Is there a way to check whether the data buffer for a socket is empty or not in python?

Question

I want to verify if the socket data buffer is empty or not before calling socket.recv(bufsize[, flags]). Is there a way to do that?

Answer 1

You can peek (look without actually consuming the data):

data = conn.recv(bufsize, socket.MSG_PEEK)

Answer 2

You might want to make your socket non-blocking:

socket.setblocking(0)

After that call, if you read from a socket without available data it will not block, but instead an exception is raised. See socket.setblocking(flag) for details.

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For more advanced uses, you might look at select. Something like:

r, _, _ = select([socket],[],[],0)
#                               ^
#           Timeout of 0 to poll (and not block)

Will inform you if some data are available to read in your socket.