/// <summary>
/// Publish the specified change record to all <see cref="Subscribers"/>.
/// </summary>
/// <param name="changeRecord">The change record to publish.</param>
/// <exception cref="ArgumentNullException"><paramref name="changeRecord"/> is <see langword="null" />.</exception>
public void Publish(ChangeRecord changeRecord)
{
if (changeRecord == null)
{
throw new ArgumentNullException(nameof(changeRecord));
}
// local snapshot of subscribers
ISubscription[] subscribers;
lock (_subscribers)
subscribers = _subscribers.ToArray();
// notify all subscribers that are active and match filter
var deadSubscribers = subscribers
.Where(h => IsMatch(changeRecord, h.Filter))
.Where(h => !h.BeginInvoke(changeRecord))
.ToList();
if (deadSubscribers.Count == 0)
{
return;
}
// remove dead subscribers
lock (_subscribers)
foreach (var d in deadSubscribers)
{
_subscribers.Remove(d);
}
}
private bool IsMatch(ChangeRecord changeRecord, string filter)
{
if (string.IsNullOrWhiteSpace(filter))
{
return(true);
}
return(changeRecord.Namespace.Like(filter));
}
/// <summary>
/// Begin invoke of <see cref="Handler"/> on the thread-pool background thread.
/// </summary>
/// <param name="change">The change record to send.</param>
/// <returns><c>true</c> if the Handler is still alive and was able to be invoked; otherwise <c>false</c>.</returns>
public bool BeginInvoke(ChangeRecord change)
{
// handler might have been disposed
var handler = _reference.Target as IHandleChange;
if (handler == null)
{
return(false);
}
// fire and forget
return(ThreadPool.QueueUserWorkItem(state => handler.HandleChange(change)));
}
