Struct oneshot::Receiver

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

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>

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.

Panics

Panics if called after this receiver has been polled asynchronously.

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

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.

Panics

Panics if called after this receiver has been polled asynchronously.

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

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.

Panics

Panics if called after this receiver has been polled asynchronously.

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

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.

Panics

Panics if called after this receiver has been polled asynchronously.

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> Future for Receiver<T>

type Output = Result<T, RecvError>

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.

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

impl<T> Unpin for Receiver<T>