[jnigen] Fix sync suspend funs from hanging (#2028)

HosseinYousefi · web-flow · commit ae32a51b3915 · 2025-02-25T12:01:06.000+01:00
* [jnigen] Fix sync `suspend fun`s from hanging

* Handle thrown exceptions from suspend funs
diff --git a/pkgs/jni/CHANGELOG.md b/pkgs/jni/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 - Updated `bin/setup.dart` to use Gradle instead of Maven for building Java sources. Added gradle executables 
   and bootstrap jars [#2003](https://github.com/dart-lang/native/issues/2003)
+- Added `JObject.isInstanceOf` which checks whether a `JObject` is an instance 
+  of a java class.
 
 ## 0.14.0
 
@@ -14,8 +16,8 @@
   instead use the default value of `build/jni_libs`.
 - Added `JArray.of`, which allows a `JArray` to be constructed from an
   `Iterable`.
-- Added `JObject.isA`, which checks whether a `JObject` is a instance of a java
-  class.
+- Added `JObject.isA`, which checks whether a `JObject` is an instance of a java
+  typeclass.
 - Do not require JAWT when building for desktop.
 - Added `JByteArray.from`, which allows a `JByteArray` to be constructed from an
   `Iterable<int>`.
diff --git a/pkgs/jni/lib/_internal.dart b/pkgs/jni/lib/_internal.dart
@@ -30,6 +30,8 @@ export 'package:meta/meta.dart' show internal;
 export 'src/accessors.dart';
 export 'src/jni.dart' show ProtectedJniExtensions;
 export 'src/jreference.dart';
+export 'src/kotlin.dart'
+    show coroutineSingletonsClass, failureExceptionField, result$FailureClass;
 export 'src/method_invocation.dart';
 export 'src/types.dart'
     show
diff --git a/pkgs/jni/lib/src/jni.dart b/pkgs/jni/lib/src/jni.dart
@@ -183,6 +183,7 @@ abstract final class Jni {
 
   /// Throws an exception.
   // TODO(#561): Throw an actual `JThrowable`.
+  @internal
   static void throwException(JThrowablePtr exception) {
     final details = _bindings.GetExceptionDetails(exception);
     final env = Jni.env;
diff --git a/pkgs/jni/lib/src/jobject.dart b/pkgs/jni/lib/src/jobject.dart
@@ -148,12 +148,17 @@ class JObject {
   /// }
   /// ```
   bool isA<T extends JObject?>(JObjType<T> type) {
-    final targetJClass = type.jClass.reference.toPointer();
-    final canBeCasted = Jni.env.IsInstanceOf(reference.pointer, targetJClass);
-    Jni.env.DeleteGlobalRef(targetJClass);
+    final targetJClass = type.jClass;
+    final canBeCasted = isInstanceOf(targetJClass);
+    targetJClass.release();
     return canBeCasted;
   }
 
+  /// Whether this object is of the type of the given [jclass].
+  bool isInstanceOf(JClass jclass) {
+    return Jni.env.IsInstanceOf(reference.pointer, jclass.reference.pointer);
+  }
+
   /// Casts this object to another [type].
   ///
   /// If [releaseOriginal] is `true`, the casted object will be released.
diff --git a/pkgs/jni/lib/src/kotlin.dart b/pkgs/jni/lib/src/kotlin.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2025, 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:meta/meta.dart' show internal;
+
+import 'types.dart';
+
+@internal
+final coroutineSingletonsClass =
+    JClass.forName('kotlin/coroutines/intrinsics/CoroutineSingletons');
+
+@internal
+final result$FailureClass = JClass.forName(r'kotlin/Result$Failure');
+
+@internal
+final failureExceptionField =
+    result$FailureClass.instanceFieldId('exception', 'Ljava/lang/Throwable;');
diff --git a/pkgs/jnigen/CHANGELOG.md b/pkgs/jnigen/CHANGELOG.md
@@ -3,6 +3,8 @@
 - Added support for generating matching Kotlin operators as Dart operators.
 - Include the methods of the superinterfaces of a class or interface in the
   bindings.
+- Fix a bug where Kotlin suspendable functions that returned the result without
+  ever suspending would timeout in Dart.
 - Retrieval of dependencies uses Gradle (`GradleTools`) en lieu of Maven (`MavenTools`).
 - Updated `bin\download_maven_jars.dart` to use `GradleTools`.
 
diff --git a/pkgs/jnigen/example/kotlin_plugin/lib/kotlin_bindings.dart b/pkgs/jnigen/example/kotlin_plugin/lib/kotlin_bindings.dart
@@ -98,22 +98,27 @@ class Example extends jni$_.JObject {
     final $p = jni$_.ReceivePort();
     final _$continuation = jni$_.ProtectedJniExtensions.newPortContinuation($p);
 
-    _thinkBeforeAnswering(
+    final $r = _thinkBeforeAnswering(
             reference.pointer,
             _id_thinkBeforeAnswering as jni$_.JMethodIDPtr,
             _$continuation.pointer)
-        .object<jni$_.JObject>(const jni$_.JObjectType())
-        .release();
+        .object<jni$_.JObject>(const jni$_.JObjectType());
     _$continuation.release();
-    final $o =
-        jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first));
-    final $k = const jni$_.JStringType().jClass.reference;
-    if (!jni$_.Jni.env.IsInstanceOf($o.pointer, $k.pointer)) {
-      $k.release();
-      throw 'Failed';
+    final jni$_.JObject $o;
+    if ($r.isInstanceOf(jni$_.coroutineSingletonsClass)) {
+      $r.release();
+      $o = jni$_.JObject.fromReference(
+          jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first)));
+      if ($o.isInstanceOf(jni$_.result$FailureClass)) {
+        final $e =
+            jni$_.failureExceptionField.get($o, const jni$_.JObjectType());
+        $o.release();
+        jni$_.Jni.throwException($e.reference.toPointer());
+      }
+    } else {
+      $o = $r;
     }
-    $k.release();
-    return const jni$_.JStringType().fromReference($o);
+    return $o.as(const jni$_.JStringType(), releaseOriginal: true);
   }
 }
 
diff --git a/pkgs/jnigen/lib/src/bindings/dart_generator.dart b/pkgs/jnigen/lib/src/bindings/dart_generator.dart
@@ -1418,9 +1418,6 @@ ${modifier}final _$name = $_protectedExtension
         ? '$_core.Future<'
             '${node.asyncReturnType!.accept(_TypeGenerator(resolver))}>'
         : node.returnType.accept(_TypeGenerator(resolver));
-    final returnTypeClass = (node.asyncReturnType ?? node.returnType)
-        .accept(_TypeClassGenerator(resolver))
-        .name;
     final ifStatic = node.isStatic && !isTopLevel ? 'static ' : '';
     final defArgs = node.params.accept(_ParamDef(resolver)).toList();
     final typeClassDef = node.typeParams
@@ -1451,16 +1448,23 @@ ${modifier}final _$name = $_protectedExtension
     final \$p = $_jni.ReceivePort();
     final _\$$continuation = $_protectedExtension.newPortContinuation(\$p);
     ${localReferences.join(_newLine(depth: 2))}
-    $callExpr.release();
+    final \$r = $callExpr;
     _\$$continuation.release();
-    final \$o = $_jGlobalReference($_jPointer.fromAddress(await \$p.first));
-    final \$k = $returnTypeClass.jClass.reference;
-    if (!$_jni.Jni.env.IsInstanceOf(\$o.pointer, \$k.pointer)) {
-      \$k.release();
-      throw 'Failed';
+    final $_jObject \$o;
+    if (\$r.isInstanceOf($_jni.coroutineSingletonsClass)) {
+      \$r.release();
+      \$o = $_jObject.fromReference(
+          $_jGlobalReference($_jPointer.fromAddress(await \$p.first)));
+      if (\$o.isInstanceOf($_jni.result\$FailureClass)) {
+        final \$e =
+            $_jni.failureExceptionField.get(\$o, const ${_jObject}Type());
+        \$o.release();
+        $_jni.Jni.throwException(\$e.reference.toPointer());
+      }
+    } else {
+      \$o = \$r;
     }
-    \$k.release();
-    return $returningType.fromReference(\$o);
+    return \$o.as($returningType, releaseOriginal: true);
   }
 
 ''');
diff --git a/pkgs/jnigen/lib/src/bindings/renamer.dart b/pkgs/jnigen/lib/src/bindings/renamer.dart
@@ -95,6 +95,8 @@ const Map<String, int> _definedSyms = {
   'runtimeType': 1,
   'noSuchMethod': 1,
   'reference': 1,
+  'isA': 1,
+  'isInstanceOf': 1,
   'isReleased': 1,
   'isNull': 1,
   'use': 1,
diff --git a/pkgs/jnigen/test/kotlin_test/bindings/kotlin.dart b/pkgs/jnigen/test/kotlin_test/bindings/kotlin.dart
@@ -2630,6 +2630,137 @@ class SuspendFun extends jni$_.JObject {
             .reference);
   }
 
+  static final _id_sayHelloWithoutDelay = _class.instanceMethodId(
+    r'sayHelloWithoutDelay',
+    r'(Lkotlin/coroutines/Continuation;)Ljava/lang/Object;',
+  );
+
+  static final _sayHelloWithoutDelay = jni$_.ProtectedJniExtensions.lookup<
+              jni$_.NativeFunction<
+                  jni$_.JniResult Function(
+                      jni$_.Pointer<jni$_.Void>,
+                      jni$_.JMethodIDPtr,
+                      jni$_.VarArgs<(jni$_.Pointer<jni$_.Void>,)>)>>(
+          'globalEnv_CallObjectMethod')
+      .asFunction<
+          jni$_.JniResult Function(jni$_.Pointer<jni$_.Void>,
+              jni$_.JMethodIDPtr, jni$_.Pointer<jni$_.Void>)>();
+
+  /// from: `public final java.lang.Object sayHelloWithoutDelay(kotlin.coroutines.Continuation continuation)`
+  /// The returned object must be released after use, by calling the [release] method.
+  core$_.Future<jni$_.JString> sayHelloWithoutDelay() async {
+    final $p = jni$_.ReceivePort();
+    final _$continuation = jni$_.ProtectedJniExtensions.newPortContinuation($p);
+
+    final $r = _sayHelloWithoutDelay(
+            reference.pointer,
+            _id_sayHelloWithoutDelay as jni$_.JMethodIDPtr,
+            _$continuation.pointer)
+        .object<jni$_.JObject>(const jni$_.JObjectType());
+    _$continuation.release();
+    final jni$_.JObject $o;
+    if ($r.isInstanceOf(jni$_.coroutineSingletonsClass)) {
+      $r.release();
+      $o = jni$_.JObject.fromReference(
+          jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first)));
+      if ($o.isInstanceOf(jni$_.result$FailureClass)) {
+        final $e =
+            jni$_.failureExceptionField.get($o, const jni$_.JObjectType());
+        $o.release();
+        jni$_.Jni.throwException($e.reference.toPointer());
+      }
+    } else {
+      $o = $r;
+    }
+    return $o.as(const jni$_.JStringType(), releaseOriginal: true);
+  }
+
+  static final _id_failWithoutDelay = _class.instanceMethodId(
+    r'failWithoutDelay',
+    r'(Lkotlin/coroutines/Continuation;)Ljava/lang/Object;',
+  );
+
+  static final _failWithoutDelay = jni$_.ProtectedJniExtensions.lookup<
+              jni$_.NativeFunction<
+                  jni$_.JniResult Function(
+                      jni$_.Pointer<jni$_.Void>,
+                      jni$_.JMethodIDPtr,
+                      jni$_.VarArgs<(jni$_.Pointer<jni$_.Void>,)>)>>(
+          'globalEnv_CallObjectMethod')
+      .asFunction<
+          jni$_.JniResult Function(jni$_.Pointer<jni$_.Void>,
+              jni$_.JMethodIDPtr, jni$_.Pointer<jni$_.Void>)>();
+
+  /// from: `public final java.lang.Object failWithoutDelay(kotlin.coroutines.Continuation continuation)`
+  /// The returned object must be released after use, by calling the [release] method.
+  core$_.Future<jni$_.JString> failWithoutDelay() async {
+    final $p = jni$_.ReceivePort();
+    final _$continuation = jni$_.ProtectedJniExtensions.newPortContinuation($p);
+
+    final $r = _failWithoutDelay(reference.pointer,
+            _id_failWithoutDelay as jni$_.JMethodIDPtr, _$continuation.pointer)
+        .object<jni$_.JObject>(const jni$_.JObjectType());
+    _$continuation.release();
+    final jni$_.JObject $o;
+    if ($r.isInstanceOf(jni$_.coroutineSingletonsClass)) {
+      $r.release();
+      $o = jni$_.JObject.fromReference(
+          jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first)));
+      if ($o.isInstanceOf(jni$_.result$FailureClass)) {
+        final $e =
+            jni$_.failureExceptionField.get($o, const jni$_.JObjectType());
+        $o.release();
+        jni$_.Jni.throwException($e.reference.toPointer());
+      }
+    } else {
+      $o = $r;
+    }
+    return $o.as(const jni$_.JStringType(), releaseOriginal: true);
+  }
+
+  static final _id_fail = _class.instanceMethodId(
+    r'fail',
+    r'(Lkotlin/coroutines/Continuation;)Ljava/lang/Object;',
+  );
+
+  static final _fail = jni$_.ProtectedJniExtensions.lookup<
+              jni$_.NativeFunction<
+                  jni$_.JniResult Function(
+                      jni$_.Pointer<jni$_.Void>,
+                      jni$_.JMethodIDPtr,
+                      jni$_.VarArgs<(jni$_.Pointer<jni$_.Void>,)>)>>(
+          'globalEnv_CallObjectMethod')
+      .asFunction<
+          jni$_.JniResult Function(jni$_.Pointer<jni$_.Void>,
+              jni$_.JMethodIDPtr, jni$_.Pointer<jni$_.Void>)>();
+
+  /// from: `public final java.lang.Object fail(kotlin.coroutines.Continuation continuation)`
+  /// The returned object must be released after use, by calling the [release] method.
+  core$_.Future<jni$_.JString> fail() async {
+    final $p = jni$_.ReceivePort();
+    final _$continuation = jni$_.ProtectedJniExtensions.newPortContinuation($p);
+
+    final $r = _fail(reference.pointer, _id_fail as jni$_.JMethodIDPtr,
+            _$continuation.pointer)
+        .object<jni$_.JObject>(const jni$_.JObjectType());
+    _$continuation.release();
+    final jni$_.JObject $o;
+    if ($r.isInstanceOf(jni$_.coroutineSingletonsClass)) {
+      $r.release();
+      $o = jni$_.JObject.fromReference(
+          jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first)));
+      if ($o.isInstanceOf(jni$_.result$FailureClass)) {
+        final $e =
+            jni$_.failureExceptionField.get($o, const jni$_.JObjectType());
+        $o.release();
+        jni$_.Jni.throwException($e.reference.toPointer());
+      }
+    } else {
+      $o = $r;
+    }
+    return $o.as(const jni$_.JStringType(), releaseOriginal: true);
+  }
+
   static final _id_sayHello = _class.instanceMethodId(
     r'sayHello',
     r'(Lkotlin/coroutines/Continuation;)Ljava/lang/Object;',
@@ -2652,20 +2783,25 @@ class SuspendFun extends jni$_.JObject {
     final $p = jni$_.ReceivePort();
     final _$continuation = jni$_.ProtectedJniExtensions.newPortContinuation($p);
 
-    _sayHello(reference.pointer, _id_sayHello as jni$_.JMethodIDPtr,
+    final $r = _sayHello(reference.pointer, _id_sayHello as jni$_.JMethodIDPtr,
             _$continuation.pointer)
-        .object<jni$_.JObject>(const jni$_.JObjectType())
-        .release();
+        .object<jni$_.JObject>(const jni$_.JObjectType());
     _$continuation.release();
-    final $o =
-        jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first));
-    final $k = const jni$_.JStringType().jClass.reference;
-    if (!jni$_.Jni.env.IsInstanceOf($o.pointer, $k.pointer)) {
-      $k.release();
-      throw 'Failed';
+    final jni$_.JObject $o;
+    if ($r.isInstanceOf(jni$_.coroutineSingletonsClass)) {
+      $r.release();
+      $o = jni$_.JObject.fromReference(
+          jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first)));
+      if ($o.isInstanceOf(jni$_.result$FailureClass)) {
+        final $e =
+            jni$_.failureExceptionField.get($o, const jni$_.JObjectType());
+        $o.release();
+        jni$_.Jni.throwException($e.reference.toPointer());
+      }
+    } else {
+      $o = $r;
     }
-    $k.release();
-    return const jni$_.JStringType().fromReference($o);
+    return $o.as(const jni$_.JStringType(), releaseOriginal: true);
   }
 
   static final _id_sayHello$1 = _class.instanceMethodId(
@@ -2698,20 +2834,28 @@ class SuspendFun extends jni$_.JObject {
     final $p = jni$_.ReceivePort();
     final _$continuation = jni$_.ProtectedJniExtensions.newPortContinuation($p);
     final _$string = string.reference;
-    _sayHello$1(reference.pointer, _id_sayHello$1 as jni$_.JMethodIDPtr,
-            _$string.pointer, _$continuation.pointer)
-        .object<jni$_.JObject>(const jni$_.JObjectType())
-        .release();
+    final $r = _sayHello$1(
+            reference.pointer,
+            _id_sayHello$1 as jni$_.JMethodIDPtr,
+            _$string.pointer,
+            _$continuation.pointer)
+        .object<jni$_.JObject>(const jni$_.JObjectType());
     _$continuation.release();
-    final $o =
-        jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first));
-    final $k = const jni$_.JStringType().jClass.reference;
-    if (!jni$_.Jni.env.IsInstanceOf($o.pointer, $k.pointer)) {
-      $k.release();
-      throw 'Failed';
+    final jni$_.JObject $o;
+    if ($r.isInstanceOf(jni$_.coroutineSingletonsClass)) {
+      $r.release();
+      $o = jni$_.JObject.fromReference(
+          jni$_.JGlobalReference(jni$_.JObjectPtr.fromAddress(await $p.first)));
+      if ($o.isInstanceOf(jni$_.result$FailureClass)) {
+        final $e =
+            jni$_.failureExceptionField.get($o, const jni$_.JObjectType());
+        $o.release();
+        jni$_.Jni.throwException($e.reference.toPointer());
+      }
+    } else {
+      $o = $r;
     }
-    $k.release();
-    return const jni$_.JStringType().fromReference($o);
+    return $o.as(const jni$_.JStringType(), releaseOriginal: true);
   }
 }
 
diff --git a/pkgs/jnigen/test/kotlin_test/kotlin/src/main/kotlin/com/github/dart_lang/jnigen/SuspendFun.kt b/pkgs/jnigen/test/kotlin_test/kotlin/src/main/kotlin/com/github/dart_lang/jnigen/SuspendFun.kt
diff --git a/pkgs/jnigen/test/kotlin_test/runtime_test_registrant.dart b/pkgs/jnigen/test/kotlin_test/runtime_test_registrant.dart
