NAME

nn_poll - poll sockets (compatible API)

SYNOPSIS

#include <nanomsg/nn.h>
#define NN_POLLIN  1
#define NN_POLLOUT 2
struct nn_pollfd {


    int      fd;


    uint16_t events;


    uint16_t revents;
};
int nn_poll(struct nn_pollfd *pfds, int npfd, int timeout);

DESCRIPTION

The nn_poll() function polls a group of sockets for readiness to send or receive.

The array of nfds sockets to poll for are passed into pfds. Each member of this array is initialized with the fd field set to the socket, and the events field set to a mask that can contain either or both of the flags NN_POLLIN and NN_POLLOUT.

The flag NN_POLLIN indicates that a socket is ready for receiving without blocking (a message is available on the socket), and the flag NN_POLLOUT indicates that a socket is ready for sending without blocking.

Upon success, the function returns the number of updates the revents field of each member of the pfds array, setting it to indicate whether the requested status is true or not.

If the timeout field is positive, then this function will wait for up the that many milliseconds. If none of the requested events occurs before that timeout occurs, then the function will return -1 and set the error to ETIMEDOUT.

If the timeout is zero, then this function will return immediately, after updating the current status of the sockets.

If the timeout is -1, then the function waits forever, or until one of the requested events occurs.

RETURN VALUES

This function returns the number of sockets with events on success, or -1 on error.

ERRORS

ENOMEM

EBADF

ETIMEDOUT

ENOTSUP

SEE ALSO

nn_errno(3compat), nn_recv(3compat), nn_send(3compat), nn_socket(3compat), nn_compat(3compat), nng(7)