| // Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import 'package:analyzer/dart/ast/ast.dart'; |
| import 'package:analyzer/dart/ast/visitor.dart'; |
| import 'package:analyzer/dart/element/element.dart'; |
| import 'package:analyzer/dart/element/type.dart'; |
| |
| import '../analyzer.dart'; |
| import '../util/dart_type_utilities.dart'; |
| |
| const _desc = r'Avoid slow async `dart:io` methods.'; |
| |
| const _details = r''' |
| |
| **AVOID** using the following asynchronous file I/O methods because they are |
| much slower than their synchronous counterparts. |
| |
| * `Directory.exists` |
| * `Directory.stat` |
| * `File.lastModified` |
| * `File.exists` |
| * `File.stat` |
| * `FileSystemEntity.isDirectory` |
| * `FileSystemEntity.isFile` |
| * `FileSystemEntity.isLink` |
| * `FileSystemEntity.type` |
| |
| **BAD:** |
| ```dart |
| import 'dart:io'; |
| |
| Future<Null> someFunction() async { |
| var file = File('/path/to/my/file'); |
| var now = DateTime.now(); |
| if ((await file.lastModified()).isBefore(now)) print('before'); // LINT |
| } |
| ``` |
| |
| **GOOD:** |
| ```dart |
| import 'dart:io'; |
| |
| Future<Null> someFunction() async { |
| var file = File('/path/to/my/file'); |
| var now = DateTime.now(); |
| if (file.lastModifiedSync().isBefore(now)) print('before'); // OK |
| } |
| ``` |
| |
| '''; |
| |
| const List<String> _fileMethodNames = <String>[ |
| 'lastModified', |
| 'exists', |
| 'stat', |
| ]; |
| |
| const List<String> _dirMethodNames = <String>[ |
| 'exists', |
| 'stat', |
| ]; |
| |
| const List<String> _fileSystemEntityMethodNames = <String>[ |
| 'isDirectory', |
| 'isFile', |
| 'isLink', |
| 'type', |
| ]; |
| |
| class AvoidSlowAsyncIo extends LintRule implements NodeLintRule { |
| AvoidSlowAsyncIo() |
| : super( |
| name: 'avoid_slow_async_io', |
| description: _desc, |
| details: _details, |
| group: Group.errors); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| var visitor = _Visitor(this); |
| registry.addMethodInvocation(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitMethodInvocation(MethodInvocation node) { |
| if (node.argumentList.arguments.isEmpty) { |
| var type = node.target?.staticType; |
| _checkFileMethods(node, type); |
| _checkDirectoryMethods(node, type); |
| return; |
| } else { |
| _checkFileSystemEntityMethods(node); |
| return; |
| } |
| } |
| |
| void _checkFileMethods(MethodInvocation node, DartType? type) { |
| if (DartTypeUtilities.extendsClass(type, 'File', 'dart.io')) { |
| if (_fileMethodNames.contains(node.methodName.name)) { |
| rule.reportLint(node); |
| } |
| } |
| } |
| |
| void _checkDirectoryMethods(MethodInvocation node, DartType? type) { |
| if (DartTypeUtilities.extendsClass(type, 'Directory', 'dart.io')) { |
| if (_dirMethodNames.contains(node.methodName.name)) { |
| rule.reportLint(node); |
| } |
| } |
| } |
| |
| void _checkFileSystemEntityMethods(MethodInvocation node) { |
| var target = node.target; |
| if (target is Identifier) { |
| var elem = target.staticElement; |
| if (elem is ClassElement && elem.name == 'FileSystemEntity') { |
| if (_fileSystemEntityMethodNames.contains(node.methodName.name)) { |
| rule.reportLint(node); |
| } |
| } |
| } |
| } |
| } |