LibTest/isolate/Isolate/pause_A01_t02.dart

// Copyright (c) 2017, 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.

// @dart = 2.9

/// @assertion Capability pause([
///    Capability resumeCapability
/// ])
///    Requests the isolate to pause.
///    When the isolate receives the pause command, it stops processing events
/// from the event loop queue. It may still add new events to the queue in
/// response to, e.g., timers or receive-port messages. When the isolate is
/// resumed, it handles the already enqueued events.
///
/// @description Check that pause() with given capability does not stop the
/// isolate to execute code.
///
/// @author a.semenov@unipro.ru

import "dart:isolate";
import "dart:math";
import "../../../Utils/expect.dart";

// indefinitely running isolate
entryPoint(SendPort sendPort){
  Random random = new Random();
  int s = 0;
  while (true){
    s = -s + random.nextInt(100);
    sendPort.send(s);
  }
}

test() async {
  ReceivePort receivePort = new ReceivePort();
  ReceivePort onExit = new ReceivePort();
  Isolate isolate = await Isolate.spawn(
      entryPoint,
      receivePort.sendPort, // message
      onExit:onExit.sendPort,
      errorsAreFatal:true
  );
  isolate.pause(new Capability());
  // check that messages are received from paused isolate
  int count = 0;
  await for (var _ in receivePort){
    if (count++==1000000){
      break;
    }
  }
  // clean up
  isolate.kill(priority:Isolate.immediate);
  await onExit.first;
  asyncEnd();
}

main() {
  asyncStart();
  test();
}