这是从here获取的IEventProcessor实现的一部分:
CFDictionaryRemoveValue(keychainQuery, kSecReturnData);
CFDictionaryRemoveValue(keychainQuery, kSecMatchLimit);
当新事件添加到EventHub时,将调用ProcessEventsAsync方法,并且可以使用foreach循环来处理事件。我现在想要将Observers添加到SimpleEventProcessor中,例如使用ObserverRegistry,如所讨论的here。建议的ObserverRegistry看起来像这样:
public class SimpleEventProcessor : IEventProcessor
{
public async Task ProcessEventsAsync(PartitionContext context, IEnumerable<EventData> events)
{
foreach (EventData eventData in events)
{
}
}
}
不幸的是,遗漏了一些东西。如何在SimpleEventProcessor中注册多个观察者,以便将事件从ProcessEventsAsync传递给所有观察者,最终传递给他们的When方法?
答案 0 :(得分:2)
完整源代码为here。概要如下:
您可以在SimpleEventProcessor上定义静态事件:
public class SimpleEventProcessor : IEventProcessor
{
public static event EventHandler<MessageReceivedEventArgs> OnMessageReceived;
public SimpleEventProcessor()
{ }
}
然后在ProcessEventsAsync中引发OnMessageReceived事件:
public Task ProcessEventsAsync(PartitionContext context, IEnumerable<EventData> messages)
{
foreach (EventData message in messages)
{
OnMessageReceived(this, new MessageReceivedEventArgs() { ReceivedOn = DateTimeOffset.UtcNow, Message = message });
}
}
非常重要:确保在处理器关闭时删除所有订阅者。这非常重要,因为缺少取消订阅的静态事件可能导致内存泄漏article explaining this。:
public async Task CloseAsync(PartitionContext context, CloseReason reason)
{
if (OnMessageReceived != null)
{
foreach (EventHandler<MessageReceivedEventArgs> subscriber in OnMessageReceived.GetInvocationList())
{
OnMessageReceived -= subscriber;
}
}
}
最后,您可以将观察者作为初始化逻辑的一部分进行连接:
ObserverRegistry registry = new ObserverRegistry();
foreach (IObserver observer in registry.GetObservers())
{
SimpleEventProcessor.OnMessageReceived += new EventHandler<MessageReceivedEventArgs>(
(sender, e) => observer.When(e));
}
控制台应用程序的示例输出:
SimpleEventProcessor: bc84f0b9-6e2d-4c4e-9169-c1bd277d3c18
Observer1: bc84f0b9-6e2d-4c4e-9169-c1bd277d3c18
Observer2: bc84f0b9-6e2d-4c4e-9169-c1bd277d3c18
SimpleEventProcessor: a29d5875-7c53-4a7c-8113-ef7c24c2851f
Observer1: a29d5875-7c53-4a7c-8113-ef7c24c2851f
Observer2: a29d5875-7c53-4a7c-8113-ef7c24c2851f
我想强调以下内容:
IEventProcessorFactory
可能会更有效,因为您可以更好地控制处理器实例化和处理。希望以上回答你的问题。