SignalHubT

Single-threaded EventAggregator/EventBroker C# solution

How it works

SignalBus<T> stores collection of ISubscriptions to specific ISignalData type.

SignalHub stores collection of SignalBus<T> and provides interface to send ISignalData through sequence of ISubscriptions.

Features

• Global and Filtered subscription

  • Publish message without filter triggers only Global subscriptions
  • Publish message with Filter triggers Global and Filtered subscriptions
    • Global and Filtered subscriptions are ordered in same queue

• Subscription PriorityOrder

  • uses C5.TreeSet for performance

• Unsubscribe by object handle

  • allows unsubscribing handle from middle of queue

• Automatic pooling for Subscriptions

• ISignalData types are short lived objects that are passed through invoke call stack

  • use SignalHub.I.Pub( new SignalData() ) for publishing message
    • struct signalDatas are passed by reference between subscriptions
    • Pub returns modified struct signalData

• Allows more than 1 EventAggregator through SignalHubLocal instances

• IoC AbstractFactory/Facade class wraps concrete classes into virtual methods, allowing inheriting IoC to override them

• Subscribing to currently publishing ISignalData behavior:

  • will run new subscriptions with SAME or HIGHER priorityOrder compared to priorityOrder of currently invoked subscription
  • will NOT run new subscriptions with LOWER priorityOrder compared to priorityOrder of currently invoked subscription

• Publishing signalData inside callback works as regular call stack(runs new publish as separate call, then continues where it left off)

  • Example:
    • There are 3 subscriptions to type MessageA: s1, s2, s3
    • s2 has Publish(MessageA m2) inside its callback
    • some function calls Publish(MessageA m1)
    • callbacks trigger in order : s1(m1), s2(m1), s1(m2), s2(m2), s3(m2), s3(m1)

Usage

public class Example
{
  private void SubPubUnsub()
  {
    // Subscribe
    var subFiltered = SignalHub.I.Sub<Message>( filter: this, OnMessageFiltered );
    var sub = SignalHub.I.Sub<Message>( OnMessage );
    var subPriority = SignalHub.I.Sub<Message>( OnMessagePriority, order: -5 );

    // Publish
    SignalHub.I.Pub(new Message("no filter")); // Callbacks: HandlePriority(), Handle()
    SignalHub.I.Pub(filter: this, new Message("with filter")); // Callbacks: HandlePriority(), HandleFiltered(), Handle()

    // Unsubscribe
    SignalHub.I.Unsub(sub);
    SignalHub.I.Unsub(subFiltered);
    SignalHub.I.Unsub(subPriority);
  }

  private void OnMessage(ref Message message) {  }
  private void OnMessageFiltered(ref Message message) {  }
  private void OnMessagePriority(ref Message message) {  }
}

// struct messages are recommended for less Garbage Collection
public struct Message : ISignalData
{
  public Message(string value)
  {
    Value = value;
  }

  public string Value;
}

TODO

• Cover with tests case when subscriptions collection gets rehashed and keeps order of elements in matching priority chains.