[jnigen] Debugging CI flake

.github/workflows/jnigen.yaml

@@ -143,11 +143,14 @@ jobs:
         run: dart run jnigen:setup
       - name: Run VM tests
         run: |
-          if [ "${{ matrix.java-version }}" != "17" ]; then
-            dart test -x bindings --test-randomize-ordering-seed random
-          else
-            dart test --test-randomize-ordering-seed random
-          fi
+          for i in $(seq 1 10); do
+            echo "=== Iteration $i ==="
+            if [ "${{ matrix.java-version }}" != "17" ]; then
+              dart test -x bindings --test-randomize-ordering-seed random || exit 1
+            else
+              dart test --test-randomize-ordering-seed random || exit 1
+            fi
+          done
       - name: build in_app_java APK
         run: flutter build apk --target-platform=android-arm64
         working-directory: ./pkgs/jnigen/example/in_app_java

pkgs/jnigen/pubspec.yaml

@@ -35,6 +35,7 @@ dependencies:
 dev_dependencies:
   build_runner: ^2.4.12
   dart_flutter_team_lints: ^3.5.2
+  ffi: ^2.1.3
   jni:
     path: ../jni
   json_serializable: ^6.8.0

pkgs/jnigen/test/simple_package_test/runtime_test_registrant.dart

@@ -719,6 +719,19 @@ void registerTests(String groupName, TestRunnerCallback test) {
         });
 
         group('Interface implementation on destroyed isolate', () {
+          Future<void> waitUntilCollected(MyConsumerRunner runner) async {
+            for (var i = 0; i < 8; ++i) {
+              if (i > 0) {
+                await Future<void>.delayed(
+                    Duration(milliseconds: (1 << i) * 100));
+              }
+              await runBothGC();
+              if (runner.isArgCollected) {
+                return;
+              }
+            }
+          }
+
           test('non-blocking callback - successful callback flow', () async {
             final runnerPort = ReceivePort();
             final callbackPort = ReceivePort();
@@ -740,12 +753,12 @@ void registerTests(String groupName, TestRunnerCallback test) {
 
             final result = await callbackPort.first;
             expect(result, 'callback_executed');
-            expect(runner.isFinished, isTrue);
+            expect(runner.waitForFinished(1000), isTrue);
 
             isolate.kill(priority: Isolate.immediate);
             await exitPort.first;
 
-            runJavaGC();
+            await waitUntilCollected(runner);
             expect(runner.isArgCollected, isTrue);
           });
 
@@ -773,14 +786,14 @@ void registerTests(String groupName, TestRunnerCallback test) {
             arg.release();
 
             // Runner finished even though message isn't delivered.
-            expect(runner.isFinished, isTrue);
+            expect(runner.waitForFinished(1000), isTrue);
             expect(
               callbackPort.first.timeout(const Duration(milliseconds: 200)),
               throwsA(isA<TimeoutException>()),
             );
 
             // Arg is cleaned up even though message isn't delivered.
-            runJavaGC();
+            await waitUntilCollected(runner);
             expect(runner.isArgCollected, isTrue);
           });
 
@@ -817,7 +830,7 @@ void registerTests(String groupName, TestRunnerCallback test) {
             );
 
             // Arg is cleaned up even though message isn't delivered.
-            runJavaGC();
+            await waitUntilCollected(runner);
             expect(runner.isArgCollected, isTrue);
           });
 
@@ -847,7 +860,7 @@ void registerTests(String groupName, TestRunnerCallback test) {
             isolate.kill(priority: Isolate.immediate);
             await exitPort.first;
 
-            runJavaGC();
+            await waitUntilCollected(runner);
             expect(runner.isArgCollected, isTrue);
           });
 
@@ -882,7 +895,7 @@ void registerTests(String groupName, TestRunnerCallback test) {
             );
 
             // Arg is cleaned up even though message isn't delivered.
-            runJavaGC();
+            await waitUntilCollected(runner);
             expect(runner.isArgCollected, isTrue);
           });
 
@@ -919,10 +932,10 @@ void registerTests(String groupName, TestRunnerCallback test) {
             );
 
             // Arg is cleaned up even though message isn't delivered.
-            runJavaGC();
+            await waitUntilCollected(runner);
             expect(runner.isArgCollected, isTrue);
           });
-        }, skip: !canRunJavaGC);
+        }, skip: !canRunJavaGC || !canDoGC);
       }
 
       group('Dart exceptions are handled', () {

pkgs/jnigen/test/test_util/java_gc.dart

@@ -5,7 +5,7 @@
 import 'dart:ffi';
 import 'dart:io';
 
-import 'package:jni/_internal.dart';
+import 'package:ffi/ffi.dart';
 import 'package:jni/jni.dart';
 
 // Can't reliably force GC on Android.
@@ -30,6 +30,34 @@ void runJavaGC() {
   } while (result.exitCode != 0);
 }
 
+final _executeInternalCommand = () {
+  final dylib = DynamicLibrary.process();
+  if (dylib.providesSymbol('Dart_ExecuteInternalCommand')) {
+    return dylib
+        .lookup<NativeFunction<Void Function(Pointer<Char>, Pointer<Void>)>>(
+          'Dart_ExecuteInternalCommand',
+        )
+        .asFunction<void Function(Pointer<Char>, Pointer<Void>)>();
+  }
+  return null;
+}();
+
+final canDoGC = _executeInternalCommand != null;
+
+void runDartGC() {
+  if (_executeInternalCommand == null) return;
+  final gcNow = 'gc-now'.toNativeUtf8();
+  _executeInternalCommand!(gcNow.cast(), nullptr);
+  calloc.free(gcNow);
+}
+
+Future<void> runBothGC() async {
+  runDartGC();
+  await Future<void>.delayed(Duration.zero);
+  runDartGC();
+  runJavaGC();
+}
+
 /// A wrapper around Java's `java.lang.ref.WeakReference` for testing GC
 /// collection.
 class JWeakReference {