[native_assets_builder] Set the last modified date of assets to the build output timestamp

.github/workflows/native.yaml

@@ -102,6 +102,9 @@ jobs:
       - run: dart pub get -C test_data/native_dynamic_linking/
         if: ${{ matrix.package == 'native_assets_builder' }}
 
+      - run: dart pub get -C test_data/asset_build_time/
+        if: ${{ matrix.package == 'native_assets_builder' }}
+
       - run: dart pub get -C example/build/native_dynamic_linking/
         if: ${{ matrix.package == 'native_assets_cli' }}
 

pkgs/native_assets_builder/lib/src/build_runner/build_runner.dart

@@ -625,6 +625,11 @@ ${result.stdout}
       for (final error in validateResult.errors) {
         logger.severe('- $error');
       }
+
+      if (success) {
+        await output.touchAssets();
+      }
+
       return (output, success);
     } on FormatException catch (e) {
       logger.severe('''
@@ -925,3 +930,21 @@ extension on DateTime {
 extension on Uri {
   Uri get parent => File(toFilePath()).parent.uri;
 }
+
+extension on api.BuildOutput {
+  /// Sets the last modified time of all assets to [timestamp].
+  ///
+  /// This ensures that caching mechanisms can use the last modified time of
+  /// assets to invalidate cached results that depend on assets.
+  Future<void> touchAssets() async {
+    await Future.wait(
+      [...assets, ...assetsForLinking.values]
+          .map((asset) => switch (asset) {
+                NativeCodeAssetImpl(:final file) => file!,
+                DataAssetImpl(:final file) => file,
+                _ => throw UnsupportedError('Unsupported asset type: $asset'),
+              })
+          .map((file) => File.fromUri(file).setLastModified(timestamp)),
+    );
+  }
+}

pkgs/native_assets_builder/test/build_runner/build_runner_touch_assets_test.dart

@@ -0,0 +1,62 @@
+// Copyright (c) 2024, 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 'dart:io';
+
+import 'package:native_assets_cli/native_assets_cli.dart' as api;
+import 'package:native_assets_cli/native_assets_cli_internal.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main() async {
+  test(
+    'set last modified date of assets to build output timestamp',
+    timeout: longTimeout,
+    () async {
+      await inTempDir((tempUri) async {
+        await copyTestProjects(targetUri: tempUri);
+        final packageUri = tempUri.resolve('asset_build_time/');
+
+        // First, run `pub get`, we need pub to resolve our dependencies.
+        await runPubGet(
+          workingDirectory: packageUri,
+          logger: logger,
+        );
+
+        final result = await build(
+          packageUri,
+          logger,
+          dartExecutable,
+          supportedAssetTypes: [api.NativeCodeAsset.type, api.DataAsset.type],
+        );
+
+        expect(result.assets, hasLength(2));
+
+        final buildTimeLibraryUri =
+            result.assets.whereType<NativeCodeAssetImpl>().single.file!;
+        final buildDirectoryUri = buildTimeLibraryUri.resolve('./');
+
+        final buildOutputUri = buildDirectoryUri.resolve('build_output.json');
+        final buildOutput = HookOutputImpl.fromJsonString(
+            await File.fromUri(buildOutputUri).readAsString());
+
+        expect(
+          File.fromUri(buildTimeLibraryUri).lastModifiedSync(),
+          buildOutput.timestamp,
+        );
+
+        final buildTimeDataAssetUri =
+            result.assets.whereType<DataAssetImpl>().single.file;
+        expect(
+          File.fromUri(buildTimeDataAssetUri).lastModifiedSync(),
+          buildOutput.timestamp,
+        );
+      });
+    },
+  );
+}

pkgs/native_assets_builder/test_data/asset_build_time/build_time

@@ -0,0 +1 @@
+2024-01-01T00:00:00.000Z

pkgs/native_assets_builder/test_data/asset_build_time/ffigen.yaml

@@ -0,0 +1,20 @@
+# Run with `flutter pub run ffigen --config ffigen.yaml`.
+name: AssetBuildTimeBindings
+description: |
+  Bindings for `src/asset_build_time.h`.
+
+  Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
+output: 'lib/src/asset_build_time_bindings_generated.dart'
+headers:
+  entry-points:
+    - 'src/asset_build_time.h'
+  include-directives:
+    - 'src/asset_build_time.h'
+preamble: |
+  // Copyright (c) 2024, 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.
+comments:
+  style: any
+  length: full
+ffi-native:

pkgs/native_assets_builder/test_data/asset_build_time/hook/build.dart

@@ -0,0 +1,63 @@
+// Copyright (c) 2024, 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 'dart:io';
+
+import 'package:logging/logging.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+import 'package:native_toolchain_c/native_toolchain_c.dart';
+
+void main(List<String> arguments) async {
+  await build(arguments, (config, output) async {
+    final buildTimeFileUri = config.packageRoot.resolve('build_time');
+    final buildTime =
+        DateTime.parse(File.fromUri(buildTimeFileUri).readAsStringSync());
+    output.addDependency(buildTimeFileUri);
+
+    final name = config.packageName;
+
+    final cbuilder = CBuilder.library(
+      name: config.packageName,
+      assetName: 'src/${name}_bindings_generated.dart',
+      sources: [
+        'src/$name.c',
+      ],
+      defines: {
+        'BUILD_TIME': '"${buildTime.toIso8601String()}"',
+      },
+    );
+    await cbuilder.run(
+      config: config,
+      output: output,
+      logger: Logger('')
+        ..level = Level.ALL
+        ..onRecord.listen((record) {
+          print('${record.level.name}: ${record.time}: ${record.message}');
+        }),
+    );
+
+    if (config.supportedAssetTypes.contains(DataAsset.type)) {
+      final buildTimeDataAssetUri =
+          config.outputDirectory.resolve('build_time');
+      output.addAsset(
+        DataAsset(
+          package: config.packageName,
+          name: 'build_time',
+          file: buildTimeDataAssetUri,
+        ),
+      );
+
+      if (!config.dryRun) {
+        File.fromUri(buildTimeDataAssetUri)
+            .writeAsStringSync(buildTime.toIso8601String());
+      }
+    }
+
+    if (!config.dryRun) {
+      for (final asset in output.assets) {
+        File.fromUri(asset.file!).setLastModifiedSync(buildTime);
+      }
+    }
+  });
+}

pkgs/native_assets_builder/test_data/asset_build_time/lib/asset_build_time.dart

@@ -0,0 +1,5 @@
+// Copyright (c) 2024, 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.
+
+export 'src/asset_build_time.dart';

pkgs/native_assets_builder/test_data/asset_build_time/lib/src/asset_build_time.dart

@@ -0,0 +1,10 @@
+// Copyright (c) 2024, 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:ffi/ffi.dart';
+
+import 'asset_build_time_bindings_generated.dart' as bindings;
+
+DateTime get buildTime =>
+    DateTime.parse(bindings.buildTime.cast<Utf8>().toDartString());

pkgs/native_assets_builder/test_data/asset_build_time/lib/src/asset_build_time_bindings_generated.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2024, 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.
+
+// AUTO GENERATED FILE, DO NOT EDIT.
+//
+// Generated by `package:ffigen`.
+// ignore_for_file: type=lint
+import 'dart:ffi' as ffi;
+
+@ffi.Native<ffi.Pointer<ffi.Char>>()
+external ffi.Pointer<ffi.Char> buildTime;

pkgs/native_assets_builder/test_data/asset_build_time/pubspec.yaml

@@ -0,0 +1,25 @@
+name: asset_build_time
+description:
+  Embeds a build time into a library and a data asset and sets it as the assets
+  last modified time.
+version: 1.0.0
+
+publish_to: none
+
+environment:
+  sdk: '>=3.3.0 <4.0.0'
+
+dependencies:
+  ffi: ^2.1.3
+  logging: ^1.1.1
+  # native_assets_cli: ^0.7.3
+  native_assets_cli:
+    path: ../../../native_assets_cli/
+  # native_toolchain_c: ^0.5.3
+  native_toolchain_c:
+    path: ../../../native_toolchain_c/
+
+dev_dependencies:
+  ffigen: ^13.0.0
+  lints: ^3.0.0
+  test: ^1.23.1

pkgs/native_assets_builder/test_data/asset_build_time/src/asset_build_time.c

@@ -0,0 +1,7 @@
+// Copyright (c) 2024, 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.
+
+#include "asset_build_time.h"
+
+char *buildTime = BUILD_TIME;

pkgs/native_assets_builder/test_data/asset_build_time/src/asset_build_time.h

@@ -0,0 +1,11 @@
+// Copyright (c) 2024, 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.
+
+#if _WIN32
+#define MYLIB_EXPORT __declspec(dllexport)
+#else
+#define MYLIB_EXPORT
+#endif
+
+MYLIB_EXPORT char* buildTime;

pkgs/native_assets_builder/test_data/asset_build_time/test/asset_build_time_test.dart

@@ -0,0 +1,14 @@
+// Copyright (c) 2024, 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 'dart:io';
+
+import 'package:asset_build_time/asset_build_time.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('library build time test', () {
+    expect(buildTime, DateTime.parse(File('build_time').readAsStringSync()));
+  });
+}

pkgs/native_assets_builder/test_data/manifest.yaml

@@ -134,3 +134,13 @@
 - native_dynamic_linking/ffigen.yaml
 - native_dynamic_linking/pubspec.yaml
 - native_dynamic_linking/README.md
+- asset_build_time/build_time
+- asset_build_time/ffigen.yaml
+- asset_build_time/hook/build.dart
+- asset_build_time/lib/asset_build_time.dart
+- asset_build_time/lib/src/asset_build_time_bindings_generated.dart
+- asset_build_time/lib/src/asset_build_time.dart
+- asset_build_time/pubspec.yaml
+- asset_build_time/src/asset_build_time.c
+- asset_build_time/src/asset_build_time.h
+- asset_build_time/test/asset_build_time_test.dart