[asio-users] querying for active async operations

[Arvid N. <c9...@cs...>]

Hi.

I have a stream_socket, and I want to throttle the bandwidth it uses  
for the data I send and receive on that socket. Right now I have  
implemented this as a per second quota. When the socket runs out of  
quota it won't receive anything until the next second, when it's  
restored again.

The use pattern for receiving seems to be:

main()
{
   socket.async_read_some(handler, ...);
   demuxer.run();
}

void handler(...)
{
    // process received data
    socket.async_read_some(handler, ...);
}

Something like that. Now that I want to throttle the download speed;  
at the end of the handler I sometimes don't want to call  
async_read_some(), because the download quota for this second is  
already used up. But in some situations, where the quota is much  
bigger than the actual transfer rate, it will always call  
async_read_some() at the end.

Now, every time I reset the receive quota, I will have to check:
"am I currently waiting for data or should I call async_read_some()  
now?"

This would be pretty easy to know, just by storing that state with my  
connection, but maybe it could be useful to be able to query the  
socket for that too. I'm not sure if it's really a good idea, since  
the interface is pretty big as it is though, but at least it would  
make the invariance of my connection class easier to maintain.

And, btw, is this a stupid way of throttling the download speed?  
(assuming there's no protocol support that can tell the other side to  
throttle its send rate).

thanks.

--
Arvid Norberg