# tokio::sync::mpsc::UnboundedReceiver - Rust
API documentation for the Rust `UnboundedReceiver` struct in crate `tokio`.
Keywords: rust, rustlang, rust-lang, UnboundedReceiver

# Struct tokio::sync::mpsc::UnboundedReceiver [−] [src]

    pub struct UnboundedReceiver<T> { /* fields omitted */ }

Receive values from the associated `UnboundedSender`.

Instances are created by the `unbounded_channel` function.

This receiver can be turned into a `Stream` using `UnboundedReceiverStream`.

## Implementations

### `impl<T> UnboundedReceiver<T>` [src]

#### `pub async fn recv(&mut self) -> Option<T>` [src]

Receives the next value for this receiver.

`None` is returned when all `Sender` halves have dropped, indicating that no further values can be sent on the channel.

# Examples

    use tokio::sync::mpsc;

    #[tokio::main]
    async fn main() {
        let (tx, mut rx) = mpsc::unbounded_channel();

        tokio::spawn(async move {
            tx.send("hello").unwrap();
        });

        assert_eq!(Some("hello"), rx.recv().await);
        assert_eq!(None, rx.recv().await);
    }

Values are buffered:

    use tokio::sync::mpsc;

    #[tokio::main]
    async fn main() {
        let (tx, mut rx) = mpsc::unbounded_channel();

        tx.send("hello").unwrap();
        tx.send("world").unwrap();

        assert_eq!(Some("hello"), rx.recv().await);
        assert_eq!(Some("world"), rx.recv().await);
    }

#### `pub fn blocking_recv(&mut self) -> Option<T>` [src]

Blocking receive to call outside of asynchronous contexts.

# Panics

This function panics if called within an asynchronous execution context.

# Examples

    use std::thread;
    use tokio::sync::mpsc;

    #[tokio::main]
    async fn main() {
        let (tx, mut rx) = mpsc::unbounded_channel::<u8>();

        let sync_code = thread::spawn(move || {
            assert_eq!(Some(10), rx.blocking_recv());
        });

        let _ = tx.send(10);
        sync_code.join().unwrap();
    }

#### `pub fn close(&mut self)` [src]

Closes the receiving half of a channel, without dropping it.

This prevents any further messages from being sent on the channel while still enabling the receiver to drain messages that are buffered.

#### `pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<T>>` [src]

Polls to receive the next message on this channel.

This method returns:

- `Poll::Pending` if no messages are available but the channel is not closed.
- `Poll::Ready(Some(message))` if a message is available.
- `Poll::Ready(None)` if the channel has been closed and all messages sent before it was closed have been received.

When the method returns `Poll::Pending`, the `Waker` in the provided `Context` is scheduled to receive a wakeup when a message is sent on any receiver, or when the channel is closed. Note that on multiple calls to `poll_recv`, only the `Waker` from the `Context` passed to the most recent call is scheduled to receive a wakeup.

## Trait Implementations

### `impl<T> Debug for UnboundedReceiver<T>` [src]

#### `fn fmt(&self, fmt: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

## Auto Trait Implementations

### `impl<T> !RefUnwindSafe for UnboundedReceiver<T>` [src]

### `impl<T> Send for UnboundedReceiver<T> where
T: Send,` [src]

### `impl<T> Sync for UnboundedReceiver<T> where
T: Send,` [src]

### `impl<T> Unpin for UnboundedReceiver<T>` [src]

### `impl<T> !UnwindSafe for UnboundedReceiver<T>` [src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
` [src]

Mutably borrows from an owned value. Read more

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

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

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

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.