boost::asio udp socket read and write

Question

I need an advice with the situation

I'm doing a udp async multicast transiver :

• he can accepts data from multicast group
• he can send data to multicast group

Data is sent in the following cases:

• async_receive_from -> callback -> async_send (in the same thread)
• by external timer -> async_send(in another thread)

1. I use one socket for receive and send . Do I need synchronize async_receive_from and async_send_to from external timer? booast::asio doc says that objects are unsafe. My solution is use a ioserivce post/dispatch for external timer data, that async_send_to call in the same thread

2. If I make two sockets - one for read, one for thread, who works this one multicast groud. Do I need synchronize this?

PS I'm using one thread ioservice::run

Answer 1

As soon as an external timer is involved likely a strand is required for synchronization. The only exception is when the service is restricted to a single thread already - and the "external timer" trigger originates from that same thread. This is called the implicit strand.