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NN_POLL(3)			 nanomsg 1.1.5			    NN_POLL(3)

NAME
       nn_poll - poll a	set of SP sockets for readability and/or writability

SYNOPSIS
       #include	<nanomsg/nn.h>

       int nn_poll (struct nn_pollfd *fds, int nfds, int timeout);

DESCRIPTION
       The function checks a set of SP socket and reports whether it's
       possible	to send	a message to the socket	and/or receive a message from
       each socket.

       fds argument is an array	of nn_pollfd structures	with nfds argument
       specifying the size of the array:

	   struct nn_pollfd {
	       int fd;
	       short events;
	       short revents;
	   };

       Each entry in the array represents an SP	socket to check. events	field
       specifies which events to check for. The	value is a bitwise combination
       of the following	values:

       NN_POLLIN
	   Check whether at least one message can be received from the fd
	   socket without blocking.

       NN_POLLOUT
	   Check whether at least one message can be sent to the fd socket
	   without blocking.

       After the function returns, revents field contains bitwise combination
       of NN_POLLIN and	NN_POLLOUT according to	whether	the socket is readable
       or writable.

       timeout parameter specifies how long (in	milliseconds) should the
       function	block if there are no events to	report.

RETURN VALUE
       Upon successful completion, the number of nn_pollfds structures with
       events signaled is returned. In case of timeout,	return value is	0. In
       case of error, -1 is returned and errno is set the one of the values
       below.

ERRORS
       EBADF
	   Some	of the provided	sockets	are invalid.

       EINTR
	   The operation was interrupted by delivery of	a signal before	the
	   message was sent.

       ETERM
	   The library is terminating.

NOTE
       nn_poll is a convenience	function. You can achieve same behaviour by
       using NN_RCVFD and NN_SNDFD socket options. However, using the socket
       options allows for usage	that's not possible with nn_poll, such as
       simultaneous polling for	both SP	and OS-level sockets, integration of
       SP sockets with external	event loops etc.

EXAMPLE
	   struct nn_pollfd pfd	[2];
	   pfd [0].fd =	s1;
	   pfd [0].events = NN_POLLIN |	NN_POLLOUT;
	   pfd [1].fd =	s2;
	   pfd [1].events = NN_POLLIN;
	   rc =	nn_poll	(pfd, 2, 2000);
	   if (rc == 0)	{
	       printf ("Timeout!");
	       exit (1);
	   }
	   if (rc == -1) {
	       printf ("Error!");
	       exit (1);
	   }
	   if (pfd [0].revents & NN_POLLIN) {
	       printf ("Message	can be received	from s1!");
	       exit (1);
	   }

SEE ALSO
       nn_socket(3) nn_getsockopt(3) nanomsg(7)

AUTHORS
       Martin Sustrik <sustrik@250bpm.com>

				  2018-10-15			    NN_POLL(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTE | EXAMPLE | SEE ALSO | AUTHORS

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