Change: Membership.nodes remove Option from value

Before this commit, the value of `Membership.nodes` is `Option<N:
Node>`: `Membership.nodes: BTreeMap<NID, Option<N>>`

The value does not have to be an `Option`.
If an application does not need openraft to store the `Node` data, it
can just implement `trait Node` with an empty struct, or just use
`BasicNode` as a placeholder.

- Using `Option<N>` as the value is a legacy and since #480 is merged, we
  do not need the `Option` any more.

examples/raft-kv-memstore/src/network/management.rs

@@ -28,7 +28,7 @@ pub async fn add_learner(
 ) -> actix_web::Result<impl Responder> {
     let node_id = req.0 .0;
     let node = BasicNode { addr: req.0 .1.clone() };
-    let res = app.raft.add_learner(node_id, Some(node), true).await;
+    let res = app.raft.add_learner(node_id, node, true).await;
     Ok(Json(res))
 }
 

examples/raft-kv-memstore/src/network/raft_network_impl.rs

@@ -26,7 +26,7 @@ impl ExampleNetwork {
     pub async fn send_rpc<Req, Resp, Err>(
         &self,
         target: ExampleNodeId,
-        target_node: Option<&BasicNode>,
+        target_node: &BasicNode,
         uri: &str,
         req: Req,
     ) -> Result<Resp, RPCError<ExampleNodeId, BasicNode, Err>>
@@ -35,7 +35,7 @@ impl ExampleNetwork {
         Err: std::error::Error + DeserializeOwned,
         Resp: DeserializeOwned,
     {
-        let addr = target_node.map(|x| &x.addr).unwrap();
+        let addr = &target_node.addr;
 
         let url = format!("http://{}/{}", addr, uri);
         let client = reqwest::Client::new();
@@ -57,20 +57,20 @@ impl RaftNetworkFactory<ExampleTypeConfig> for ExampleNetwork {
     async fn connect(
         &mut self,
         target: ExampleNodeId,
-        node: Option<&BasicNode>,
+        node: &BasicNode,
     ) -> Result<Self::Network, Self::ConnectionError> {
         Ok(ExampleNetworkConnection {
             owner: ExampleNetwork {},
             target,
-            target_node: node.cloned(),
+            target_node: node.clone(),
         })
     }
 }
 
 pub struct ExampleNetworkConnection {
     owner: ExampleNetwork,
     target: ExampleNodeId,
-    target_node: Option<BasicNode>,
+    target_node: BasicNode,
 }
 
 #[async_trait]
@@ -82,7 +82,7 @@ impl RaftNetwork<ExampleTypeConfig> for ExampleNetworkConnection {
         AppendEntriesResponse<ExampleNodeId>,
         RPCError<ExampleNodeId, BasicNode, AppendEntriesError<ExampleNodeId>>,
     > {
-        self.owner.send_rpc(self.target, self.target_node.as_ref(), "raft-append", req).await
+        self.owner.send_rpc(self.target, &self.target_node, "raft-append", req).await
     }
 
     async fn send_install_snapshot(
@@ -92,13 +92,13 @@ impl RaftNetwork<ExampleTypeConfig> for ExampleNetworkConnection {
         InstallSnapshotResponse<ExampleNodeId>,
         RPCError<ExampleNodeId, BasicNode, InstallSnapshotError<ExampleNodeId>>,
     > {
-        self.owner.send_rpc(self.target, self.target_node.as_ref(), "raft-snapshot", req).await
+        self.owner.send_rpc(self.target, &self.target_node, "raft-snapshot", req).await
     }
 
     async fn send_vote(
         &mut self,
         req: VoteRequest<ExampleNodeId>,
     ) -> Result<VoteResponse<ExampleNodeId>, RPCError<ExampleNodeId, BasicNode, VoteError<ExampleNodeId>>> {
-        self.owner.send_rpc(self.target, self.target_node.as_ref(), "raft-vote", req).await
+        self.owner.send_rpc(self.target, &self.target_node, "raft-vote", req).await
     }
 }

examples/raft-kv-memstore/tests/cluster/test_cluster.rs

@@ -90,9 +90,9 @@ async fn test_cluster() -> anyhow::Result<()> {
         x.membership_config.nodes().map(|(nid, node)| (*nid, node.clone())).collect::<BTreeMap<_, _>>();
     assert_eq!(
         btreemap! {
-            1 => Some(BasicNode::new("127.0.0.1:21001")),
-            2 => Some(BasicNode::new("127.0.0.1:21002")),
-            3 => Some(BasicNode::new("127.0.0.1:21003")),
+            1 => BasicNode::new("127.0.0.1:21001"),
+            2 => BasicNode::new("127.0.0.1:21002"),
+            3 => BasicNode::new("127.0.0.1:21003"),
         },
         nodes_in_cluster
     );

examples/raft-kv-rocksdb/src/network/management.rs

@@ -32,7 +32,7 @@ pub fn rest(app: &mut Server) {
 async fn add_learner(mut req: Request<Arc<ExampleApp>>) -> tide::Result {
     let (node_id, api_addr, rpc_addr): (ExampleNodeId, String, String) = req.body_json().await?;
     let node = ExampleNode { rpc_addr, api_addr };
-    let res = req.state().raft.add_learner(node_id, Some(node), true).await;
+    let res = req.state().raft.add_learner(node_id, node, true).await;
     Ok(Response::builder(StatusCode::Ok).body(Body::from_json(&res)?).build())
 }
 

examples/raft-kv-rocksdb/src/network/raft_network_impl.rs

@@ -68,10 +68,10 @@ impl RaftNetworkFactory<ExampleTypeConfig> for ExampleNetwork {
     async fn connect(
         &mut self,
         target: ExampleNodeId,
-        node: Option<&ExampleNode>,
+        node: &ExampleNode,
     ) -> Result<Self::Network, Self::ConnectionError> {
         dbg!(&node);
-        let addr = node.map(|x| format!("ws://{}", x.rpc_addr)).unwrap();
+        let addr = format!("ws://{}", node.rpc_addr);
         let client = Client::dial_websocket(&addr).await.ok();
         Ok(ExampleNetworkConnection { addr, client, target })
     }

examples/raft-kv-rocksdb/tests/cluster/test_cluster.rs

@@ -91,9 +91,9 @@ async fn test_cluster() -> Result<(), Box<dyn std::error::Error>> {
         x.membership_config.nodes().map(|(nid, node)| (*nid, node.clone())).collect::<BTreeMap<_, _>>();
     assert_eq!(
         btreemap! {
-            1 => Some(ExampleNode{rpc_addr: get_rpc_addr(1), api_addr: get_addr(1)}),
-            2 => Some(ExampleNode{rpc_addr: get_rpc_addr(2), api_addr: get_addr(2)}),
-            3 => Some(ExampleNode{rpc_addr: get_rpc_addr(3), api_addr: get_addr(3)}),
+            1 => ExampleNode{rpc_addr: get_rpc_addr(1), api_addr: get_addr(1)},
+            2 => ExampleNode{rpc_addr: get_rpc_addr(2), api_addr: get_addr(2)},
+            3 => ExampleNode{rpc_addr: get_rpc_addr(3), api_addr: get_addr(3)},
         },
         nodes_in_cluster
     );

openraft/src/core/raft_core.rs

@@ -380,8 +380,8 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
             };
 
             let my_id = self.id;
-            let target_node = self.engine.state.membership_state.effective.get_node(&target).cloned();
-            let mut network = match self.network.connect(target, target_node.as_ref()).await {
+            let target_node = self.engine.state.membership_state.effective.get_node(&target).clone();
+            let mut network = match self.network.connect(target, &target_node).await {
                 Ok(n) => n,
                 Err(e) => {
                     tracing::error!(target = display(target), "{}", e);
@@ -479,7 +479,7 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
     pub(super) async fn add_learner(
         &mut self,
         target: C::NodeId,
-        node: Option<C::Node>,
+        node: C::Node,
         tx: RaftAddLearnerTx<C::NodeId, C::Node>,
     ) -> Result<(), Fatal<C::NodeId>> {
         if let Some(l) = &self.leader_data {
@@ -517,7 +517,7 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
         }
 
         // Ensure the node is connectable
-        let conn_res = self.network.connect(target, node.clone().as_ref()).await;
+        let conn_res = self.network.connect(target, &node).await;
         if let Err(e) = conn_res {
             let net_err = NetworkError::new(&anyerror::AnyError::new(&e));
             let _ = tx.send(Err(AddLearnerError::NetworkError(net_err)));
@@ -780,9 +780,9 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
     #[tracing::instrument(level = "debug", skip(self))]
     pub(crate) async fn handle_initialize(
         &mut self,
-        member_nodes: BTreeMap<C::NodeId, Option<C::Node>>,
+        member_nodes: BTreeMap<C::NodeId, C::Node>,
     ) -> Result<(), InitializeError<C::NodeId, C::Node>> {
-        let membership = Membership::try_from(member_nodes)?;
+        let membership = Membership::from(member_nodes);
         let payload = EntryPayload::<C>::Membership(membership);
 
         let mut entry_refs = [EntryRef::new(&payload)];
@@ -967,10 +967,7 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
     }
 
     pub(crate) fn get_leader_node(&self, leader_id: Option<C::NodeId>) -> Option<C::Node> {
-        match leader_id {
-            None => None,
-            Some(id) => self.engine.state.membership_state.effective.get_node(&id).cloned(),
-        }
+        leader_id.map(|id| self.engine.state.membership_state.effective.get_node(&id).clone())
     }
 
     #[tracing::instrument(level = "debug", skip_all)]
@@ -1071,7 +1068,7 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
 
         Ok(ReplicationCore::<C, N, S>::spawn(
             target,
-            target_node.cloned(),
+            target_node.clone(),
             self.engine.state.vote,
             self.config.clone(),
             self.engine.state.last_log_id(),
@@ -1259,8 +1256,8 @@ impl<C: RaftTypeConfig, N: RaftNetworkFactory<C>, S: RaftStorage<C>> RaftCore<C,
             }
 
             let req = vote_req.clone();
-            let target_node = self.engine.state.membership_state.effective.get_node(&target).cloned();
-            let mut network = match self.network.connect(target, target_node.as_ref()).await {
+            let target_node = self.engine.state.membership_state.effective.get_node(&target).clone();
+            let mut network = match self.network.connect(target, &target_node).await {
                 Ok(n) => n,
                 Err(err) => {
                     tracing::error!({error=%err, target=display(target)}, "while requesting vote");

openraft/src/error.rs

@@ -466,6 +466,7 @@ pub struct NotAllowed<NID: NodeId> {
 #[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
 #[error("node {node_id} {reason}")]
+// TODO: remove it
 pub struct MissingNodeInfo<NID: NodeId> {
     pub node_id: NID,
     pub reason: String,

openraft/src/membership/effective_membership.rs

@@ -151,12 +151,12 @@ where
     }
 
     /// Get a the node(either voter or learner) by node id.
-    pub fn get_node(&self, node_id: &NID) -> Option<&N> {
+    pub fn get_node(&self, node_id: &NID) -> &N {
         self.membership.get_node(node_id)
     }
 
     /// Returns an Iterator of all nodes(voters and learners).
-    pub fn nodes(&self) -> impl Iterator<Item = (&NID, &Option<N>)> {
+    pub fn nodes(&self) -> impl Iterator<Item = (&NID, &N)> {
         self.membership.nodes()
     }
 

openraft/src/membership/membership.rs

@@ -14,23 +14,21 @@ use crate::quorum::QuorumSet;
 use crate::MessageSummary;
 use crate::NodeId;
 
-/// BTreeMap for mapping node-id the node.
-pub type NodeMap<NID, N> = BTreeMap<NID, Option<N>>;
 /// Convert other types into the internal data structure for node infos
 pub trait IntoOptionNodes<NID, N>
 where
     N: Node,
     NID: NodeId,
 {
-    fn into_option_nodes(self) -> NodeMap<NID, N>;
+    fn into_option_nodes(self) -> BTreeMap<NID, N>;
 }
 
 impl<NID, N> IntoOptionNodes<NID, N> for ()
 where
     N: Node,
     NID: NodeId,
 {
-    fn into_option_nodes(self) -> NodeMap<NID, N> {
+    fn into_option_nodes(self) -> BTreeMap<NID, N> {
         btreemap! {}
     }
 }
@@ -40,8 +38,8 @@ where
     N: Node,
     NID: NodeId,
 {
-    fn into_option_nodes(self) -> NodeMap<NID, N> {
-        self.into_iter().map(|node_id| (node_id, None)).collect()
+    fn into_option_nodes(self) -> BTreeMap<NID, N> {
+        self.into_iter().map(|node_id| (node_id, N::default())).collect()
     }
 }
 
@@ -50,17 +48,7 @@ where
     N: Node,
     NID: NodeId,
 {
-    fn into_option_nodes(self) -> NodeMap<NID, N> {
-        self.into_iter().map(|(node_id, n)| (node_id, Some(n))).collect()
-    }
-}
-
-impl<NID, N> IntoOptionNodes<NID, N> for NodeMap<NID, N>
-where
-    N: Node,
-    NID: NodeId,
-{
-    fn into_option_nodes(self) -> NodeMap<NID, N> {
+    fn into_option_nodes(self) -> BTreeMap<NID, N> {
         self
     }
 }
@@ -84,22 +72,19 @@ where
     /// Additional info of all nodes, e.g., the connecting host and port.
     ///
     /// A node-id key that is in `nodes` but is not in `configs` is a **learner**.
-    /// The values in this map must all be `Some` or `None`.
-    nodes: BTreeMap<NID, Option<N>>,
+    nodes: BTreeMap<NID, N>,
 }
 
-impl<NID, N> TryFrom<BTreeMap<NID, Option<N>>> for Membership<NID, N>
+impl<NID, N> From<BTreeMap<NID, N>> for Membership<NID, N>
 where
     N: Node,
     NID: NodeId,
 {
-    type Error = MissingNodeInfo<NID>;
-
-    fn try_from(b: BTreeMap<NID, Option<N>>) -> Result<Self, Self::Error> {
+    fn from(b: BTreeMap<NID, N>) -> Self {
         let member_ids = b.keys().cloned().collect::<BTreeSet<NID>>();
 
-        let membership = Membership::with_nodes(vec![member_ids], b)?;
-        Ok(membership)
+        // Safe unwrap: every node-id in `member_ids` present in `b`.
+        Membership::with_nodes(vec![member_ids], b).unwrap()
     }
 }
 
@@ -122,9 +107,8 @@ where
                 }
                 res.push(format!("{}", node_id));
 
-                if let Some(n) = self.get_node(node_id) {
-                    res.push(format!(":{{{}}}", n));
-                }
+                let n = self.get_node(node_id);
+                res.push(format!(":{{{}}}", n));
             }
             res.push("}".to_string());
         }
@@ -141,9 +125,8 @@ where
 
             res.push(format!("{}", learner_id));
 
-            if let Some(n) = self.get_node(learner_id) {
-                res.push(format!(":{{{}}}", n));
-            }
+            let n = self.get_node(learner_id);
+            res.push(format!(":{{{}}}", n));
         }
         res.push("]".to_string());
         res.join("")
@@ -194,28 +177,14 @@ where
             }
         }
 
-        let has_some = nodes.values().any(|x| x.is_some());
-        if has_some {
-            let first_none = nodes.iter().find(|(_node_id, v)| v.is_none());
-            if let Some(first_none) = first_none {
-                return Err(MissingNodeInfo {
-                    node_id: *first_none.0,
-                    reason: "is None".to_string(),
-                });
-            }
-        }
-
         Ok(Membership { configs, nodes })
     }
 
     /// Extends nodes btreemap with another.
     ///
     /// Node that present in `old` will **NOT** be replaced because changing the address of a node potentially breaks
     /// consensus guarantee.
-    pub(crate) fn extend_nodes(
-        old: BTreeMap<NID, Option<N>>,
-        new: &BTreeMap<NID, Option<N>>,
-    ) -> BTreeMap<NID, Option<N>> {
+    pub(crate) fn extend_nodes(old: BTreeMap<NID, N>, new: &BTreeMap<NID, N>) -> BTreeMap<NID, N> {
         let mut res = old;
 
         for (k, v) in new.iter() {
@@ -233,7 +202,7 @@ where
         self.configs.len() > 1
     }
 
-    pub(crate) fn add_learner(&self, node_id: NID, node: Option<N>) -> Result<Self, MissingNodeInfo<NID>> {
+    pub(crate) fn add_learner(&self, node_id: NID, node: N) -> Result<Self, MissingNodeInfo<NID>> {
         let configs = self.configs.clone();
 
         let nodes = Self::extend_nodes(self.nodes.clone(), &btreemap! {node_id=>node});
@@ -289,13 +258,12 @@ where
     }
 
     /// Get a the node(either voter or learner) by node id.
-    pub(crate) fn get_node(&self, node_id: &NID) -> Option<&N> {
-        let x = self.nodes.get(node_id)?;
-        x.as_ref()
+    pub(crate) fn get_node(&self, node_id: &NID) -> &N {
+        &self.nodes[node_id]
     }
 
     /// Returns an Iterator of all nodes(voters and learners).
-    pub fn nodes(&self) -> impl Iterator<Item = (&NID, &Option<N>)> {
+    pub fn nodes(&self) -> impl Iterator<Item = (&NID, &N)> {
         self.nodes.iter()
     }