feat: add leader_status for RegionRoute (#2670)

src/cmd/src/cli/bench.rs

@@ -157,6 +157,7 @@ fn create_region_routes() -> Vec<RegionRoute> {
                 addr: String::new(),
             }),
             follower_peers: vec![],
+            leader_status: None,
         });
     }
 

src/common/meta/src/key.rs

@@ -783,6 +783,7 @@ mod tests {
             },
             leader_peer: Some(Peer::new(datanode, "a2")),
             follower_peers: vec![],
+            leader_status: None,
         }
     }
 

src/common/meta/src/rpc/router.rs

@@ -148,6 +148,7 @@ impl TableRoute {
                 region,
                 leader_peer,
                 follower_peers,
+                leader_status: None,
             });
         }
 
@@ -196,6 +197,45 @@ pub struct RegionRoute {
     pub region: Region,
     pub leader_peer: Option<Peer>,
     pub follower_peers: Vec<Peer>,
+    /// `None` by default.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub leader_status: Option<RegionStatus>,
+}
+
+/// The Status of the [Region].
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
+pub enum RegionStatus {
+    /// The following cases in which the [Region] will be downgraded.
+    ///
+    /// - The [Region] is unavailable(e.g., Crashed, Network disconnected).
+    /// - The [Region] was planned to migrate to another [Peer].
+    Downgraded,
+}
+
+impl RegionRoute {
+    /// Returns true if the Leader [Region] is downgraded.
+    ///
+    /// The following cases in which the [Region] will be downgraded.
+    ///
+    /// - The [Region] is unavailable(e.g., Crashed, Network disconnected).
+    /// - The [Region] was planned to migrate to another [Peer].
+    ///
+    pub fn is_leader_downgraded(&self) -> bool {
+        matches!(self.leader_status, Some(RegionStatus::Downgraded))
+    }
+
+    /// Marks the Leader [Region] as downgraded.
+    ///
+    /// We should downgrade a [Region] before deactivating it:
+    ///
+    /// - During the [Region] Failover Procedure.
+    /// - Migrating a [Region].
+    ///
+    /// **Notes:** Meta Server will stop renewing the lease for the downgraded [Region].
+    ///
+    pub fn downgrade_leader(&mut self) {
+        self.leader_status = Some(RegionStatus::Downgraded)
+    }
 }
 
 pub struct RegionRoutes(pub Vec<RegionRoute>);
@@ -311,6 +351,48 @@ impl From<PbPartition> for Partition {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_leader_is_downgraded() {
+        let mut region_route = RegionRoute {
+            region: Region {
+                id: 2.into(),
+                name: "r2".to_string(),
+                partition: None,
+                attrs: BTreeMap::new(),
+            },
+            leader_peer: Some(Peer::new(1, "a1")),
+            follower_peers: vec![Peer::new(2, "a2"), Peer::new(3, "a3")],
+            leader_status: None,
+        };
+
+        assert!(!region_route.is_leader_downgraded());
+
+        region_route.downgrade_leader();
+
+        assert!(region_route.is_leader_downgraded());
+    }
+
+    #[test]
+    fn test_region_route_decode() {
+        let region_route = RegionRoute {
+            region: Region {
+                id: 2.into(),
+                name: "r2".to_string(),
+                partition: None,
+                attrs: BTreeMap::new(),
+            },
+            leader_peer: Some(Peer::new(1, "a1")),
+            follower_peers: vec![Peer::new(2, "a2"), Peer::new(3, "a3")],
+            leader_status: None,
+        };
+
+        let input = r#"{"region":{"id":2,"name":"r2","partition":null,"attrs":{}},"leader_peer":{"id":1,"addr":"a1"},"follower_peers":[{"id":2,"addr":"a2"},{"id":3,"addr":"a3"}]}"#;
+
+        let decoded: RegionRoute = serde_json::from_str(input).unwrap();
+
+        assert_eq!(decoded, region_route);
+    }
+
     #[test]
     fn test_de_serialize_partition() {
         let p = Partition {

src/frontend/src/instance/standalone.rs

@@ -128,6 +128,7 @@ impl TableMetadataAllocator for StandaloneTableMetadataCreator {
                     region,
                     leader_peer: Some(peer),
                     follower_peers: vec![],
+                    leader_status: None,
                 }
             })
             .collect::<Vec<_>>();

src/meta-srv/src/table_meta_alloc.rs

@@ -118,6 +118,7 @@ async fn handle_create_region_routes(
                 region,
                 leader_peer: Some(peer.into()),
                 follower_peers: vec![], // follower_peers is not supported at the moment
+                leader_status: None,
             }
         })
         .collect::<Vec<_>>();

src/meta-srv/src/test_util.rs

@@ -48,6 +48,7 @@ pub(crate) fn new_region_route(region_id: u64, peers: &[Peer], leader_node: u64)
         region,
         leader_peer,
         follower_peers: vec![],
+        leader_status: None,
     }
 }
 
@@ -133,6 +134,7 @@ pub(crate) async fn prepare_table_region_and_info_value(
             addr: String::new(),
         }),
         follower_peers: vec![],
+        leader_status: None,
     };
 
     // Region distribution:

src/operator/src/tests/partition_manager.rs

@@ -122,6 +122,7 @@ pub(crate) async fn create_partition_rule_manager(
                     },
                     leader_peer: Some(Peer::new(3, "")),
                     follower_peers: vec![],
+                    leader_status: None,
                 },
                 RegionRoute {
                     region: Region {
@@ -139,6 +140,7 @@ pub(crate) async fn create_partition_rule_manager(
                     },
                     leader_peer: Some(Peer::new(2, "")),
                     follower_peers: vec![],
+                    leader_status: None,
                 },
                 RegionRoute {
                     region: Region {
@@ -156,6 +158,7 @@ pub(crate) async fn create_partition_rule_manager(
                     },
                     leader_peer: Some(Peer::new(1, "")),
                     follower_peers: vec![],
+                    leader_status: None,
                 },
             ],
         )
@@ -185,6 +188,7 @@ pub(crate) async fn create_partition_rule_manager(
                     },
                     leader_peer: None,
                     follower_peers: vec![],
+                    leader_status: None,
                 },
                 RegionRoute {
                     region: Region {
@@ -205,6 +209,7 @@ pub(crate) async fn create_partition_rule_manager(
                     },
                     leader_peer: None,
                     follower_peers: vec![],
+                    leader_status: None,
                 },
                 RegionRoute {
                     region: Region {
@@ -222,6 +227,7 @@ pub(crate) async fn create_partition_rule_manager(
                     },
                     leader_peer: None,
                     follower_peers: vec![],
+                    leader_status: None,
                 },
             ],
         )