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I would like to know if the following scenario is real?!
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recv(IPC, Buffer, int n) is a blocking call, that is, if data is available it writes it to the buffer and immediately returns true, and if no data is available it waits for at least n seconds to receive any data.
recv will block until the entire buffer is filled, or the socket is closed. If you want to read length bytes and return, then you must only pass to recv a buffer of size length . This can avoid recv from blocking.
If a datagram packet is too long to fit in the supplied buffer, datagram sockets discard excess bytes. If data is not available for the socket socket, and socket is in blocking mode, the recv() call blocks the caller until data arrives.
To mark a socket as non-blocking, we use the fcntl system call. Here's an example: int flags = guard(fcntl(socket_fd, F_GETFL), "could not get file flags"); guard(fcntl(socket_fd, F_SETFL, flags | O_NONBLOCK), "could not set file flags"); Here's a complete example.
It's possible, but only in a situation where you have multiple threads/processes trying to read from the same socket.
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For recv() you would get EAGAIN rather than EWOULDBLOCK, and yes it is possible. Since you have just checked with select() then one of two things happened:
select() and recv().
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