I have implemented some connection classes, using Boost ASIO, to replace some low level C code in an application, and everything is working great, except for one problem.

Basically, I have a UdpConnection class that does synchronous read and write, but it uses async methods to handle time-outs as per the boost examples.  The problem is I can't figure out how to make it threadsafe.

I have tried adding strands to the event handlers to make this class threadsafe (code below), but that isn't working.  I suspect it is because of the way timeout is implemented. I have included my code in 4 classes in pastebin.

Single threaded is working fine.  I also have TcpConnection and UnixSocketConnection classes that don't need to be shared amongst multiple threads and they work fine.  However, I can't get multi-threaded UDP code to work.

Am I missing something?  Sources below: