/// <summary>
/// Creates the <see cref="IHttpController"/> specified by <paramref name="controllerType"/> using the given <paramref name="request"/>
/// </summary>
/// <param name="request">The request message.</param>
/// <param name="controllerType">Type of the controller.</param>
/// <param name="controllerDescriptor">The controller descriptor</param>
/// <returns>An instance of type <paramref name="controllerType"/>.</returns>
public IHttpController Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
{
if (request == null)
{
throw Error.ArgumentNull("request");
}
if (controllerDescriptor == null)
{
throw Error.ArgumentNull("controllerDescriptor");
}
if (controllerType == null)
{
throw Error.ArgumentNull("controllerType");
}
try
{
// First check in the local fast cache and if not a match then look in the broader
// HttpControllerDescriptor.Properties cache
if (_fastCache == null)
{
// If dependency resolver returns controller object then keep asking it whenever we need a new instance
IHttpController instance = (IHttpController)request.GetDependencyScope().GetService(controllerType);
if (instance != null)
{
return(instance);
}
// Otherwise create a delegate for creating a new instance of the type
Func <IHttpController> activator = TypeActivator.Create <IHttpController>(controllerType);
Tuple <HttpControllerDescriptor, Func <IHttpController> > cacheItem = Tuple.Create(controllerDescriptor, activator);
Interlocked.CompareExchange(ref _fastCache, cacheItem, null);
// Execute the delegate
return(activator());
}
else if (_fastCache.Item1 == controllerDescriptor)
{
// If the key matches and we already have the delegate for creating an instance then just execute it
return(_fastCache.Item2());
}
else
{
// If the key doesn't match then lookup/create delegate in the HttpControllerDescriptor.Properties for
// that HttpControllerDescriptor instance
Func <IHttpController> activator = (Func <IHttpController>)controllerDescriptor.Properties.GetOrAdd(
_cacheKey,
key => TypeActivator.Create <IHttpController>(controllerType));
return(activator());
}
}
catch (Exception ex)
{
throw Error.InvalidOperation(ex, SRResources.DefaultControllerFactory_ErrorCreatingController, controllerType.Name);
}
}
// Returns the controller instance from the dependency resolver if there is one registered
// else returns the activator that calls the default ctor for the give controllerType.
private static IHttpController GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, out Func <IHttpController> activator)
{
Contract.Assert(request != null);
Contract.Assert(controllerType != null);
// If dependency resolver returns controller object then use it.
IHttpController instance = (IHttpController)request.GetDependencyScope().GetService(controllerType);
if (instance != null)
{
activator = null;
return(instance);
}
// Otherwise create a delegate for creating a new instance of the type
activator = TypeActivator.Create <IHttpController>(controllerType);
return(null);
}
