Dart Isolates As Workers

Question

Edited to make the question more clear.

I am trying to work with Isolates (or Web Workers) in Dart. The only ways I can find to communicate between the

Answer 1

Here is an example where parent creates two isolates and then two isolates also talk to each other along with the parent process.

Parent Code:

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

main() {
  querySelector('#output').text = 'Your Dart app is running.';
  int counter = 0;

  // Parent - Child 1
  SendPort csendPort1;
  ReceivePort receivePort1 = new ReceivePort();
  // Parent - Child 2
  SendPort csendPort2;
  ReceivePort receivePort2 = new ReceivePort();
  // Child1 - Child2
  SendPort csendPort11;
  SendPort csendPort12;

  // Child 1
  receivePort1.listen((msg) {
    if (csendPort1 == null) {
      csendPort1 = msg;
    } else if (csendPort11 == null) {
      csendPort11 = msg;
    } else {
      print('$msg');`enter code here`
    }
  });

  bool child1 = false;
  Isolate.spawnUri(Uri.parse('child.dart'), [], receivePort1.sendPort).then((isolate) {
    print('Child 1 isolate spawned');
    new Timer.periodic(const Duration(milliseconds: 500), (t) {
      if (csendPort11 != null && csendPort12 != null && child1 == false) {
        child1 = true;
        csendPort12.send(csendPort11);
      } else {
        csendPort1.send('Parent-Child1: ${counter++}');
      }
    });
  });

  // Child 2
  receivePort2.listen((msg) {
    if (csendPort2 == null) {
      csendPort2 = msg;
    } else if (csendPort12 == null) {
      csendPort12 = msg;
    } else {
      print('$msg');
    }
  });

  bool child2 = false;
  Isolate.spawnUri(Uri.parse('child.dart'), [], receivePort2.sendPort).then((isolate) {
    print('Child 2 isolate spawned');
    new Timer.periodic(const Duration(milliseconds: 500), (t) {
      if (csendPort11 != null && csendPort12 != null && child2 == false) {
        child2 = true;
        csendPort11.send(csendPort12);
      } else {
        csendPort2.send('Parent-Child2: ${counter++}');
      }
    });
  });
}

Child Code:

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

int pcounter = 0;
int ccounter = 0;

SendPort csendPort;
void handleTimeout() {
  csendPort.send("${ccounter++}");
}

main(List args, SendPort psendPort) {
  // Parent Comm
  ReceivePort creceivePort1 = new ReceivePort();
  psendPort.send(creceivePort1.sendPort);

  creceivePort1.listen((msg) {
    psendPort.send('Child-Parent: ${pcounter++} - ${msg}');
  });

  // Child-Child Comm
  ReceivePort creceivePort2 = new ReceivePort();
  psendPort.send(creceivePort2.sendPort);

  creceivePort2.listen((msg) {
    if (csendPort == null) {
      csendPort = msg;
      csendPort.send("${ccounter++}");
    } else {
      print("Child-Child: $msg");
      var duration = const Duration(milliseconds: 2000);
      new Timer(duration, handleTimeout);
    }
  });
}

HTML Code: