Use ScorePool for dartdoc and SDK search results. (#8321)

Author: isoos

app/lib/search/mem_index.dart

@@ -334,35 +334,36 @@ class InMemoryPackageIndex {
           List<List<MapEntry<String, double>>?>.filled(_documents.length, null);
       const maxApiPageCount = 2;
       if (!checkAborted()) {
-        final symbolPages = _apiSymbolIndex.searchWords(words, weight: 0.70);
-
-        for (var i = 0; i < symbolPages.length; i++) {
-          final value = symbolPages.getValue(i);
-          if (value < 0.01) continue;
-
-          final doc = symbolPages.keys[i];
-          if (!packages.contains(doc.package)) continue;
-
-          // skip if the previously found pages are better than the current one
-          final pages = topApiPages[doc.index] ??= <MapEntry<String, double>>[];
-          if (pages.length >= maxApiPageCount && pages.last.value > value) {
-            continue;
+        _apiSymbolIndex.withSearchWords(words, weight: 0.70, (symbolPages) {
+          for (var i = 0; i < symbolPages.length; i++) {
+            final value = symbolPages.getValue(i);
+            if (value < 0.01) continue;
+
+            final doc = symbolPages.keys[i];
+            if (!packages.contains(doc.package)) continue;
+
+            // skip if the previously found pages are better than the current one
+            final pages =
+                topApiPages[doc.index] ??= <MapEntry<String, double>>[];
+            if (pages.length >= maxApiPageCount && pages.last.value > value) {
+              continue;
+            }
+
+            // update the top api packages score
+            packageScores.setValueMaxOf(doc.index, value);
+
+            // add the page and re-sort the current results
+            pages.add(MapEntry(doc.page.relativePath, value));
+            if (pages.length > 1) {
+              pages.sort((a, b) => -a.value.compareTo(b.value));
+            }
+
+            // keep the results limited to the max count
+            if (pages.length > maxApiPageCount) {
+              pages.removeLast();
+            }
           }
-
-          // update the top api packages score
-          packageScores.setValueMaxOf(doc.index, value);
-
-          // add the page and re-sort the current results
-          pages.add(MapEntry(doc.page.relativePath, value));
-          if (pages.length > 1) {
-            pages.sort((a, b) => -a.value.compareTo(b.value));
-          }
-
-          // keep the results limited to the max count
-          if (pages.length > maxApiPageCount) {
-            pages.removeLast();
-          }
-        }
+        });
       }
 
       // filter results based on exact phrases

app/lib/search/sdk_mem_index.dart

@@ -137,7 +137,8 @@ class SdkMemIndex {
       final isQualifiedQuery = query.contains(library.split(':').last);
 
       final tokens = _tokensPerLibrary[library]!;
-      final plainResults = tokens.searchWords(words).top(3, minValue: 0.05);
+      final plainResults = tokens.withSearchWords(
+          words, (score) => score.top(3, minValue: 0.05));
       if (plainResults.isEmpty) continue;
 
       final libraryWeight = _libraryWeights[library] ?? 1.0;

app/lib/search/token_index.dart

@@ -34,6 +34,8 @@ class TokenIndex<K> {
 
   late final _length = _ids.length;
 
+  late final _scorePool = ScorePool(_ids);
+
   TokenIndex(
     List<K> ids,
     List<String?> values, {
@@ -96,22 +98,27 @@ class TokenIndex<K> {
     return tokenMatch;
   }
 
-  /// Search the index for [words], with a (term-match / document coverage percent)
-  /// scoring.
-  IndexedScore<K> searchWords(List<String> words, {double weight = 1.0}) {
+  /// Search the index for [words], providing the result [IndexedScore] values
+  /// in the [fn] callback, reusing the score buffers between calls.
+  R withSearchWords<R>(List<String> words, R Function(IndexedScore<K> score) fn,
+      {double weight = 1.0}) {
     IndexedScore<K>? score;
 
     weight = math.pow(weight, 1 / words.length).toDouble();
     for (final w in words) {
-      final s = IndexedScore(_ids);
+      final s = _scorePool._acquire(0.0);
       searchAndAccumulate(w, score: s, weight: weight);
       if (score == null) {
         score = s;
       } else {
         score.multiplyAllFrom(s);
+        _scorePool._release(s);
       }
     }
-    return score ?? IndexedScore(_ids);
+    score ??= _scorePool._acquire(0.0);
+    final r = fn(score);
+    _scorePool._release(score);
+    return r;
   }
 
   /// Searches the index with [word] and stores the results in [score], using
@@ -139,7 +146,7 @@ extension StringTokenIndexExt on TokenIndex<String> {
   /// scoring.
   @visibleForTesting
   Map<String, double> search(String text) {
-    return searchWords(splitForQuery(text)).toMap();
+    return withSearchWords(splitForQuery(text), (score) => score.toMap());
   }
 }
 
@@ -150,19 +157,28 @@ class ScorePool<K> {
 
   ScorePool(this._keys);
 
-  R withScore<R>({
-    required double value,
-    required R Function(IndexedScore<K> score) fn,
-  }) {
+  IndexedScore<K> _acquire(double value) {
     late IndexedScore<K> score;
     if (_pool.isNotEmpty) {
       score = _pool.removeLast();
       score._values.setAll(0, Iterable.generate(score.length, (_) => value));
     } else {
       score = IndexedScore<K>(_keys, value);
     }
-    final r = fn(score);
+    return score;
+  }
+
+  void _release(IndexedScore<K> score) {
     _pool.add(score);
+  }
+
+  R withScore<R>({
+    required double value,
+    required R Function(IndexedScore<K> score) fn,
+  }) {
+    final score = _acquire(value);
+    final r = fn(score);
+    _release(score);
     return r;
   }
 }