[jnigen] Initial code generator support (#19)

Author: mahesh-hegde

.github/workflows/test-package.yml

@@ -17,8 +17,14 @@ env:
   PUB_ENVIRONMENT: bot.github
 
 jobs:
-  # Check code formatting and static analysis on a single OS (linux)
-  # against Dart stable.
+  check_java_format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2 # v2 minimum required
+      - uses: axel-op/googlejavaformat-action@v3
+        with:
+          args: "--set-exit-if-changed"
+
   analyze_jni_gen:
     runs-on: ubuntu-latest
     defaults:
@@ -60,6 +66,11 @@ jobs:
       - uses: dart-lang/[email protected]
         with:
           sdk: stable
+      - uses: actions/setup-java@v2
+        with:
+          distribution: 'zulu'
+          java-version: '11'
+          cache: maven
       - name: Install dependencies
         run: dart pub get
       - name: Run VM tests
@@ -80,6 +91,20 @@ jobs:
   ## i.e do not rerun analyze and format steps, and do not require flutter.
   ## IssueRef: https://github.com/dart-lang/jni_gen/issues/15
 
+  test_summarizer:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: pkg/jni_gen/java
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v2
+        with:
+          distribution: 'zulu'
+          java-version: '11'
+      - name: run tests using maven surefire
+        run: mvn surefire:test
+
   test_jni:
     runs-on: ubuntu-latest
     defaults:
@@ -139,12 +164,9 @@ jobs:
       - run: |
           sudo apt-get update -y
           sudo apt-get install -y ninja-build libgtk-3-dev
-      - run: dart pub get
-        working-directory: pkg/jni
-      - run: dart run bin/setup.dart
-        working-directory: pkg/jni
       - run: flutter config --enable-linux-desktop
       - run: flutter pub get
+      - run: dart run jni:setup
       - run: flutter test
       - run: flutter build linux
 

pkgs/jni/android/build.gradle

@@ -31,12 +31,9 @@ android {
 
     // Bumping the plugin ndkVersion requires all clients of this plugin to bump
     // the version in their app and to download a newer version of the NDK.
-
-    // Note(MaheshH): Seems 22 is lowest one can get through SDKManager now?
-    //
-    // It's more of a logistic issue, I can't download NDK 21, so keeping it
-    // 22. You might get a warning to bump some versions.
-    ndkVersion "22.1.7171670"
+    // Note(MaheshH) - Flutter seems to download minimum NDK of flutter when
+    // below line is commented out.
+    // How about leaving it?
     // ndkVersion "21.1.6352462"
 
     // Invoke the shared CMake build with the Android Gradle Plugin.

pkgs/jni/android/src/main/java/dev/dart/jni/JniPlugin.java

@@ -1,32 +1,29 @@
 package dev.dart.jni;
 
+import android.app.Activity;
+import android.content.Context;
 import androidx.annotation.Keep;
 import androidx.annotation.NonNull;
-import android.util.Log;
-import android.app.Activity;
-import io.flutter.plugin.common.PluginRegistry.Registrar;
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.embedding.engine.plugins.activity.ActivityAware;
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
-
-import android.content.Context;
+import io.flutter.plugin.common.PluginRegistry.Registrar;
 
 @Keep
 public class JniPlugin implements FlutterPlugin, ActivityAware {
-  
+
   @Override
-  public void
-  onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
-	  setup(binding.getApplicationContext());
+  public void onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
+    setup(binding.getApplicationContext());
   }
 
   public static void registerWith(Registrar registrar) {
     JniPlugin plugin = new JniPlugin();
-	plugin.setup(registrar.activeContext());
+    plugin.setup(registrar.activeContext());
   }
 
   private void setup(Context context) {
-	initializeJni(context, getClass().getClassLoader());
+    initializeJni(context, getClass().getClassLoader());
   }
 
   @Override
@@ -35,27 +32,27 @@ public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {}
   // Activity handling methods
   @Override
   public void onAttachedToActivity(@NonNull ActivityPluginBinding binding) {
-	Activity activity = binding.getActivity();
-	setJniActivity(activity, activity.getApplicationContext());
+    Activity activity = binding.getActivity();
+    setJniActivity(activity, activity.getApplicationContext());
   }
 
   @Override
   public void onDetachedFromActivityForConfigChanges() {}
 
   @Override
   public void onReattachedToActivityForConfigChanges(@NonNull ActivityPluginBinding binding) {
-	Activity activity = binding.getActivity();
-	setJniActivity(activity, activity.getApplicationContext());
+    Activity activity = binding.getActivity();
+    setJniActivity(activity, activity.getApplicationContext());
   }
 
   @Override
   public void onDetachedFromActivity() {}
 
   native void initializeJni(Context context, ClassLoader classLoader);
+
   native void setJniActivity(Activity activity, Context context);
 
   static {
-	System.loadLibrary("dartjni");
+    System.loadLibrary("dartjni");
   }
 }
-

pkgs/jni/bin/setup.dart

@@ -5,10 +5,27 @@ import 'package:package_config/package_config.dart';
 
 const _buildDir = "build-dir";
 const _srcDir = "source-dir";
+const _packageName = 'package-name';
 const _verbose = "verbose";
 const _cmakeArgs = "cmake-args";
 const _clean = "clean";
 
+const _cmakeTemporaryFiles = [
+  'CMakeCache.txt',
+  'CMakeFiles/',
+  'cmake_install.cmake',
+  'Makefile'
+];
+
+void deleteCMakeTemps(Uri buildDir) async {
+  for (var filename in _cmakeTemporaryFiles) {
+    if (options.verbose) {
+      stderr.writeln('remove $filename');
+    }
+    await File(buildDir.resolve(filename).toFilePath()).delete(recursive: true);
+  }
+}
+
 // Sets up input output channels and maintains state.
 class CommandRunner {
   CommandRunner({this.printCmds = false});
@@ -25,7 +42,7 @@ class CommandRunner {
     }
     final process = await Process.start(exec, args,
         workingDirectory: workingDir,
-        runInShell: Platform.isWindows,
+        runInShell: true,
         mode: ProcessStartMode.inheritStdio);
     final exitCode = await process.exitCode;
     if (exitCode != 0) {
@@ -39,11 +56,14 @@ class Options {
   Options(ArgResults arg)
       : buildDir = arg[_buildDir],
         srcDir = arg[_srcDir],
+        packageName = arg[_packageName] ?? 'jni',
         cmakeArgs = arg[_cmakeArgs],
         verbose = arg[_verbose] ?? false,
         clean = arg[_clean] ?? false;
 
-  String? buildDir, srcDir, cmakeArgs;
+  String? buildDir, srcDir;
+  String packageName;
+  List<String> cmakeArgs;
   bool verbose, clean;
 }
 
@@ -63,7 +83,7 @@ Future<String?> findSources() async {
   }
   final packages = packageConfig.packages;
   for (var package in packages) {
-    if (package.name == 'jni') {
+    if (package.name == options.packageName) {
       return package.root.resolve("src/").toFilePath();
     }
   }
@@ -76,14 +96,18 @@ void main(List<String> arguments) async {
         abbr: 'B', help: 'Directory to place built artifacts')
     ..addOption(_srcDir,
         abbr: 'S', help: 'alternative path to package:jni sources')
+    ..addOption(_packageName,
+        abbr: 'p',
+        help: 'package for which native'
+            'library should be built',
+        defaultsTo: 'jni')
     ..addFlag(_verbose, abbr: 'v', help: 'Enable verbose output')
     ..addFlag(_clean,
         negatable: false,
         abbr: 'C',
         help: 'Clear built artifacts instead of running a build')
-    ..addOption(_cmakeArgs,
-        abbr: 'm',
-        help: 'additional space separated arguments to pass to CMake');
+    ..addMultiOption(_cmakeArgs,
+        abbr: 'm', help: 'additional argument to pass to CMake');
   final cli = parser.parse(arguments);
   options = Options(cli);
   final rest = cli.rest;
@@ -114,7 +138,7 @@ void main(List<String> arguments) async {
 
   final currentDirUri = Uri.file(".");
   final buildPath =
-      options.buildDir ?? currentDirUri.resolve("src/build").toFilePath();
+      options.buildDir ?? currentDirUri.resolve("build/jni_libs").toFilePath();
   final buildDir = Directory(buildPath);
   await buildDir.create(recursive: true);
   log("buildPath: $buildPath");
@@ -136,15 +160,15 @@ void main(List<String> arguments) async {
 Future<void> build(Options options, String srcPath, String buildPath) async {
   final runner = CommandRunner(printCmds: true);
   final cmakeArgs = <String>[];
-  if (options.cmakeArgs != null) {
-    cmakeArgs.addAll(options.cmakeArgs!.split(" "));
-  }
+  cmakeArgs.addAll(options.cmakeArgs);
   cmakeArgs.add(srcPath);
   await runner.run("cmake", cmakeArgs, buildPath);
   await runner.run("cmake", ["--build", "."], buildPath);
   if (Platform.isWindows) {
     await runner.run("move", ["Debug\\dartjni.dll", "."], buildPath);
   }
+  // delete cmakeTemporaryArtifacts
+  deleteCMakeTemps(Uri.directory(buildPath));
 }
 
 Future<void> cleanup(Options options, String srcPath, String buildPath) async {

pkgs/jni/example/android/app/src/main/java/dev/dart/jni_example/AnyToast.java

@@ -1,28 +1,28 @@
 package dev.dart.jni_example;
 
 import android.app.Activity;
-import android.os.Handler;
 import android.content.Context;
 import android.widget.Toast;
 import androidx.annotation.Keep;
 
 @Keep
 class AnyToast {
-	static AnyToast makeText(Activity mainActivity, Context context, CharSequence text, int duration) {
-		AnyToast toast = new AnyToast();
-		toast.mainActivity = mainActivity;
-		toast.context = context;
-		toast.text = text;
-		toast.duration = duration;
-		return toast;
-	}
+  static AnyToast makeText(
+      Activity mainActivity, Context context, CharSequence text, int duration) {
+    AnyToast toast = new AnyToast();
+    toast.mainActivity = mainActivity;
+    toast.context = context;
+    toast.text = text;
+    toast.duration = duration;
+    return toast;
+  }
 
-	void show() {
-		mainActivity.runOnUiThread(() -> Toast.makeText(context, text, duration).show());
-	}
+  void show() {
+    mainActivity.runOnUiThread(() -> Toast.makeText(context, text, duration).show());
+  }
 
-	Activity mainActivity;
-	Context context;
-	CharSequence text;
-	int duration;
+  Activity mainActivity;
+  Context context;
+  CharSequence text;
+  int duration;
 }

pkgs/jni/example/test/widget_test.dart

@@ -14,7 +14,7 @@ import 'package:jni_example/main.dart';
 
 void main() {
   if (!Platform.isAndroid) {
-    Jni.spawn(helperDir: "../src/build");
+    Jni.spawn(helperDir: "build/jni_libs");
   }
   final jni = Jni.getInstance();
   testWidgets("simple toString example", (tester) async {

pkgs/jni/lib/jni.dart

@@ -64,3 +64,4 @@ export 'src/jvalues.dart' hide JValueArgs, toJValues;
 export 'src/extensions.dart'
     show StringMethodsForJni, CharPtrMethodsForJni, AdditionalJniEnvMethods;
 export 'src/jni_exceptions.dart';
+export 'src/jl_object.dart';

pkgs/jni/lib/src/jl_object.dart

@@ -0,0 +1,61 @@
+import 'dart:ffi';
+
+import 'package:ffi/ffi.dart';
+
+import 'third_party/jni_bindings_generated.dart';
+import 'jni_exceptions.dart';
+import 'jni.dart';
+
+/// A container for a global [JObject] reference.
+class JlObject {
+  /// Constructs a `JlObject` from JNI reference.
+  JlObject.fromRef(this.reference);
+
+  /// Stored JNI global reference to the object.
+  JObject reference;
+
+  bool _deleted = false;
+
+  /// Deletes the underlying JNI reference.
+  ///
+  /// Must be called after this object is no longer needed.
+  void delete() {
+    if (_deleted) {
+      throw DoubleFreeException(this, reference);
+    }
+    _deleted = true;
+    // TODO(#12): this should be done in jni-thread-safe way
+    // will be solved when #12 is implemented.
+    Jni.getInstance().getEnv().DeleteGlobalRef(reference);
+  }
+}
+
+/// A container for JNI strings, with convertion to & from dart strings.
+class JlString extends JlObject {
+  JlString.fromRef(JString reference) : super.fromRef(reference);
+
+  static JString _toJavaString(String s) {
+    final chars = s.toNativeUtf8().cast<Char>();
+    final jstr = Jni.getInstance().toJavaString(chars);
+    malloc.free(chars);
+    return jstr;
+  }
+
+  JlString.fromString(String s) : super.fromRef(_toJavaString(s));
+
+  String toDartString() {
+    final jni = Jni.getInstance();
+    if (reference == nullptr) {
+      throw NullJlStringException();
+    }
+    final chars = jni.getJavaStringChars(reference);
+    final result = chars.cast<Utf8>().toDartString();
+    jni.releaseJavaStringChars(reference, chars);
+    return result;
+  }
+
+  late final _dartString = toDartString();
+
+  @override
+  String toString() => _dartString;
+}