fix: Prevent creation of multiple isolates when IrisMethodChannel.ini…

…tialize is called multiple times simultaneously

lib/src/iris_method_channel.dart

@@ -10,16 +10,20 @@ import 'package:iris_method_channel/src/platform/iris_method_channel_internal.da
 
 class CallOnce {
   Completer<void> _completer = Completer<void>();
+  bool _isRunning = false;
 
   Future<void> callOnce(Future<void> Function() func) async {
-    if (!_completer.isCompleted) {
+    if (!_completer.isCompleted && !_isRunning) {
       try {
+        _isRunning = true;
         await func();
       } catch (e) {
         _completer = Completer<void>();
+        _isRunning = false;
         rethrow;
       }
       _completer.complete();
+      _isRunning = false;
     }
     return _completer.future;
   }

test/iris_method_channel_test.dart

@@ -83,6 +83,19 @@ void main() {
     await irisMethodChannel.dispose();
   });
 
+  test('only initialize once when called simultaneously', () async {
+    for (int i = 0; i < 5; ++i) {
+      irisMethodChannel.initilize([]);
+    }
+    // Wait for the 5 times calls of `irisMethodChannel.initilize` are completed.
+    await Future.delayed(const Duration(milliseconds: 1000));
+    final callRecord1 = messenger.callApiRecords
+        .where((e) => e.methodCall.funcName == 'createApiEngine');
+    expect(callRecord1.length, 1);
+
+    await irisMethodChannel.dispose();
+  });
+
   test('can re-initialize after dispose', () async {
     await irisMethodChannel.initilize([]);
     await irisMethodChannel.initilize([]);