Modify FileResolver / bytestore to keep track of invalidated cache elements.

Change-Id: I60cb1f5f04eb9a1ee34c50157d5ed2da92d408ec
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/167861
Commit-Queue: Keerti Parthasarathy <keertip@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/dart/micro/cider_byte_store.dart

@@ -5,6 +5,13 @@
 import 'package:analyzer/src/dart/analysis/cache.dart';
 import 'package:collection/collection.dart';
 
+class CacheData {
+  final int id;
+  final List<int> bytes;
+
+  CacheData(this.id, this.bytes);
+}
+
 /// Store of bytes associated with string keys and a hash.
 ///
 /// Each key must be not longer than 100 characters and consist of only `[a-z]`,
@@ -18,39 +25,52 @@ abstract class CiderByteStore {
   /// [signature].
   ///
   /// Return `null` if the association does not exist.
-  List<int> get(String key, List<int> signature);
+  CacheData get(String key, List<int> signature);
 
-  /// Associate the given [bytes] with the [key] and [digest].
-  void put(String key, List<int> signature, List<int> bytes);
+  /// Associate the given [bytes] with the [key] and [signature]. Return the
+  /// [CacheData].
+  CacheData putGet(String key, List<int> signature, List<int> bytes);
+
+  ///  Used to decrement reference count for the given ids, if implemented.
+  void release(Iterable<int> ids);
 }
 
 class CiderCachedByteStore implements CiderByteStore {
   final Cache<String, CiderCacheEntry> _cache;
+  int idCounter = 0;
 
   CiderCachedByteStore(int maxCacheSize)
-      : _cache =
-            Cache<String, CiderCacheEntry>(maxCacheSize, (v) => v.bytes.length);
+      : _cache = Cache<String, CiderCacheEntry>(
+            maxCacheSize, (v) => v.data.bytes.length);
 
   @override
-  List<int> get(String key, List<int> signature) {
+  CacheData get(String key, List<int> signature) {
     var entry = _cache.get(key, () => null);
 
     if (entry != null &&
         const ListEquality<int>().equals(entry.signature, signature)) {
-      return entry.bytes;
+      return entry.data;
     }
     return null;
   }
 
   @override
-  void put(String key, List<int> signature, List<int> bytes) {
-    _cache.put(key, CiderCacheEntry(signature, bytes));
+  CacheData putGet(String key, List<int> signature, List<int> bytes) {
+    idCounter++;
+    var entry = CiderCacheEntry(signature, CacheData(idCounter, bytes));
+    _cache.put(key, entry);
+    return entry.data;
+  }
+
+  @override
+  void release(Iterable<int> ids) {
+    // do nothing
   }
 }
 
 class CiderCacheEntry {
+  final CacheData data;
   final List<int> signature;
-  final List<int> bytes;
 
-  CiderCacheEntry(this.signature, this.bytes);
+  CiderCacheEntry(this.signature, this.data);
 }

pkg/analyzer/lib/src/dart/micro/library_graph.dart

@@ -90,6 +90,9 @@ class FileState {
   UnlinkedUnit2 unlinked2;
   LibraryCycle _libraryCycle;
 
+  /// id of the cache entry.
+  int id;
+
   FileState._(
     this._fsState,
     this.path,
@@ -219,7 +222,8 @@ class FileState {
     // Prepare bytes of the unlinked bundle - existing or new.
     List<int> bytes;
     {
-      bytes = _fsState._byteStore.get(unlinkedKey, _digest);
+      var cacheData = _fsState._byteStore.get(unlinkedKey, _digest);
+      bytes = cacheData?.bytes;
 
       if (bytes == null || bytes.isEmpty) {
         var content = performance.run('content', (_) {
@@ -236,7 +240,8 @@ class FileState {
           var unlinkedBuilder = serializeAstCiderUnlinked(_digest, unit);
           bytes = unlinkedBuilder.toBuffer();
           performance.getDataInt('length').add(bytes.length);
-          _fsState._byteStore.put(unlinkedKey, _digest, bytes);
+          cacheData = _fsState._byteStore.putGet(unlinkedKey, _digest, bytes);
+          bytes = cacheData.bytes;
         });
 
         performance.run('prefetch', (_) {
@@ -244,6 +249,7 @@ class FileState {
           _prefetchDirectReferences(unlinked2);
         });
       }
+      id = cacheData.id;
     }
 
     // Read the unlinked bundle.
@@ -645,6 +651,9 @@ class LibraryCycle {
   /// The hash of all the paths of the files in this cycle.
   String cyclePathsHash;
 
+  /// id of the cache entry.
+  int id;
+
   LibraryCycle();
 
   String get signatureStr {

pkg/analyzer/lib/src/dart/micro/resolve_file.dart

@@ -83,6 +83,11 @@ class FileResolver {
 
   _LibraryContext libraryContext;
 
+  /// List of ids for cache elements that are invalidated. Track elements that
+  /// are invalidated during [changeFile]. Used in [releaseAndClearRemovedIds] to
+  /// release the cache items and is then cleared.
+  final Set<int> removedCacheIds = {};
+
   FileResolver(
     PerformanceLog logger,
     ResourceProvider resourceProvider,
@@ -132,7 +137,8 @@ class FileResolver {
   /// Update the resolver to reflect the fact that the file with the given
   /// [path] was changed. We need to make sure that when this file, of any file
   /// that directly or indirectly referenced it, is resolved, we used the new
-  /// state of the file.
+  /// state of the file. Updates [removedCacheIds] with the ids of the invalidated
+  /// items, used in [releaseAndClearRemovedIds] to release the cache items.
   void changeFile(String path) {
     if (fsState == null) {
       return;
@@ -149,12 +155,13 @@ class FileResolver {
         path: removedFile.path,
         uri: removedFile.uri,
       );
+      removedCacheIds.add(removedFile.id);
     }
 
     // Remove libraries represented by removed files.
     // If we need these libraries later, we will relink and reattach them.
     if (libraryContext != null) {
-      libraryContext.remove(removedFiles);
+      libraryContext.remove(removedFiles, removedCacheIds);
     }
   }
 
@@ -184,7 +191,7 @@ class FileResolver {
         var errorsSignature = errorsSignatureBuilder.toByteList();
 
         var errorsKey = file.path + '.errors';
-        var bytes = byteStore.get(errorsKey, errorsSignature);
+        var bytes = byteStore.get(errorsKey, errorsSignature)?.bytes;
         List<AnalysisError> errors;
         if (bytes != null) {
           var data = CiderUnitErrors.fromBuffer(bytes);
@@ -204,7 +211,7 @@ class FileResolver {
             signature: errorsSignature,
             errors: errors.map(ErrorEncoding.encode).toList(),
           ).toBuffer();
-          byteStore.put(errorsKey, errorsSignature, bytes);
+          bytes = byteStore.putGet(errorsKey, errorsSignature, bytes).bytes;
         }
 
         return ErrorsResultImpl(
@@ -314,6 +321,12 @@ class FileResolver {
     _resetContextObjects();
   }
 
+  /// Update the cache with list of invalidated ids and clears [removedCacheIds].
+  void releaseAndClearRemovedIds() {
+    byteStore.release(removedCacheIds);
+    removedCacheIds.clear();
+  }
+
   /// The [completionLine] and [completionColumn] are zero based.
   ResolvedUnitResult resolve({
     int completionLine,
@@ -680,7 +693,8 @@ class _LibraryContext {
       cycle.directDependencies.forEach(loadBundle);
 
       var key = cycle.cyclePathsHash;
-      var bytes = byteStore.get(key, cycle.signature);
+      var data = byteStore.get(key, cycle.signature);
+      var bytes = data?.bytes;
 
       if (bytes == null) {
         librariesLinkedTimer.start();
@@ -732,7 +746,8 @@ class _LibraryContext {
 
         bytes = serializeBundle(cycle.signature, linkResult).toBuffer();
 
-        byteStore.put(key, cycle.signature, bytes);
+        data = byteStore.putGet(key, cycle.signature, bytes);
+        bytes = data.bytes;
         performance.getDataInt('bytesPut').add(bytes.length);
 
         librariesLinkedTimer.stop();
@@ -740,6 +755,7 @@ class _LibraryContext {
         performance.getDataInt('bytesGet').add(bytes.length);
         performance.getDataInt('libraryLoadCount').add(cycle.libraries.length);
       }
+      cycle.id = data.id;
 
       var cBundle = CiderLinkedLibraryCycle.fromBuffer(bytes);
       inputBundles.add(cBundle.bundle);
@@ -775,14 +791,18 @@ class _LibraryContext {
 
   /// Remove libraries represented by the [removed] files.
   /// If we need these libraries later, we will relink and reattach them.
-  void remove(List<FileState> removed) {
+  void remove(List<FileState> removed, Set<int> removedIds) {
     elementFactory.removeLibraries(
       removed.map((e) => e.uriStr).toSet(),
     );
 
     var removedSet = removed.toSet();
     loadedBundles.removeWhere((cycle) {
-      return cycle.libraries.any(removedSet.contains);
+      if (cycle.libraries.any(removedSet.contains)) {
+        removedIds.add(cycle.id);
+        return true;
+      }
+      return false;
     });
   }