Struct relay_system::BroadcastChannel

pub struct BroadcastChannel<T>
where
    T: Clone,
{ /* private fields */ }

A channel that broadcasts values to attached senders.

This is part of the BroadcastResponse message behavior to efficiently send delayed responses to a large number of senders. All requests that are attached to this channel via their senders resolve with the same value.

Example

use relay_system::{BroadcastChannel, BroadcastSender};

struct MyService {
    channel: Option<BroadcastChannel<String>>,
}

impl MyService {
    fn handle_message(&mut self, sender: BroadcastSender<String>) {
        if let Some(ref mut channel) = self.channel {
            channel.attach(sender);
        } else {
            self.channel = Some(sender.into_channel());
        }
    }

    fn finish_compute(&mut self, value: String) {
        if let Some(channel) = self.channel.take() {
            channel.send(value);
        }
    }
}

Implementations

impl<T: Clone> BroadcastChannel<T>

pub fn new() -> Self

Creates a standalone channel.

Use attach to add senders to this channel. Alternatively, create a channel with BroadcastSender::into_channel.

pub fn attach(&mut self, sender: BroadcastSender<T>)

Attaches a sender of another message to this channel to receive the same value.

Example

use relay_system::{BroadcastChannel, BroadcastResponse, BroadcastSender};

// This is usually done as part of `Addr::send`
let (sender, rx) = BroadcastResponse::<&str>::channel();

let mut channel = BroadcastChannel::new();
channel.attach(sender);

pub fn send(self, value: T)

Sends a value to all attached senders and closes the channel.

This method succeeds even if no senders are attached to this channel anymore. To check if this channel is still active with senders attached, use is_attached.

Example

use relay_system::BroadcastResponse;

// This is usually done as part of `Addr::send`
let (sender, rx) = BroadcastResponse::<&str>::channel();

let channel = sender.into_channel();
channel.send("test");
assert_eq!(rx.await, Ok("test"));

pub fn is_attached(&self) -> bool

Returns true if there are requests waiting for this channel.

The channel is not permanently closed when all waiting requests have detached. A new sender can be attached using attach even after this method returns false.

Example

use relay_system::BroadcastResponse;

// This is usually done as part of `Addr::send`
let (sender, rx) = BroadcastResponse::<&str>::channel();

let channel = sender.into_channel();
assert!(channel.is_attached());

drop(rx);
assert!(!channel.is_attached());

Trait Implementations

impl<T> Debug for BroadcastChannel<T>

where T: Clone + Debug,

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

Formats the value using the given formatter.

impl<T: Clone> Default for BroadcastChannel<T>

fn default() -> Self

Returns the “default value” for a type.