Struct MessageStream 

pub struct MessageStream { /* private fields */ }

Represents an open subscribe stream.

This is a stream-like struct for serving messages to an application.

Example

let mut stream = client
    .subscribe("projects/my-project/subscriptions/my-subscription")
    .build();
while let Some((m, h)) = stream.next().await.transpose()? {
    println!("Received message m={m:?}");
    h.ack();
}

Implementations

impl MessageStream

pub async fn next(&mut self) -> Option<Result<(Message, Handler)>>

Returns the next message received on this subscription.

Example

while let Some((m, h)) = stream.next().await.transpose()? {
    println!("Received message m={m:?}");
    h.ack();
}

Returns the message data along with a Handler to acknowledge (ack) the message.

If the underlying stream encounters a permanent error, an Error is returned instead.

None represents the end of a stream, but in practice, the stream stays open until it is cancelled or encounters a permanent error.

pub fn into_stream( self, ) -> impl Stream<Item = Result<(Message, Handler)>> + Unpin

Available on crate feature unstable-stream only.

Converts the MessageStream to a futures::Stream.

Example

use futures::TryStreamExt;
let mut stream = stream.into_stream();
while let Some((m, h)) = stream.try_next().await? { /* ... */ }

pub fn shutdown_token(&self) -> ShutdownToken

Returns a shutdown token for the stream.

Example

// Get a shutdown token for the stream.
let shutdown_token = stream.shutdown_token();

// Signal and await a shutdown of the stream.
shutdown_token.shutdown().await;

// The stream stops yielding messages after shutdown is signaled.
assert!(stream.next().await.is_none());

Use this token to signal and/or await shutdown of the stream.

Awaiting a stream shutdown gives the subscriber time to flush its pending acknowledgements, and schedule other messages for redelivery to another client as soon as possible.

Trait Implementations

impl Debug for MessageStream

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

Formats the value using the given formatter.