Module Netsys_pollset_win32

This is a pollset implementation that works for

• sockets, and
• named pipes as provided by Netsys_win32 (add the descriptors returned by pipe_descr or pipe_server_descr to the pollset)

The number of descriptors that can be added to the pollset has a quite low limit (usually 63 sockets or 31 pipes). If the number is exceeded the exception Too_many_descriptors is raised (by add).

POLLERR, POLLHUP, and POLLNVAL are not detected by this impl.

This implementation overcomes the limit on the number of descriptors one can add to the set. It is, however, only available for multi-threaded programs, because it uses helper threads.