Is this thread-safe?
The EventAggregator in Prism is a very simple class with only one method. I was surprised when I noticed that there was no lock around the null check and creation of a new type to add to the private _events collection. If two threads called GetEvent simultaneously for the same type (before it exists in _events) it looks like this would result in two entries in the collection.
/// <summary>
/// Gets the single instance of the event managed by this EventAggregator. Multiple calls to this method with the same <typeparamref name="TEventType"/> returns the same event instance.
/// </summary>
/// <typeparam name="TEventType">The type of event to get. This must inherit from <see cref="EventBase"/>.</typeparam>
/// <returns>A singleton instance of an event object of type <typeparamref name="TEventType"/>.</returns>
public TEventType GetEvent<TEventType>() where TEventType : EventBase
{
TEventType eventInstance = _events.FirstOrDefault(evt => evt.GetType() == typeof(TEventType)) as TEventType;
if (eventInstance == null)
{
eventInstance = Activator.CreateInstance<TEventType>();
_events.Add(eventInstance);
}
return eventInstance;
}
An Event Aggregator acts as a single source of events for many objects. It registers for all the events of the many objects allowing clients to register with just the aggregator.
What is Prism EventAggregator? In short, EventAggregator is Prism's implementation of the Publisher-Subscriber pattern. Publisher-Subscriber is a messaging pattern designed to facilitate asynchronous communication in your application.
The Prism Library provides an event mechanism that enables communications between loosely coupled components in the application. This mechanism, based on the event aggregator service, allows publishers and subscribers to communicate through events and still do not have a direct reference to each other.
No, not thread safe.
I would
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