How to make 'send' non-blocking in winsock
Solution 1
The API ioctlsocket can do it.You can use it as below.But why don't you use I/O models in winsock?
ioctlsocket(hsock,FIOBIO,(unsigned long *)&ul);
Solution 2
You need to use a non-blocking socket. The send/receive functions are the same functions for blocking or non-blocking operations, but you must set the socket itself to non-blocking.
u_long mode = 1; // 1 to enable non-blocking socket
ioctlsocket(sock, FIONBIO, &mode);
Also, be aware that working with non-blocking sockets is quite different. You'll need to make sure you handle WSAEWOULDBLOCK errors as success! :)
So, using non-blocking sockets may help, but still will not guarantee an exact period. You would be better to drive this from a timer, rather than this simple loop, so that any latency from calling send, even in non-blocking mode, will not affect the timing.
Zhi Wang
Updated on June 17, 2022Comments
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Zhi Wang almost 2 years
I am making a program which sends UDP packets to a server at a fixed interval, something like this:
while (!stop) { Sleep(fixedInterval); send(sock, pkt, payloadSize, flags); }
However the periodicity cannot be guaranteed because
send
is a blocking call (e.g., whenfixedInterval
is 20ms, and a call tosend
is > 20ms ). Do you know how I can turn thesend
into a non-blocking operation?