An implementation of a TaskScheduler running code on a thread designated by an Android.OS.Handler (MonoDroid)

AndroidTaskScheduler.cs

namespace BlackFox
{
    using System;
    using System.Collections.Generic;
    using System.Threading.Tasks;
    using Android.OS;

    /// <summary>
    /// Provides a <see cref="TaskScheduler"/> using an android <see cref="Handler"/> to run the tasks.
    /// </summary>
    public class AndroidTaskScheduler : TaskScheduler
    {
        readonly Handler handler;

        /// <summary>Initializes a new instance of the AndroidTaskScheduler class.</summary>
        /// <remarks>This constructors defaults to using the android handler associated with the current thread.</remarks>
        public AndroidTaskScheduler()
        {
            handler = new Handler();
        }

        /// <summary>Initializes a new instance of the AndroidTaskScheduler class.</summary>
        /// <param name="handler">The android Handler that will be used to run the tasks.</param>
        public AndroidTaskScheduler(Handler handler)
        {
            if (handler == null) throw new ArgumentNullException("handler");

            this.handler = handler;
        }

        protected override IEnumerable<Task> GetScheduledTasks()
        {
            // A class derived from TaskScheduler implements this method in order to support integration with
            // debuggers. We don't support such integration ;-)
            throw new NotSupportedException();
        }

        protected override void QueueTask(Task task)
        {
            handler.Post(() => TryExecuteTask(task));
        }

        protected override bool TryExecuteTaskInline(Task task, bool taskWasPreviouslyQueued)
        {
            var currentLooper = Looper.MyLooper();
            if (currentLooper == null || !currentLooper.Equals(handler.Looper)) return false;
            if (taskWasPreviouslyQueued) return false;

            return TryExecuteTask(task);
        }

        public override int MaximumConcurrencyLevel
        {
            get
            {
                return 1;
            }
        }
    }
}