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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 speci- fying 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 er- ror, -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 mes- sage 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 al- lows 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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