P(ringbuffer_free);
ringbuffer[ringbuffer_write] = client_socket;
ringbuffer_write = (ringbuffer_write + 1) % RINGBUFFER_SIZE;
P(ringbuffer_free);
ringbuffer[ringbuffer_write] = client_socket;
ringbuffer_write = (ringbuffer_write + 1) % RINGBUFFER_SIZE;