Use sync I/O. (#4000)

Author: davidmorgan

build/lib/src/state/filesystem.dart

@@ -6,36 +6,20 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
-import 'package:pool/pool.dart';
-
 /// The filesystem the build is running on.
 ///
 /// Methods behave as the `dart:io` methods with the same names, with some
 /// exceptions noted in the docs.
 abstract interface class Filesystem {
-  /// Whether the file exists.
-  Future<bool> exists(String path);
-
   /// Whether the file exists.
   bool existsSync(String path);
 
-  /// Reads a file as a string.
-  Future<String> readAsString(String path, {Encoding encoding = utf8});
-
   /// Reads a file as a string.
   String readAsStringSync(String path, {Encoding encoding = utf8});
 
-  /// Reads a file as bytes.
-  Future<Uint8List> readAsBytes(String path);
-
   /// Reads a file as bytes.
   Uint8List readAsBytesSync(String path);
 
-  /// Deletes a file.
-  ///
-  /// If the file does not exist, does nothing.
-  Future<void> delete(String path);
-
   /// Deletes a file.
   ///
   /// If the file does not exist, does nothing.
@@ -44,7 +28,7 @@ abstract interface class Filesystem {
   /// Deletes a directory recursively.
   ///
   /// If the directory does not exist, does nothing.
-  Future<void> deleteDirectory(String path);
+  void deleteDirectorySync(String path);
 
   /// Writes a file.
   ///
@@ -55,48 +39,20 @@ abstract interface class Filesystem {
     Encoding encoding = utf8,
   });
 
-  /// Writes a file.
-  ///
-  /// Creates enclosing directories as needed if they don't exist.
-  Future<void> writeAsString(
-    String path,
-    String contents, {
-    Encoding encoding = utf8,
-  });
-
   /// Writes a file.
   ///
   /// Creates enclosing directories as needed if they don't exist.
   void writeAsBytesSync(String path, List<int> contents);
-
-  /// Writes a file.
-  ///
-  /// Creates enclosing directories as needed if they don't exist.
-  Future<void> writeAsBytes(String path, List<int> contents);
 }
 
 /// The `dart:io` filesystem.
 class IoFilesystem implements Filesystem {
-  /// Pool for async file operations.
-  final _pool = Pool(32);
-
-  @override
-  Future<bool> exists(String path) => _pool.withResource(File(path).exists);
-
   @override
   bool existsSync(String path) => File(path).existsSync();
 
-  @override
-  Future<Uint8List> readAsBytes(String path) =>
-      _pool.withResource(File(path).readAsBytes);
-
   @override
   Uint8List readAsBytesSync(String path) => File(path).readAsBytesSync();
 
-  @override
-  Future<String> readAsString(String path, {Encoding encoding = utf8}) =>
-      _pool.withResource(() => File(path).readAsString(encoding: encoding));
-
   @override
   String readAsStringSync(String path, {Encoding encoding = utf8}) =>
       File(path).readAsStringSync(encoding: encoding);
@@ -108,19 +64,9 @@ class IoFilesystem implements Filesystem {
   }
 
   @override
-  Future<void> delete(String path) {
-    return _pool.withResource(() async {
-      final file = File(path);
-      if (await file.exists()) await file.delete();
-    });
-  }
-
-  @override
-  Future<void> deleteDirectory(String path) {
-    return _pool.withResource(() async {
-      final directory = Directory(path);
-      if (await directory.exists()) await directory.delete(recursive: true);
-    });
+  void deleteDirectorySync(String path) {
+    final directory = Directory(path);
+    if (directory.existsSync()) directory.deleteSync(recursive: true);
   }
 
   @override
@@ -134,15 +80,6 @@ class IoFilesystem implements Filesystem {
     file.writeAsBytesSync(contents);
   }
 
-  @override
-  Future<void> writeAsBytes(String path, List<int> contents) {
-    return _pool.withResource(() async {
-      final file = File(path);
-      await file.parent.create(recursive: true);
-      await file.writeAsBytes(contents);
-    });
-  }
-
   @override
   void writeAsStringSync(
     String path,
@@ -153,19 +90,6 @@ class IoFilesystem implements Filesystem {
     file.parent.createSync(recursive: true);
     file.writeAsStringSync(contents, encoding: encoding);
   }
-
-  @override
-  Future<void> writeAsString(
-    String path,
-    String contents, {
-    Encoding encoding = utf8,
-  }) {
-    return _pool.withResource(() async {
-      final file = File(path);
-      await file.parent.create(recursive: true);
-      await file.writeAsString(contents, encoding: encoding);
-    });
-  }
 }
 
 /// An in-memory [Filesystem].
@@ -175,53 +99,30 @@ class InMemoryFilesystem implements Filesystem {
   /// The paths to all files present on the filesystem.
   Iterable<String> get filePaths => _files.keys;
 
-  @override
-  Future<bool> exists(String path) => Future.value(_files.containsKey(path));
-
   @override
   bool existsSync(String path) => _files.containsKey(path);
 
-  @override
-  Future<Uint8List> readAsBytes(String path) => Future.value(_files[path]!);
-
   @override
   Uint8List readAsBytesSync(String path) => _files[path]!;
 
-  @override
-  Future<String> readAsString(String path, {Encoding encoding = utf8}) =>
-      Future.value(encoding.decode(_files[path]!));
-
   @override
   String readAsStringSync(String path, {Encoding encoding = utf8}) =>
       encoding.decode(_files[path]!);
 
-  @override
-  Future<void> delete(String path) {
-    _files.remove(path);
-    return Future.value();
-  }
-
   @override
   void deleteSync(String path) => _files.remove(path);
 
   @override
-  Future<void> deleteDirectory(String path) {
+  void deleteDirectorySync(String path) {
     final prefix = '$path/';
     _files.removeWhere((filePath, _) => filePath.startsWith(prefix));
-    return Future.value();
   }
 
   @override
   void writeAsBytesSync(String path, List<int> contents) {
     _files[path] = Uint8List.fromList(contents);
   }
 
-  @override
-  Future<void> writeAsBytes(String path, List<int> contents) {
-    _files[path] = Uint8List.fromList(contents);
-    return Future.value();
-  }
-
   @override
   void writeAsStringSync(
     String path,
@@ -230,14 +131,4 @@ class InMemoryFilesystem implements Filesystem {
   }) {
     _files[path] = Uint8List.fromList(encoding.encode(contents));
   }
-
-  @override
-  Future<void> writeAsString(
-    String path,
-    String contents, {
-    Encoding encoding = utf8,
-  }) {
-    _files[path] = Uint8List.fromList(encoding.encode(contents));
-    return Future.value();
-  }
 }

build/lib/src/state/filesystem_cache.dart

@@ -14,30 +14,25 @@ import 'lru_cache.dart';
 /// TODO(davidmorgan): benchmark, optimize the caching strategy.
 abstract interface class FilesystemCache {
   /// Clears all [ids] from all caches.
-  ///
-  /// Waits for any pending reads to complete first.
-  Future<void> invalidate(Iterable<AssetId> ids);
+  void invalidate(Iterable<AssetId> ids);
 
   /// Whether [id] exists.
   ///
   /// Returns a cached result if available, or caches and returns `ifAbsent()`.
-  Future<bool> exists(AssetId id, {required Future<bool> Function() ifAbsent});
+  bool exists(AssetId id, {required bool Function() ifAbsent});
 
   /// Reads [id] as bytes.
   ///
   /// Returns a cached result if available, or caches and returns `ifAbsent()`.
-  Future<Uint8List> readAsBytes(
-    AssetId id, {
-    required Future<Uint8List> Function() ifAbsent,
-  });
+  Uint8List readAsBytes(AssetId id, {required Uint8List Function() ifAbsent});
 
   /// Reads [id] as a `String`.
   ///
   /// Returns a cached result if available, or caches and returns `ifAbsent()`.
-  Future<String> readAsString(
+  String readAsString(
     AssetId id, {
     Encoding encoding = utf8,
-    required Future<Uint8List> Function() ifAbsent,
+    required Uint8List Function() ifAbsent,
   });
 }
 
@@ -49,23 +44,18 @@ class PassthroughFilesystemCache implements FilesystemCache {
   Future<void> invalidate(Iterable<AssetId> ids) async {}
 
   @override
-  Future<bool> exists(
-    AssetId id, {
-    required Future<bool> Function() ifAbsent,
-  }) => ifAbsent();
+  bool exists(AssetId id, {required bool Function() ifAbsent}) => ifAbsent();
 
   @override
-  Future<Uint8List> readAsBytes(
-    AssetId id, {
-    required Future<Uint8List> Function() ifAbsent,
-  }) => ifAbsent();
+  Uint8List readAsBytes(AssetId id, {required Uint8List Function() ifAbsent}) =>
+      ifAbsent();
 
   @override
-  Future<String> readAsString(
+  String readAsString(
     AssetId id, {
     Encoding encoding = utf8,
-    required Future<Uint8List> Function() ifAbsent,
-  }) async => encoding.decode(await ifAbsent());
+    required Uint8List Function() ifAbsent,
+  }) => encoding.decode(ifAbsent());
 }
 
 /// [FilesystemCache] that stores data in memory.
@@ -77,13 +67,10 @@ class InMemoryFilesystemCache implements FilesystemCache {
     (value) => value.lengthInBytes,
   );
 
-  /// Pending [readAsBytes] operations.
-  final _pendingBytesContentCache = <AssetId, Future<Uint8List>>{};
-
   /// Cached results of [exists].
   ///
   /// Don't bother using an LRU cache for this since it's just booleans.
-  final _canReadCache = <AssetId, Future<bool>>{};
+  final _existsCache = <AssetId, bool>{};
 
   /// Cached results of [readAsString].
   ///
@@ -96,64 +83,50 @@ class InMemoryFilesystemCache implements FilesystemCache {
     (value) => value.length,
   );
 
-  /// Pending `readAsString` operations.
-  final _pendingStringContentCache = <AssetId, Future<String>>{};
-
   @override
   Future<void> invalidate(Iterable<AssetId> ids) async {
-    // First finish all pending operations, as they will write to the cache.
-    for (var id in ids) {
-      await _canReadCache.remove(id);
-      await _pendingBytesContentCache.remove(id);
-      await _pendingStringContentCache.remove(id);
-    }
     for (var id in ids) {
+      _existsCache.remove(id);
       _bytesContentCache.remove(id);
       _stringContentCache.remove(id);
     }
   }
 
   @override
-  Future<bool> exists(
-    AssetId id, {
-    required Future<bool> Function() ifAbsent,
-  }) => _canReadCache.putIfAbsent(id, ifAbsent);
+  bool exists(AssetId id, {required bool Function() ifAbsent}) =>
+      _existsCache.putIfAbsent(id, ifAbsent);
 
   @override
-  Future<Uint8List> readAsBytes(
-    AssetId id, {
-    required Future<Uint8List> Function() ifAbsent,
-  }) {
-    var cached = _bytesContentCache[id];
-    if (cached != null) return Future.value(cached);
-
-    return _pendingBytesContentCache.putIfAbsent(id, () async {
-      final result = await ifAbsent();
-      _bytesContentCache[id] = result;
-      unawaited(_pendingBytesContentCache.remove(id));
-      return result;
-    });
+  Uint8List readAsBytes(AssetId id, {required Uint8List Function() ifAbsent}) {
+    final maybeResult = _bytesContentCache[id];
+    if (maybeResult != null) return maybeResult;
+
+    final result = ifAbsent();
+    _bytesContentCache[id] = result;
+    return result;
   }
 
   @override
-  Future<String> readAsString(
+  String readAsString(
     AssetId id, {
     Encoding encoding = utf8,
-    required Future<Uint8List> Function() ifAbsent,
-  }) async {
+    required Uint8List Function() ifAbsent,
+  }) {
     if (encoding != utf8) {
-      final bytes = await readAsBytes(id, ifAbsent: ifAbsent);
+      final bytes = readAsBytes(id, ifAbsent: ifAbsent);
       return encoding.decode(bytes);
     }
 
-    var cached = _stringContentCache[id];
-    if (cached != null) return cached;
+    final maybeResult = _stringContentCache[id];
+    if (maybeResult != null) return maybeResult;
 
-    return _pendingStringContentCache.putIfAbsent(id, () async {
-      final bytes = await ifAbsent();
-      final result = _stringContentCache[id] = utf8.decode(bytes);
-      unawaited(_pendingStringContentCache.remove(id));
-      return result;
-    });
+    var bytes = _bytesContentCache[id];
+    if (bytes == null) {
+      bytes = ifAbsent();
+      _bytesContentCache[id] = bytes;
+    }
+    final result = utf8.decode(bytes);
+    _stringContentCache[id] = result;
+    return result;
   }
 }