Struct mio::Waker[][src]

pub struct Waker { /* fields omitted */ }

Waker allows cross-thread waking of Poll.

When created it will cause events with readable readiness and the provided token if wake is called, possibly from another thread.


Waker events are only guaranteed to be delivered while the Waker value is alive.

Only a single Waker can be active per Poll, if multiple threads need access to the Waker it can be shared via for example an Arc. What happens if multiple Wakers are registered with the same Poll is undefined.

Implementation notes

On platforms that support kqueue this will use the EVFILT_USER event filter, see implementation notes of Poll to see what platforms support kqueue. On Linux it uses eventfd.


Wake a Poll instance from another thread.

use std::thread;
use std::time::Duration;
use std::sync::Arc;

use mio::{Events, Token, Poll, Waker};

const WAKE_TOKEN: Token = Token(10);

let mut poll = Poll::new()?;
let mut events = Events::with_capacity(2);

let waker = Arc::new(Waker::new(poll.registry(), WAKE_TOKEN)?);

// We need to keep the Waker alive, so we'll create a clone for the
// thread we create below.
let waker1 = waker.clone();
let handle = thread::spawn(move || {
    // Working hard, or hardly working?

    // Now we'll wake the queue on the other thread.
    waker1.wake().expect("unable to wake");

// On our current thread we'll poll for events, without a timeout.
poll.poll(&mut events, None)?;

// After about 500 milliseconds we should be awoken by the other thread and
// get a single event.
let waker_event = events.iter().next().unwrap();
assert_eq!(waker_event.token(), WAKE_TOKEN);


impl Waker[src]

pub fn new(registry: &Registry, token: Token) -> Result<Waker>[src]

Create a new Waker.

pub fn wake(&self) -> Result<()>[src]

Wake up the Poll associated with this Waker.

Trait Implementations

impl Debug for Waker[src]

Auto Trait Implementations

impl RefUnwindSafe for Waker

impl Send for Waker

impl Sync for Waker

impl Unpin for Waker

impl UnwindSafe for Waker

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized

impl<T> Borrow<T> for T where
    T: ?Sized

impl<T> BorrowMut<T> for T where
    T: ?Sized

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.