Creating the AsyncLock

Now that we have built the AsyncSemaphore class, we will use this object inside the AsyncLock object. Let's add a new file called AsyncLock.cs into the Threading folder and implement the following:

public class AsyncLock
    {
        private readonly AsyncSemaphore m_semaphore;
        private readonly Task<Releaser> m_releaser;
        public AsyncLock()
          {
              m_semaphore = new AsyncSemaphore(1);
              m_releaser = Task.FromResult(new Releaser(this));
          }
        public Task<Releaser> LockAsync()
         {
              var wait = m_semaphore.WaitAsync();
              return wait.IsCompleted ?
              m_releaser :
              wait.ContinueWith((_, state) =>
              new Releaser((AsyncLock)state),
                this, CancellationToken.None,
                TaskContinuationOptions.ExecuteSynchronously, TaskScheduler.Default);
     }
       public struct Releaser : IDisposable
         {
    ...