/// <summary>
/// Listens for a message with the given type and predicate once and then stops listening
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="broker"></param>
/// <param name="handler"></param>
/// <returns></returns>
public static ListenerToken ListenOnce <T>(this IMessageBroker broker, Predicate <T> predicate, Action <T> handler) where T : Message
{
if (handler == null)
{
throw new ArgumentNullException("handler");
}
ListenerToken token = null;
Action <T> handlerWrapped = new Action <T>(t =>
{
// Stop listening first then pass to the handler
if (t.Exception != null)
{
token.StopListening(t.Exception);
return;
}
token.StopListening();
handler(t);
});
token = broker.Listen <T>(predicate, handlerWrapped);
return(token);
}
//////////////////////////////////////////////////////////////////////
#region Public Methods
/// <summary>
/// Awaits a response to the message associated with the MessageToken
/// </summary>
/// <returns>A Task object which can be awaited on until a response is received to the Message</returns>
public async Task AwaitResponse()
{
ListenerToken token = null;
token = broker.ListenOnce <Message>(m => m.ReferenceId == message.Id);
await token.Completion;
}
/// <summary>
/// Awaits a response to the message associated with the MessageToken with a given response message
/// </summary>
/// <typeparam name="TResult"></typeparam>
/// <returns>A Task object which can be awaited on until a response is received to the Message</returns>
public async Task <T> AwaitResponse <T>() where T : Message
{
ListenerToken token = null;
T result = default(T);
token = broker.ListenOnce <T>(m => m.ReferenceId == message.Id, m =>
{
result = m;
});
await token.Completion;
return(result);
}