Function nc::poll

pub unsafe fn poll(fds: &mut [pollfd_t], timeout: i32) -> Result<i32, Errno>

Wait for some event on file descriptors.

The timeout argument specifies the number of milliseconds that poll() should block waiting for a file descriptor to become ready. Specifying a timeout of zero causes poll() to return immediately, even if no file descriptors are ready.

Return value

On success, it returns a nonnegative value which is the number of events in the fds whose revents fields have been set to a nonzero value.

Examples

use std::thread;
use std::time::Duration;

const STDIN_FD: i32 = 0;
const STDOUT_FD: i32 = 1;

fn main() {
    let mut fds = [
        nc::pollfd_t {
            fd: STDIN_FD,
            events: nc::POLLIN,
            revents: 0,
        },
        nc::pollfd_t {
            fd: STDOUT_FD,
            events: nc::POLLOUT,
            revents: 0,
        },
    ];

    // Create a background thread to print some messages to stdout.
    let handle = thread::spawn(|| {
        thread::sleep(Duration::from_millis(100));
        println!("MESSAGES from rust");
    });

    let ret = unsafe { nc::poll(&mut fds, 3000) };
    assert!(ret.is_ok());
    let num_ready = ret.unwrap();
    println!("num of fds ready to read: {num_ready}");
    assert!(handle.join().is_ok());
}