Is there a way to get the list of all nodes?

[l-7-l]

I’m building a delayed message scheduling service.
d_engine is responsible for leader election and maintaining shard assignments for nodes.

When the leader changes, the new leader needs to check whether the cluster membership has changed (i.e., nodes added or removed). If the number of nodes has changed, the shards need to be rebalanced.

[l-7-l]

Founded: https://docs.rs/d-engine/latest/d_engine/trait.ClientApi.html#tymethod.list_members
If you have any suggestions for building a delayed message scheduling service, feel free to share.

[JoshuaChi]

Two patterns depending on your deployment mode:

Embedded mode — live query, no refresh needed:

// Subscribe first to avoid missing changes during election
let mut rx = engine.leader_change_notifier();
engine.wait_ready(Duration::from_secs(5)).await?;

// list_members() sends a live query to Raft core — always current
let members = engine.client().list_members().await?;

// React to future leader changes
while rx.changed().await.is_ok() {
    if let Some(info) = *rx.borrow() {
        if info.leader_id == engine.node_id() {
            let members = engine.client().list_members().await?;
            rebalance_shards(members);
        }
    }
}

Note: requires features = ["client"] in Cargo.toml

Standalone/gRPC mode — cached data, must refresh first:

// list_members() returns cached pool data — call refresh() first
client.refresh(None).await?;
let members = client.list_members().await?;

Both APIs are available in v0.2.3.

[l-7-l]

Yes, thank you. I’m now using the approach you mentioned with leader_change_notifier. When the leader changes, I retrieve the list of nodes(engine.client.list_members) to check whether shard reassignment is needed .

    pub async fn on_leader_change(&self, actor: ActorRef<Self>) {
        let mut rx = self.engine.leader_change_notifier();
        let node_id = self.node_id;
        let mut is_leader = self.is_leader;

        tokio::spawn(async move {
            while rx.changed().await.is_ok() {
                let now_is_leader = rx.borrow().as_ref().is_some_and(|x| x.leader_id == node_id);
                if is_leader == now_is_leader {
                    continue;
                }

                if actor.tell(LeaderChanged).await.is_ok() {
                    is_leader = now_is_leader;
                }
            }
        });
    }
}

Thanks again. This looks like an ambitious project—keep up the great work! Wishing you continued success. 🚀