private void LinkHandlers(MessageHandlerBase prev, MessageHandlerBase next)
{
if (prev != null)
{
if (next != null)
{
prev.NextHandler = next.HandleUpstreamMessage;
prev.ChannelActivated = next.OnChannelActivated;
}
else
{
prev.NextHandler = null;
prev.ChannelActivated = null;
}
}
if (next != null)
{
if (prev != null)
{
next.PrevHandler = prev.HandleDownstreamMessage;
}
else
{
next.PrevHandler = null;
}
}
}
private MessageHandlerBase FindNextFirstActiveHandler(int startIndex)
{
while (startIndex < _handlers.Count - 1)
{
startIndex++;
MessageHandlerBase handler = _handlers[startIndex];
if (handler.IsActive)
{
return(handler);
}
}
return(null);
}
private MessageHandlerBase FindPrevFirstActiveHandler(int startIndex)
{
while (startIndex > 0)
{
startIndex--;
MessageHandlerBase handler = _handlers[startIndex];
if (handler.IsActive)
{
return(handler);
}
}
return(null);
}
public void Add(MessageHandlerBase handler)
{
handler.IsActive = true;
handler.Pipeline = this;
if (_firstHandler == null)
{
LinkFirstHandler(handler);
}
else
{
MessageHandlerBase lastHandler = _handlers.Count > 0
? _handlers[_handlers.Count - 1]
: null;
LinkHandlers(lastHandler /* prev */, handler /* next */);
}
_handlers.Add(handler);
}
public void DeactivateHandler(MessageHandlerBase handler)
{
handler.IsActive = false;
int handlerIndex = _handlers.IndexOf(handler);
MessageHandlerBase prevHandler = FindPrevFirstActiveHandler(handlerIndex);
MessageHandlerBase nextHandler = FindNextFirstActiveHandler(handlerIndex);
if (prevHandler == null && nextHandler == null)
{
throw new Exception("No handlers remain.");
}
LinkHandlers(prevHandler, nextHandler);
if (prevHandler == null)
{
// Текущий хэндлер был первым. Линкуем следующий хэндлер как первый.
LinkFirstHandler(nextHandler);
}
}
private void LinkFirstHandler(MessageHandlerBase firstHandler)
{
_firstHandler = firstHandler;
_firstHandler.PrevHandler = SendToChannel;
}
