Struct Receiver 

pub struct Receiver<T> { /* private fields */ }

Receiving end of a oneshot channel.

Created and returned from the channel function.

Can be used to receive a message from the corresponding Sender. How the message can be received depends on what features are enabled.

This type implements IntoFuture when the async feature is enabled. This allows awaiting it directly in an async context.

Implementations

impl<T> Receiver<T>

pub fn try_recv(&self) -> Result<T, TryRecvError>

Checks if there is a message in the channel without blocking. Returns:

• Ok(message) if there was a message in the channel.
• Err(Empty) if the Sender is alive, but has not yet sent a message.
• Err(Disconnected) if the Sender was dropped before sending anything or if the message has already been extracted by a previous receive call.

If a message is returned, the channel is disconnected and any subsequent receive operation using this receiver will return an error.

This method is completely lock-free and wait-free. The only thing it does is an atomic integer load of the channel state. And if there is a message in the channel it additionally performs one atomic integer store and copies the message from the heap to the stack for returning it.

pub fn recv(self) -> Result<T, RecvError>

Available on crate feature std only.

Attempts to wait for a message from the Sender, returning an error if the channel is disconnected.

This method will always block the current thread if there is no data available and it is still possible for the message to be sent. Once the message is sent to the corresponding Sender, then this receiver will wake up and return that message.

If the corresponding Sender has disconnected (been dropped), or it disconnects while this call is blocking, this call will wake up and return Err to indicate that the message can never be received on this channel.

If a sent message has already been extracted from this channel this method will return an error.

pub fn recv_ref(&self) -> Result<T, RecvError>

Available on crate feature std only.

Attempts to wait for a message from the Sender, returning an error if the channel is disconnected. This is a non consuming version of Receiver::recv, but with a bit worse performance. Prefer [Receiver::recv] if your code allows consuming the receiver.

If a message is returned, the channel is disconnected and any subsequent receive operation using this receiver will return an error.

pub fn recv_timeout(&self, timeout: Duration) -> Result<T, RecvTimeoutError>

Available on crate feature std only.

Like Receiver::recv, but will not block longer than timeout. Returns:

• Ok(message) if there was a message in the channel before the timeout was reached.
• Err(Timeout) if no message arrived on the channel before the timeout was reached.
• Err(Disconnected) if the sender was dropped before sending anything or if the message has already been extracted by a previous receive call.

If a message is returned, the channel is disconnected and any subsequent receive operation using this receiver will return an error.

If the supplied timeout is so large that Rust’s Instant type can’t represent this point in the future this falls back to an indefinitely blocking receive operation.

pub fn recv_deadline(&self, deadline: Instant) -> Result<T, RecvTimeoutError>

Available on crate feature std only.

Like Receiver::recv, but will not block longer than until deadline. Returns:

• Ok(message) if there was a message in the channel before the deadline was reached.
• Err(Timeout) if no message arrived on the channel before the deadline was reached.
• Err(Disconnected) if the sender was dropped before sending anything or if the message has already been extracted by a previous receive call.

If a message is returned, the channel is disconnected and any subsequent receive operation using this receiver will return an error.

pub fn is_closed(&self) -> bool

Returns true if the associated Sender was dropped before sending a message. Or if the message has already been received.

If true is returned, all future calls to receive methods are guaranteed to return a disconnected error. And future calls to this method is guaranteed to also return true.

pub fn has_message(&self) -> bool

Returns true if there is a message in the channel, ready to be received.

If true is returned, the next call to a receive method is guaranteed to return a message.

pub fn into_raw(self) -> *mut ()

Consumes the Receiver, returning a raw pointer to the channel on the heap.

This is intended to simplify using oneshot channels with some FFI code. The only safe thing to do with the returned pointer is to later reconstruct the Receiver with Receiver::from_raw. Memory will leak if the Receiver is never reconstructed.

pub unsafe fn from_raw(raw: *mut ()) -> Self

Consumes a raw pointer from Receiver::into_raw, recreating the Receiver.

Safety

This pointer must have come from Receiver<T>::into_raw with the same message type, T. At most one Receiver must exist for a channel at any point in time. Constructing multiple Receivers from the same raw pointer leads to undefined behavior.

Trait Implementations

impl<T: Debug> Debug for Receiver<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Drop for Receiver<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T> IntoFuture for Receiver<T>

Available on crate feature async only.

type Output = Result<T, RecvError>

The output that the future will produce on completion.

type IntoFuture = AsyncReceiver<T>

Which kind of future are we turning this into?

fn into_future(self) -> Self::IntoFuture

Creates a future from a value.

impl<T: Send> Send for Receiver<T>

impl<T> Unpin for Receiver<T>