I think the manual page for SOCK_RECV is confusing and would like to see a change similar to the following.
Change
QuoteThe return value could mean:
-2 : a non blocking socket is not ready to be read and would block. Try reading from that socket a bit later.
to
QuoteThe return value could mean:
-2 : there are no network messages currently in the queue waiting to be processed. Try reading from that socket a bit later.
As it is currently written it's not clear how you determine whether there are network messages waiting to be processed or not.