Started caching results from iana. (#53286)

dev/tools/localization/bin/gen_l10n.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:async';
 import 'dart:io';
 
 import 'package:args/args.dart' as argslib;
@@ -13,7 +12,7 @@ import '../gen_l10n.dart';
 import '../gen_l10n_types.dart';
 import '../localizations_utils.dart';
 
-Future<void> main(List<String> arguments) async {
+void main(List<String> arguments) {
   final argslib.ArgParser parser = argslib.ArgParser();
   parser.addFlag(
     'help',
@@ -80,7 +79,7 @@ Future<void> main(List<String> arguments) async {
     exit(0);
   }
 
-  await precacheLanguageAndRegionTags();
+  precacheLanguageAndRegionTags();
 
   final String arbPathString = results['arb-dir'] as String;
   final String outputFileString = results['output-localization-file'] as String;

dev/tools/localization/bin/gen_localizations.dart

@@ -40,7 +40,6 @@
 // dart dev/tools/localization/bin/gen_localizations.dart --overwrite
 // ```
 
-import 'dart:async';
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
@@ -480,7 +479,7 @@ String generateGetter(String key, String value, Map<String, dynamic> attributes,
   $type get $key => $value;''';
 }
 
-Future<void> main(List<String> rawArgs) async {
+void main(List<String> rawArgs) {
   checkCwdIsRepoRoot('gen_localizations');
   final GeneratorOptions options = parseArgs(rawArgs);
 
@@ -499,7 +498,7 @@ Future<void> main(List<String> rawArgs) async {
     exitWithError('$exception');
   }
 
-  await precacheLanguageAndRegionTags();
+  precacheLanguageAndRegionTags();
 
   // Maps of locales to resource key/value pairs for Material ARBs.
   final Map<LocaleInfo, Map<String, String>> materialLocaleToResources = <LocaleInfo, Map<String, String>>{};

dev/tools/localization/gen_subtag_registry.dart

@@ -0,0 +1,27 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+const String registry = 'https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry';
+
+/// A script to generate a Dart cache of https://www.iana.org.  This should be
+/// run occasionally.  It was created since iana.org was found to be flakey.
+///
+/// To execute: dart gen_subtag_registry.dart > language_subtag_registry.dart
+Future<void> main() async {
+  final HttpClient client = HttpClient();
+  final HttpClientRequest request = await client.getUrl(Uri.parse(registry));
+  final HttpClientResponse response = await request.close();
+  final String body = (await response.cast<List<int>>().transform<String>(utf8.decoder).toList()).join('');
+  print('''// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Cache of $registry.
+const String languageSubtagRegistry = \'\'\'$body\'\'\';''');
+  client.close(force: true);
+}

dev/tools/localization/localizations_utils.dart

@@ -2,13 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:args/args.dart' as argslib;
 import 'package:meta/meta.dart';
 
+import 'language_subtag_registry.dart';
+
 typedef HeaderGenerator = String Function(String regenerateInstructions);
 typedef ConstructorGenerator = String Function(LocaleInfo locale);
 
@@ -264,8 +265,6 @@ class GeneratorOptions {
   final bool cupertinoOnly;
 }
 
-const String registry = 'https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry';
-
 // See also //master/tools/gen_locale.dart in the engine repo.
 Map<String, List<String>> _parseSection(String section) {
   final Map<String, List<String>> result = <String, List<String>>{};
@@ -297,13 +296,9 @@ const String kParentheticalPrefix = ' (';
 /// Prepares the data for the [describeLocale] method below.
 ///
 /// The data is obtained from the official IANA registry.
-Future<void> precacheLanguageAndRegionTags() async {
-  final HttpClient client = HttpClient();
-  final HttpClientRequest request = await client.getUrl(Uri.parse(registry));
-  final HttpClientResponse response = await request.close();
-  final String body = (await response.cast<List<int>>().transform<String>(utf8.decoder).toList()).join('');
-  client.close(force: true);
-  final List<Map<String, List<String>>> sections = body.split('%%').skip(1).map<Map<String, List<String>>>(_parseSection).toList();
+void precacheLanguageAndRegionTags() {
+  final List<Map<String, List<String>>> sections =
+      languageSubtagRegistry.split('%%').skip(1).map<Map<String, List<String>>>(_parseSection).toList();
   for (final Map<String, List<String>> section in sections) {
     assert(section.containsKey('Type'), section.toString());
     final String type = section['Type'].single;

dev/tools/test/localization/gen_l10n_test.dart

@@ -47,11 +47,11 @@ void _standardFlutterDirectoryL10nSetup(FileSystem fs) {
 void main() {
   MemoryFileSystem fs;
 
-  setUp(() async {
+  setUp(() {
     fs = MemoryFileSystem(
       style: Platform.isWindows ? FileSystemStyle.windows : FileSystemStyle.posix
     );
-    await precacheLanguageAndRegionTags();
+    precacheLanguageAndRegionTags();
   });
 
   group('Setters', () {