/// <summary>
/// Subscribes a delegate to an event.
/// </summary>
/// <param name="action">The delegate that gets executed when the event is published.</param>
/// <param name="threadOption">Specifies on which thread to receive the delegate callback.</param>
/// <param name="keepSubscriberReferenceAlive">When <see langword="true"/>, the <see cref="PubSubEvent"/> keeps a reference to the subscriber so it does not get garbage collected.</param>
/// <returns>A <see cref="SubscriptionToken"/> that uniquely identifies the added subscription.</returns>
/// <remarks>
/// If <paramref name="keepSubscriberReferenceAlive"/> is set to <see langword="false" />, <see cref="PubSubEvent"/> will maintain a <see cref="WeakReference"/> to the Target of the supplied <paramref name="action"/> delegate.
/// If not using a WeakReference (<paramref name="keepSubscriberReferenceAlive"/> is <see langword="true" />), the user must explicitly call Unsubscribe for the event when disposing the subscriber in order to avoid memory leaks or unexpected behavior.
/// <para/>
/// The PubSubEvent collection is thread-safe.
/// </remarks>
public SubscriptionToken Subscribe(Action action, ThreadOption threadOption, bool keepSubscriberReferenceAlive)
{
IDelegateReference actionReference = new DelegateReference(action, keepSubscriberReferenceAlive);
EventSubscription subscription;
switch (threadOption)
{
case ThreadOption.PublisherThread:
subscription = new EventSubscription(actionReference);
break;
case ThreadOption.BackgroundThread:
subscription = new BackgroundEventSubscription(actionReference);
break;
case ThreadOption.UIThread:
if (SynchronizationContext == null) throw new InvalidOperationException(Resources.EventAggregatorNotConstructedOnUIThread);
subscription = new DispatcherEventSubscription(actionReference, SynchronizationContext);
break;
default:
subscription = new EventSubscription(actionReference);
break;
}
return base.InternalSubscribe(subscription);
}
/// <summary>
/// Subscribes a delegate to an event.
/// </summary>
/// <param name="action">The delegate that gets executed when the event is published.</param>
/// <param name="threadOption">Specifies on which thread to receive the delegate callback.</param>
/// <param name="keepSubscriberReferenceAlive">When <see langword="true"/>, the <see cref="PubSubEvent"/> keeps a reference to the subscriber so it does not get garbage collected.</param>
/// <returns>A <see cref="SubscriptionToken"/> that uniquely identifies the added subscription.</returns>
/// <remarks>
/// If <paramref name="keepSubscriberReferenceAlive"/> is set to <see langword="false" />, <see cref="PubSubEvent"/> will maintain a <see cref="WeakReference"/> to the Target of the supplied <paramref name="action"/> delegate.
/// If not using a WeakReference (<paramref name="keepSubscriberReferenceAlive"/> is <see langword="true" />), the user must explicitly call Unsubscribe for the event when disposing the subscriber in order to avoid memory leaks or unexpected behavior.
/// <para/>
/// The PubSubEvent collection is thread-safe.
/// </remarks>
public virtual SubscriptionToken Subscribe(Action action, ThreadOption threadOption, bool keepSubscriberReferenceAlive)
{
IDelegateReference actionReference = new DelegateReference(action, keepSubscriberReferenceAlive);
EventSubscription subscription;
switch (threadOption)
{
case ThreadOption.PublisherThread:
subscription = new EventSubscription(actionReference);
break;
case ThreadOption.BackgroundThread:
subscription = new BackgroundEventSubscription(actionReference);
break;
case ThreadOption.UIThread:
if (SynchronizationContext == null)
{
throw new InvalidOperationException(Resources.EventAggregatorNotConstructedOnUIThread);
}
subscription = new DispatcherEventSubscription(actionReference, SynchronizationContext);
break;
default:
subscription = new EventSubscription(actionReference);
break;
}
return(InternalSubscribe(subscription));
}
public void KeepAlivePreventsDelegateFromBeingCollected()
{
var delegates = new SomeClassHandler();
var delegateReference = new DelegateReference((Action<string>)delegates.DoEvent, true);
delegates = null;
GC.Collect();
Assert.NotNull(delegateReference.Target);
}
public void TargetShouldReturnAction()
{
var classHandler = new SomeClassHandler();
Action<string> myAction = new Action<string>(classHandler.MyAction);
var weakAction = new DelegateReference(myAction, false);
((Action<string>)weakAction.Target)("payload");
Assert.Equal("payload", classHandler.MyActionArg);
}
public void NotKeepAliveAllowsDelegateToBeCollected()
{
var delegates = new SomeClassHandler();
var delegateReference = new DelegateReference((Action<string>)delegates.DoEvent, false);
delegates = null;
GC.Collect();
Assert.Null(delegateReference.Target);
}
public void ShouldReturnNullIfTargetNotAlive()
{
SomeClassHandler handler = new SomeClassHandler();
var weakHandlerRef = new WeakReference(handler);
var action = new DelegateReference((Action<string>)handler.DoEvent, false);
handler = null;
GC.Collect();
Assert.False(weakHandlerRef.IsAlive);
Assert.Null(action.Target);
}
public void ShouldAllowCollectionOfOriginalDelegate()
{
var classHandler = new SomeClassHandler();
Action<string> myAction = new Action<string>(classHandler.MyAction);
var weakAction = new DelegateReference(myAction, false);
var originalAction = new WeakReference(myAction);
myAction = null;
GC.Collect();
Assert.False(originalAction.IsAlive);
((Action<string>)weakAction.Target)("payload");
Assert.Equal("payload", classHandler.MyActionArg);
}
public void NotKeepAliveKeepsDelegateIfStillAlive()
{
var delegates = new SomeClassHandler();
var delegateReference = new DelegateReference((Action<string>)delegates.DoEvent, false);
GC.Collect();
Assert.NotNull(delegateReference.Target);
GC.KeepAlive(delegates); //Makes delegates ineligible for garbage collection until this point (to prevent oompiler optimizations that may release the referenced object prematurely).
delegates = null;
GC.Collect();
Assert.Null(delegateReference.Target);
}
/// <summary>
/// Subscribes a delegate to an event.
/// </summary>
/// <param name="action">The delegate that gets executed when the event is published.</param>
/// <param name="threadOption">Specifies on which thread to receive the delegate callback.</param>
/// <param name="keepSubscriberReferenceAlive">When <see langword="true"/>, the <see cref="PubSubEvent{TPayload}"/> keeps a reference to the subscriber so it does not get garbage collected.</param>
/// <param name="filter">Filter to evaluate if the subscriber should receive the event.</param>
/// <returns>A <see cref="SubscriptionToken"/> that uniquely identifies the added subscription.</returns>
/// <remarks>
/// If <paramref name="keepSubscriberReferenceAlive"/> is set to <see langword="false" />, <see cref="PubSubEvent{TPayload}"/> will maintain a <see cref="WeakReference"/> to the Target of the supplied <paramref name="action"/> delegate.
/// If not using a WeakReference (<paramref name="keepSubscriberReferenceAlive"/> is <see langword="true" />), the user must explicitly call Unsubscribe for the event when disposing the subscriber in order to avoid memory leaks or unexpected behavior.
///
/// The PubSubEvent collection is thread-safe.
/// </remarks>
public virtual SubscriptionToken Subscribe(Action <TPayload> action, ThreadOption threadOption, bool keepSubscriberReferenceAlive, Predicate <TPayload> filter)
{
IDelegateReference actionReference = new DelegateReference(action, keepSubscriberReferenceAlive);
IDelegateReference filterReference;
if (filter != null)
{
filterReference = new DelegateReference(filter, keepSubscriberReferenceAlive);
}
else
{
filterReference = new DelegateReference(new Predicate <TPayload>(delegate { return(true); }), true);
}
EventSubscription <TPayload> subscription;
switch (threadOption)
{
case ThreadOption.PublisherThread:
subscription = new EventSubscription <TPayload>(actionReference, filterReference);
break;
case ThreadOption.BackgroundThread:
subscription = new BackgroundEventSubscription <TPayload>(actionReference, filterReference);
break;
case ThreadOption.UIThread:
if (SynchronizationContext == null)
{
throw new InvalidOperationException(Resources.EventAggregatorNotConstructedOnUIThread);
}
subscription = new DispatcherEventSubscription <TPayload>(actionReference, filterReference, SynchronizationContext);
break;
default:
subscription = new EventSubscription <TPayload>(actionReference, filterReference);
break;
}
return(base.InternalSubscribe(subscription));
}
public void WeakDelegateWorksWithStaticMethodDelegates()
{
var action = new DelegateReference((Action)SomeClassHandler.StaticMethod, false);
Assert.NotNull(action.Target);
}
