate {
   bool get isEmpty => _values.isEmpty;
   bool get isNotEmpty => _values.isNotEmpty;
 
+  Iterable<MapEntry<String, bool>> get entries => _values.entries;
+
   bool isRequiredTag(String tag) => _values[tag] == true;
   bool isProhibitedTag(String tag) => _values[tag] == false;
   bool hasTag(String tag) => _values.containsKey(tag);
@@ -187,19 +189,6 @@ class TagsPredicate {
     return p;
   }
 
-  /// Evaluate this predicate against the list of supplied [tags].
-  /// Returns true if the predicate matches the [tags], false otherwise.
-  bool matches(Iterable<String> tags) {
-    for (final entry in _values.entries) {
-      final tag = entry.key;
-      final required = entry.value;
-      final present = tags.contains(tag);
-      if (required && !present) return false;
-      if (!required && present) return false;
-    }
-    return true;
-  }
-
   /// Toggles [tag] between required and absent status.
   TagsPredicate toggleRequired(String tag) {
     final current = _values[tag];