flutter_isolate_spawn

flutter_isolate_spawn.dart

import 'dart:async';
import 'dart:isolate';

void main() async {
  // 1. Create the main receive port.
  final mainReceivePort = ReceivePort();
  // 2. Spawn an isolate with the main send port.
  final newIsolate = await Isolate.spawn(createNewIsolate, mainReceivePort.sendPort);

  mainReceivePort.listen((message) {
    // 5. Receive send port of the new isolate.
    if (message is SendPort) {
      // 6. Send value to new isolate.
      int value = 1;
      print("main Isolate: Message sent to new Isolate: $value");
      message.send(value);
    } else {
      // 9. Receive the result.
      print("main Isolate: Received message from new Isolate: $message");
    }
  });
}

void createNewIsolate(SendPort mainSendPort) {
  // 3. Create a receive port in the new Isolate.
  final isolateReceivePort = ReceivePort();
  // 4. Send send port of the new isolate back to main isolate.
  mainSendPort.send(isolateReceivePort.sendPort);
  isolateReceivePort.listen((message) async {
    print("new Isolate: Received message from main Isolate: $message");
    // 7. Receive value from main isolate.
    if (message is int) {
      // 8. Do the task and send the result back to main isolate.
      final result = await heavyTask(message);
      print("new Isolate: Message sent to main Isolate: result");
      mainSendPort.send(result);
    }
  });
}

Future<int> heavyTask(int value) => Future.delayed(const Duration(seconds: 3), () => value + 1);