BackgroundFactoryMethod

gistfile1.cs

/// <summary>
/// Register the component in a background thread on the thread pool.
/// Exceptions from factory method are thrown when the component is resolved.
/// </summary>
/// <typeparam name="TService">Type of service your component IS or IMPLEMENTS.</typeparam>
/// <param name="serviceRegistration">Previous registration that is not committed to method of instantiation of component.</param>
/// <param name="factory">The actual factory method for creating the service</param>
/// <param name="beforeInitialization">An optional callback that is run on the thread pool thread before initialization happens. 
/// You can use this let the thread pool thread block and wait on e.g. a synchronization primitive.</param>
/// <returns>A component registration for Windsor which contains everything Windsor needs to know to use
/// your factory method to create the component</returns>
public static ComponentRegistration<TService> UsingBackgroundFactoryMethod<TService>(
	this ComponentRegistration<TService> serviceRegistration,
	Func<TService> factory,
	Action beforeInitialization = null)
	where TService : class
{
	var waitForComp = new ManualResetEventSlim(false);
			
	TService createdComponent = null;
	Exception thrownException = null;

	ThreadPool.QueueUserWorkItem(_ =>
		{
			_logger.Debug("thread pool before initialization executing");
			if (beforeInitialization != null) beforeInitialization();
			_logger.Debug("thread pool factory starting");
			try
			{
				createdComponent = factory();
				_logger.Debug("thread pool factory done");
			}
			catch (Exception e)
			{
				_logger.Error("thread pool initialization exception", e);
				thrownException = e;
			}
			waitForComp.Set();
		});

	var bus = new Lazy<TService>(() =>
		{
			_logger.Debug("waiting for initialization");
			waitForComp.Wait();
			if (thrownException != null) throw thrownException;
			_logger.Debug("yielding created component");
			return createdComponent;
		});

	return serviceRegistration.UsingFactoryMethod(() => bus.Value);
}