Struct Subscription

pub struct Subscription<Notif> { /* private fields */ }

Available on crate feature client only.

Represent a client-side subscription which is implemented on top of a bounded channel where it’s possible that the receiver may not keep up with the sender side a.k.a “slow receiver problem”

The Subscription will try to unsubscribe in the drop implementation but it may fail if the underlying buffer is full. Thus, if you want to ensure it’s actually unsubscribed then Subscription::unsubscribe is recommended to use.

Lagging

All messages from the server must be kept in a buffer in the client until they are read by polling the Subscription. If you don’t poll the client subscription quickly enough, the buffer may fill up and when subscription is full the subscription is then closed.

You can call Subscription::close_reason to determine why the subscription was closed.

Implementations

impl<Notif> Subscription<Notif>

pub fn kind(&self) -> &SubscriptionKind

Return the subscription type and, if applicable, ID.

pub async fn unsubscribe(self) -> Result<(), Error>

Unsubscribe and consume the subscription.

pub fn close_reason(&self) -> Option<SubscriptionCloseReason>

The reason why the subscription was closed.

Returns Some(reason) is the subscription was closed otherwise None is returned.

impl<Notif> Subscription<Notif>

where Notif: DeserializeOwned,

pub async fn next(&mut self) -> Option<Result<Notif, Error>>

Returns the next notification from the stream. This may return None if the subscription has been terminated, which may happen if the channel becomes full or is dropped.

Note: This has an identical signature to the StreamExt::next method (and delegates to that). Import StreamExt if you’d like access to other stream combinator methods.

Trait Implementations

impl<Notif: Debug> Debug for Subscription<Notif>

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

Formats the value using the given formatter.

impl<Notif> Drop for Subscription<Notif>

fn drop(&mut self)

Executes the destructor for this type.

impl<Notif> Stream for Subscription<Notif>

where Notif: DeserializeOwned,

type Item = Result<Notif, Error>

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.

impl<Notif> Unpin for Subscription<Notif>