locking 0.0.9

The "locking" prevents the simultaneous execution of the "locked" code in the different zones.

locking

The "locking" prevents the simultaneous execution of the "locked" code in the different zones.

Version: 0.0.

Current implementation of locking:

final Expando _mutexes = new Expando();

Future lock(Object object, void action()) async {
  ReentrantMutex mutex = _mutexes[object];
  if (mutex == null) {
    mutex = new ReentrantMutex();
    _mutexes[object] = mutex;
  }

  await mutex.acquire();
  try {
    await action();
  } finally {
    mutex.release();
  }
}

Example:

import "dart:async";

import "package:locking/lock.dart";

Future main() async {
  print("=================");
  print("Different zones");
  print("=================");
  var t1 = task("task 0", 800);
  var t2 = task("task 1", 400);
  var t3 = runZoned(() => task("task 2", 200));
  var t4 = runZoned(() => task("task 3", 100));
  await Future.wait([t1, t2, t3, t4]);

  print("=================");
  print("The same zone");
  print("=================");
  t1 = task("task 0", 800);
  t2 = task("task 1", 400);
  t3 = task("task 2", 200);
  t4 = task("task 3", 100);
  await Future.wait([t1, t2, t3, t4]);
}

Object _obj = new Object();

List _running = [];

Future task(String name, int ms) async {
  await lock(_obj, () async {
    _running.add(name);
    print("$name: [${_running.join(", ")}]");
    await sleep(new Duration(milliseconds: ms));    
    _running.remove(name);
    print("$name: finished");
  });
}

Output:

=================
Different zones
=================
task 0: [task 0]
task 1: [task 0, task 1]
task 1: finished
task 0: finished
task 2: [task 2]
task 2: finished
task 3: [task 3]
task 3: finished
=================
The same zone
=================
task 0: [task 0]
task 1: [task 0, task 1]
task 2: [task 0, task 1, task 2]
task 3: [task 0, task 1, task 2, task 3]
task 3: finished
task 2: finished
task 1: finished
task 0: finished