[−][src]Trait lifeline::CarryFrom

pub trait CarryFrom<FromBus: Bus>: Bus + Task + Sized {
    type Lifeline;
    pub fn carry_from(&self, from: &FromBus) -> Self::Lifeline;
}

Carries messages between two bus instances. A variant of the Service.

Bus types form a tree, with a 'root application' bus, and multiple busses focused on particular domains. This structure provides isolation, and predictable failures when Services spawn.

- MainBus
  | ListenerBus
  |  | ConnectionBus
  | DomainSpecificBus
  |  | ...

This trait can be implemented to carry messages between the root and the leaf of the tree.

Example

use lifeline::prelude::*;
use tokio::sync::mpsc;
lifeline_bus!(pub struct MainBus);
lifeline_bus!(pub struct LeafBus);

#[derive(Debug, Clone)]
struct LeafShutdown {}

#[derive(Debug, Clone)]
struct MainShutdown {}

impl Message<LeafBus> for LeafShutdown {
    type Channel = mpsc::Sender<Self>;   
}

impl Message<MainBus> for MainShutdown {
    type Channel = mpsc::Sender<Self>;   
}

pub struct LeafMainCarrier {
   _forward_shutdown: Lifeline
}

impl CarryFrom<MainBus> for LeafBus {
    type Lifeline = anyhow::Result<LeafMainCarrier>;
    fn carry_from(&self, from: &MainBus) -> Self::Lifeline {
        let mut rx = self.rx::<LeafShutdown>()?;
        let mut tx = from.tx::<MainShutdown>()?;

        let _forward_shutdown = Self::try_task("forward_shutdown", async move {
            if let Some(msg) = rx.recv().await {
                tx.send(MainShutdown{}).await?;
            }

            Ok(())
        });

        Ok(LeafMainCarrier { _forward_shutdown })
    }
}

Associated Types

type Lifeline[src]

The carrier lifeline. When dropped, all spawned tasks are immediately cancelled.

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Required methods

pub fn carry_from(&self, from: &FromBus) -> Self::Lifeline[src]

Spawns the carrier service, returning the lifeline value.

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Implementors

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