Event Manager using signals and threads

Question

I'd like to know what is the best way to build a multi-threaded event system using Boost::signals2 and Boost::thread.

In my project, I have a network class that listen to incoming connection in a thread. When a player connects, the class should be able to raise an event to my server handler class and other functions listening to the signal. Thing is, the server and the other functions can be in threads too, and the called function MUST NOT be withing the network class context, but within the context that subscribed to the event.

What is the best way to do this? I have heard of polling but I'm not sure how this can be used here, using threads and signals.

tldr: Be able to listen to signals that are in other threads.

score 2 · Answer 1 · answered Nov 07 '11 at 15:16

2

As far as I understand, boost signals2 doesn't give you what you want. It's thread safe, but it can't execute code on another thread for you.

It sounds to me like you should put events into a queue rather than trying to use signals. Your consumer thread can simply block until an event is available in the queue.

Is there a requirement that you must use signals as part of your solution?

answered Nov 07 '11 at 15:16

Nathanael

1,782
17
25

It's for a game server. So I have to manage many events happening and dispatch them to different classes. I'm looking for a centralized way to do it. Signals give me the possibility to bind functions to events and to have more than one function binded to it. So according to your answer, should I use a thread-safe queue of binded functions within my consumer class? – Blizter Nov 07 '11 at 15:28
Yes, you could do that. I think you'd be reinventing the wheel though - you really want more of a message queue. I think Ralf's answer will be a good starting point for that. – Nathan Monteleone Nov 07 '11 at 15:41

score 2 · Accepted Answer · edited May 23 '17 at 12:03

Since you're writing network-based code in anyway, have you considered boost asio?

To elaborate briefly, calling boost::asio::io_service::run from multiple threads allows you to handle events in a multi-threaded manner. Further, you can post work to the io_service using io_service::post, which will cause the work to get executed by the io_service in the threads that are blocked on the run method. For more info, read this SO post. The game-dev link provides a nice introduction to asio and to how it can be used. asio also provides a poll method, and much much more.

To me it sounds like asio is a nice fit for what you are trying to achieve.

Event Manager using signals and threads

2 Answers2