public void Creating_a_mutex_acquires_lock()
{
// Arrange
var mutexName = "myname";
// Act
using (var mutex = new Mutex(mutexName))
{
// Assert
mutex.Name.ShouldBe(mutexName);
MutexManager.Mutexes.ContainsKey(mutexName).ShouldBeTrue();
MutexManager.Mutexes[mutexName].State.ShouldBe(MutexState.Acquired);
MutexManager.Mutexes[mutexName].Timestamp.ShouldBeGreaterThan(DateTime.MinValue);
MutexManager.Mutexes[mutexName].ThreadId.ShouldBe(Thread.CurrentThread.ManagedThreadId);
}
// Assert
MutexManager.Mutexes.ContainsKey(mutexName).ShouldBeFalse();
}
public void Competing_threads_block_on_same_mutex()
{
// Arrange
var starts = new ConcurrentDictionary <string, DateTime>();
var stops = new ConcurrentDictionary <string, DateTime>();
var mutexCreate = new Action <string, string, int>((id, mutexName, timeoutSeconds) =>
{
var ok = false;
using (var mutex = new Mutex(mutexName))
{
starts.GetOrAdd(id, DateTime.UtcNow);
Console.WriteLine("{0} started at {1}", id, starts[id]);
Thread.Sleep(TimeSpan.FromSeconds(timeoutSeconds));
stops.GetOrAdd(id, DateTime.UtcNow);
Console.WriteLine("{0} stopped at {1}", id, stops[id]);
ok = true;
}
ok.ShouldBeTrue();
});
var threadStart1 = new ThreadStart(() => mutexCreate("1", "Bob", 3));
var threadStart2 = new ThreadStart(() => mutexCreate("2", "Bob", 2));
var threadStart3 = new ThreadStart(() => mutexCreate("3", "Bob", 1));
var threadStart4 = new ThreadStart(() => mutexCreate("4", "Jim", 2));
// Act
var thread1 = ThreadHelper.Start(threadStart1);
var thread2 = ThreadHelper.Start(threadStart2);
var thread3 = ThreadHelper.Start(threadStart3);
var thread4 = ThreadHelper.Start(threadStart4);
thread1.Join();
thread2.Join();
thread3.Join();
thread4.Join();
// Assert
starts.Count.ShouldBe(4);
stops.Count.ShouldBe(4);
var keys = starts
.Where(s => s.Key != "4") // Bob only
.OrderBy(s => s.Value)
.Select(s => s.Key);
var lastStop = DateTime.MinValue;
foreach (var key in keys)
{
var start = starts[key];
var stop = stops[key];
start.ShouldBeGreaterThanOrEqualTo(lastStop);
stop.ShouldBeGreaterThan(start);
lastStop = stop;
}
}