We are using the NoTrackingReleasePolicy on the Windsor container due to the memory leaks that occur when we do not Release our components after usage. Now consider the following problem.
Some disposable component:
public class DisposableComponent : IDisposable
{
private bool _disposed;
public bool Disposed
{
get { return _disposed; }
}
public void Dispose()
{
_disposed = true;
GC.SuppressFinalize(this);
}
}
Some class using the disposable component:
public class ClassWithReferenceToDisposableService
{
private DisposableComponent _disposableComponent;
public ClassWithReferenceToDisposableService(DisposableComponent disposableComponent)
{
_disposableComponent = disposableComponent;
}
}
And finaly a test which configures these components as transient and resolve/release them:
[Test]
public void ReleaseComponent_ServiceWithReferenceToTransientDisposable_TransientComponentDisposed()
{
// arrange
var windsorContainer = new WindsorContainer();
windsorContainer.Kernel.ReleasePolicy = new NoTrackingReleasePolicy();
windsorContainer.Register(Component.For<ClassWithReferenceToDisposableService>().LifeStyle.Transient);
windsorContainer.Register(Component.For<DisposableComponent>().LifeStyle.Transient);
ClassWithReferenceToDisposableService service =
windsorContainer.Resolve<ClassWithReferenceToDisposableService>();
// act
windsorContainer.Release(service);
}
Now, if I remove the NoTrackingReleasePolicy, Windsor will dispose the transient service as expected, but I can not do this (period). Now, what I want to achieve is that Windsor disposes the transient components (anywhere in the resolve graph) when I invoke ReleaseCompnent. Is there any way to achieve this without changing the NoTrackingReleasePolicy?
No, you can't have your cake and eat it too.
You can implement your own custom policy that is kind of like NoTrackingReleasePolicy but will track some components...
Related
I am trying to use MvvmCross v3 in one of my applications which consists of activities, content providers and broadcast receivers. However, I am not quite succeeding.
The application consists of a Core PCL which contains logic, models and viewmodels and a Droid application which contains all MonoDroid-specific stuff.
In Core I have an App:MvxApplication class and in Droid I have a Setup:MvxSetup class which creates an App-instance and initialises stuff.
I can use the IOC parts with content providers, broadcast receivers and non-Mvx-activities without problems. When I now want to add an MvxActivity it falls apart.
When the Mvx Activity launches I get an exception "Cirrious.CrossCore.Exceptions.MvxException: MvxTrace already initialized".
Obviously I am initialising things in the wrong order / wrong place. But, I need a pointer in the right direction.
My App Class
public class App
: MvxApplication
{
public override void Initialize()
{
base.Initialize();
InitialisePlugins();
InitaliseServices();
InitialiseStartNavigation();
}
private void InitaliseServices()
{
CreatableTypes().EndingWith("Service").AsInterfaces().RegisterAsLazySingleton();
}
private void InitialiseStartNavigation()
{
}
private void InitialisePlugins()
{
// initialise any plugins where are required at app startup
// e.g. Cirrious.MvvmCross.Plugins.Visibility.PluginLoader.Instance.EnsureLoaded();
}
}
And my setup class
public class Setup
: MvxAndroidSetup
{
public Setup(Context applicationContext)
: base(applicationContext)
{
}
protected override IMvxApplication CreateApp()
{
return new App();
}
protected override IMvxNavigationSerializer CreateNavigationSerializer()
{
return new MvxJsonNavigationSerializer();
}
public override void LoadPlugins(Cirrious.CrossCore.Plugins.IMvxPluginManager pluginManager)
{
pluginManager.EnsurePluginLoaded<Cirrious.MvvmCross.Plugins.Json.PluginLoader>();
base.LoadPlugins(pluginManager);
}
public void RegisterServices()
{
// I register a bunch of singletons here
}
// The following is called from my content provider's OnCreate()
// Which is the first code that is run
public static void DoSetup(Context applicationContext)
{
var setup = new Setup(applicationContext);
setup.Initialize();
setup.RegisterServices();
}
My Content provider's OnCreate():
public override bool OnCreate()
{
Log.Debug(Tag, "OnCreate");
_context = Context;
Setup.DoSetup(_context);
return true;
}
My MvxActivity:
[Activity(Label = "#string/ApplicationName", MainLauncher = true)]
[IntentFilter(new[] { "Settings" })]
public class SettingsView
: MvxActivity
{
public new SettingsViewModel ViewModel
{
get { return (SettingsViewModel) base.ViewModel; }
set { base.ViewModel = value; }
}
protected override void OnViewModelSet()
{
SetContentView(Resource.Layout.Page_SettingsView);
}
}
Short answer (I'm in an airport on mobile)
all the mvx android views will check the setup singleton has been created - https://github.com/slodge/MvvmCross/blob/vnext/Cirrious/Cirrious.MvvmCross.Droid/Platform/MvxAndroidSetupSingleton.cs (vnext tree - but similar on v3)
so if you are creating a setup, but not setting this singleton, then you will get a second setup created when you first show a view
i suspect you can just get your setup created via the singleton class, but if this isn't flexible enough for your needs, then please log an issue on github
would also love to see some blogging about this - I've not used custom content providers much (at all!)
Hi have the following component registered into Castle Windsor:
public class CommandDispatcher : IServiceCommandDispatcher
{
private readonly IWindsorContainer container;
public CommandDispatcher(IWindsorContainer container)
{
this.container = container;
}
#region IServiceCommandDispatcher Members
public void Dispatch<TCommand>(TCommand command) where TCommand : IServiceCommand
{
var handler = container.Resolve<IServiceCommandHandler<TCommand>>();
handler.Handle(command);
}
#endregion
}
And the dispatcher is registered in the following way:
Component
.For<IServiceCommandDispatcher>()
.ImplementedBy<CommandDispatcher>(),
But the field container is null when I resolve an instance of the dispatcher.
What should I do in order to pass the container to the resolved children items?
Windsor solves this problem for you with the Typed Factory Facility.
In the below example I want the implementation of ICommandHandlerFactory to resolve my command handler from my windsor container.
class CommandDispatcher : IServiceCommandDispatcher
{
private readonly ICommandHandlerFactory factory;
public CommandDispatcher(ICommandHandlerFactory factory)
{
this.factory = factory;
}
public void Dispatch<T>(T command) where T : IServiceCommand
{
var handler = this.factory.Create(command);
handler.Handle(command);
this.factory.Destroy(handler);
}
}
To achieve this I only need to create the ICommandHandlerFactory Interface.
public interface ICommandHandlerFactory
{
Handles<T> Create<T>(T command) where T : IServiceCommand;
void Destroy(object handler);
}
No implementation of ICommandHandlerFactory is required as Windsor will create the implementation. Windsor uses the convention that a method that returns an object is a resolve method and a method that returns void is a release method.
To register the factory you need to include using Castle.Facilities.TypedFactory and then register your factory as follows
container.AddFacility<TypedFactoryFacility>();
container.Register(
Component.For<ICommandHandlerFactory>()
.AsFactory()
);
Just to reiterate you do not have to write any implementation code for your factory.
This works:
container.Register(Component.For<IWindsorContainer>().Instance(container));
It's not ideal, because you still have to call the Resolve method. There may be a better way to do this, using a factory. This looks similar to what you're trying to do:
http://kozmic.net/2010/03/11/advanced-castle-windsor-ndash-generic-typed-factories-auto-release-and-more/
I have an MVVM Cross application running on Windows Phone 8 which I recently ported across to using Portable Class Libraries.
The view models are within the portable class library and one of them exposes a property which enables and disables a PerformanceProgressBar from the Silverlight for WP toolkit through data binding.
When the user presses a button a RelayCommand kicks off a background process which sets the property to true which should enable the progress bar and does the background processing.
Before I ported it to a PCL I was able to invoke the change from the UI thread to ensure the progress bar got enabled, but the Dispatcher object isn't available in a PCL. How can I work around this?
Thanks
Dan
All the MvvmCross platforms require that UI-actions get marshalled back on to the UI Thread/Apartment - but each platform does this differently....
To work around this, MvvmCross provides a cross-platform way to do this - using an IMvxViewDispatcherProvider injected object.
For example, on WindowsPhone IMvxViewDispatcherProvider is provided ultimately by MvxMainThreadDispatcher in https://github.com/slodge/MvvmCross/blob/vnext/Cirrious/Cirrious.MvvmCross.WindowsPhone/Views/MvxMainThreadDispatcher.cs
This implements the InvokeOnMainThread using:
private bool InvokeOrBeginInvoke(Action action)
{
if (_uiDispatcher.CheckAccess())
action();
else
_uiDispatcher.BeginInvoke(action);
return true;
}
For code in ViewModels:
your ViewModel inherits from MvxViewModel
the MvxViewModel inherits from an MvxApplicationObject
the MvxApplicationObject inherits from an MvxNotifyPropertyChanged
the MvxNotifyPropertyChanged object inherits from an MvxMainThreadDispatchingObject
MvxMainThreadDispatchingObject is https://github.com/slodge/MvvmCross/blob/vnext/Cirrious/Cirrious.MvvmCross/ViewModels/MvxMainThreadDispatchingObject.cs
public abstract class MvxMainThreadDispatchingObject
: IMvxServiceConsumer<IMvxViewDispatcherProvider>
{
protected IMvxViewDispatcher ViewDispatcher
{
get { return this.GetService().Dispatcher; }
}
protected void InvokeOnMainThread(Action action)
{
if (ViewDispatcher != null)
ViewDispatcher.RequestMainThreadAction(action);
}
}
So... your ViewModel can just call InvokeOnMainThread(() => DoStuff());
One further point to note is that MvvmCross automatically does UI thread conversions for property updates which are signalled in a MvxViewModel (or indeed in any MvxNotifyPropertyChanged object) through the RaisePropertyChanged() methods - see:
protected void RaisePropertyChanged(string whichProperty)
{
// check for subscription before going multithreaded
if (PropertyChanged == null)
return;
InvokeOnMainThread(
() =>
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(whichProperty));
});
}
in https://github.com/slodge/MvvmCross/blob/vnext/Cirrious/Cirrious.MvvmCross/ViewModels/MvxNotifyPropertyChanged.cs
This automatic marshalling of RaisePropertyChanged() calls works well for most situations, but can be a bit inefficient if you Raise a lot of changed properties from a background thread - it can lead to a lot of thread context switching. It's not something you need to be aware of in most of your code - but if you ever do find it is a problem, then it can help to change code like:
MyProperty1 = newValue1;
MyProperty2 = newValue2;
// ...
MyProperty10 = newValue10;
to:
InvokeOnMainThread(() => {
MyProperty1 = newValue1;
MyProperty2 = newValue2;
// ...
MyProperty10 = newValue10;
});
If you ever use ObservableCollection, then please note that MvvmCross does not do any thread marshalling for the INotifyPropertyChanged or INotifyCollectionChanged events fired by these classes - so it's up to you as a developer to marshall these changes.
The reason: ObservableCollection exists in the MS and Mono code bases - so there is no easy way that MvvmCross can change these existing implementations.
If you don't have access to the Dispatcher, you can just pass a delegate of the BeginInvoke method to your class:
public class YourViewModel
{
public YourViewModel(Action<Action> beginInvoke)
{
this.BeginInvoke = beginInvoke;
}
protected Action<Action> BeginInvoke { get; private set; }
private void SomeMethod()
{
this.BeginInvoke(() => DoSomething());
}
}
Then to instanciate it (from a class that has access to the dispatcher):
var dispatcherDelegate = action => Dispatcher.BeginInvoke(action);
var viewModel = new YourViewModel(dispatcherDelegate);
Or you can also create a wrapper around your dispatcher.
First, define a IDispatcher interface in your portable class library:
public interface IDispatcher
{
void BeginInvoke(Action action);
}
Then, in the project who has access to the dispatcher, implement the interface:
public class DispatcherWrapper : IDispatcher
{
public DispatcherWrapper(Dispatcher dispatcher)
{
this.Dispatcher = dispatcher;
}
protected Dispatcher Dispatcher { get; private set; }
public void BeginInvoke(Action action)
{
this.Dispatcher.BeginInvoke(action);
}
}
Then you can just pass this object as a IDispatcher instance to your portable class library.
Another option that could be easier is to store a reference to SynchronizationContext.Current in your class's constructor. Then, later on, you can use _context.Post(() => ...) to invoke on the context -- which is the UI thread in WPF/WinRT/SL.
class MyViewModel
{
private readonly SynchronizationContext _context;
public MyViewModel()
{
_context = SynchronizationContext.Current.
}
private void MyCallbackOnAnotherThread()
{
_context.Post(() => UpdateTheUi());
}
}
In MEF it's possible to set the dependencies for an existing object using something like:
container.SatisfyImportsOnce(instance);
Is it possible to do the same with Castle Windsor?
I'm using (read: learning) Caliburn.Micro, and trying to update the template project from MEF to Windsor, which is where I've come across the issue.
Sorry Neil, Windsor doesn't have that feature
Castle Windsor FAQ
Windsor will resolve a property dependency (which it considers an optional dependency) such as an ILogger property if there is a registered component for that service. But this only happens during component activation...when the component is constructed the first time, there is no way to pass Windsor an existing instance and inject components into properties.
With Castle Windsor you can register an existing instance with the container, is this the kind of thing you are looking for?
var instance = new Logger();
var container = new WindsorContainer();
container.Register(Component.For<ILogger>().Instance(instance))
where
public interface ILogger
{
void LogException(Exception ex);
}
public class Logger : ILogger
{
public void LogException(Exception ex)
{
// Log exception
}
}
You can however code this functionality yourself. For example, here is an ASP.NET MVC FilterAttributeFilterProvider, used to inject proprties onto attribute action filters.
public class AttributeFilterProvider : FilterAttributeFilterProvider
{
public AttributeFilterProvider(IKernel kernel)
{
_kernel = kernel;
}
private readonly IKernel _kernel;
protected override IEnumerable<FilterAttribute> GetControllerAttributes(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
{
var attributes = base.GetControllerAttributes(controllerContext, actionDescriptor);
BuildUpAttributeDependancies(attributes);
return attributes;
}
protected override IEnumerable<FilterAttribute> GetActionAttributes(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
{
var attributes = base.GetActionAttributes(controllerContext, actionDescriptor);
BuildUpAttributeDependancies(attributes);
return attributes;
}
private void BuildUpAttributeDependancies(IEnumerable<FilterAttribute> attributes)
{
foreach (var attribute in attributes)
{
var propInfos = attribute.GetType().GetProperties().Where(x => x.GetValue(attribute) == null).AsEnumerable();
foreach (var pi in propInfos)
{
if (_kernel.HasComponent(pi.PropertyType))
{
var service = _kernel.Resolve(pi.PropertyType);
pi.SetValue(attribute, service);
}
}
}
}
}
In the BuildUpAttributeDependancies method, we look for un-initialised (null) properties, and then check to see if the type has been registered with Castle Windsor. If it has, we set the property.
By replacing the default FilterAttributeFilterProvider with our custom one (above) in the global.asax file we can now use Castle Windsors DI features to inject any type onto any Action Filter in our MVC application. To complete this answer fully, here is an example of a global.asax application class with Castle Windsor setup for both Controller (at instantiation time) and ActionFilter (at usage time) dependancy injection:
public class MvcApplication : System.Web.HttpApplication
{
private static IWindsorContainer _container;
private static void BootstrapContainer()
{
_container = new WindsorContainer()
.Install(FromAssembly.This());
var controllerFactory = new ControllerFactory(_container.Kernel);
ControllerBuilder.Current.SetControllerFactory(controllerFactory);
}
private static void BootstrapFilters()
{
var oldProvider = FilterProviders.Providers.Single(f => f is FilterAttributeFilterProvider);
FilterProviders.Providers.Remove(oldProvider);
var provider = new AttributeFilterProvider(_container.Kernel);
FilterProviders.Providers.Add(provider);
}
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
BootstrapContainer();
BootstrapFilters();
}
}
Consider the following example:
public interface ITask
{
void Execute();
}
public class LoggingTaskRunner : ITask
{
private readonly ITask _taskToDecorate;
private readonly MessageBuffer _messageBuffer;
public LoggingTaskRunner(ITask taskToDecorate, MessageBuffer messageBuffer)
{
_taskToDecorate = taskToDecorate;
_messageBuffer = messageBuffer;
}
public void Execute()
{
_taskToDecorate.Execute();
Log(_messageBuffer);
}
private void Log(MessageBuffer messageBuffer)
{}
}
public class TaskRunner : ITask
{
public TaskRunner(MessageBuffer messageBuffer)
{
}
public void Execute()
{
}
}
public class MessageBuffer
{
}
public class Configuration
{
public void Configure()
{
IWindsorContainer container = null;
container.Register(
Component.For<MessageBuffer>()
.LifeStyle.Transient);
container.Register(
Component.For<ITask>()
.ImplementedBy<LoggingTaskRunner>()
.ServiceOverrides(ServiceOverride.ForKey("taskToDecorate").Eq("task.to.decorate")));
container.Register(
Component.For<ITask>()
.ImplementedBy<TaskRunner>()
.Named("task.to.decorate"));
}
}
How can I make Windsor instantiate the "shared" transient component so that both "Decorator" and "Decorated" gets the same instance?
Edit: since the design is being critiqued I am posting something closer to what is being done in the app. Maybe someone can suggest a better solution (if sharing the transient resource between a logger and the true task is considered a bad design)
Edit2: Castle3 has added support for this (http://docs.castleproject.org/Windsor.Whats-New-In-Windsor-3.ashx) by introducing the "Bound" lifestyle
'Transient' explicitly means 'non-shared', so what you are asking is conceptually the wrong thing to do. The correct solution is to register Shared as a Singleton instead of Transient:
container.Register(Component.For<Shared>());
(Singleton is the default lifetime in Windsor.)
However, I suspect that behind the stated question lies a much more complex problem. I'm guessing that you need Shared to be Transient because you need it with this lifestyle for a lot of other cases, but exactly when it comes to the relationship between Decorator and Decorated you need to share them.
I still think this sounds like a Design Smell, but there are at least two ways you can achieve this result.
The first option involves prematurely resolving Shared and explicitly supply the resolved instance to the configuration of the two IFoo registrations:
container.Register(Component.For<Shared>().LifeStyle.Transient);
var r = container.Resolve<Shared>();
container.Register(Component
.For<IFoo>()
.ImplementedBy<Decorator>()
.DependsOn(new { resource = r }));
container.Register(Component
.For<IFoo>()
.ImplementedBy<Decorated>()
.DependsOn(new { resource = r }));
The second option is to make a specialized, named registration for Shared that is used only by the IFoo registrations:
container.Register(Component.For<Shared>().LifeStyle.Transient);
container.Register(Component.For<Shared>().Named("shared"));
container.Register(Component
.For<IFoo>()
.ImplementedBy<Decorator>()
.ServiceOverrides(new { resource = "shared" }));
container.Register(Component
.For<IFoo>()
.ImplementedBy<Decorated>()
.ServiceOverrides(new { resource = "shared" }));