From 74bdba46134d9404447e6b92df6fee75610de148 Mon Sep 17 00:00:00 2001
From: Weny Xu <wenymedia@gmail.com>
Date: Fri, 18 Oct 2024 14:26:41 +0800
Subject: [PATCH] fix: fix metadata forward compatibility issue (#4846)

---
 src/common/meta/src/rpc/router.rs | 68 +++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/src/common/meta/src/rpc/router.rs b/src/common/meta/src/rpc/router.rs
index 8dc409c8be..dd7349ae8f 100644
--- a/src/common/meta/src/rpc/router.rs
+++ b/src/common/meta/src/rpc/router.rs
@@ -289,6 +289,7 @@ pub enum LeaderState {
     ///
     /// - The [`Region`] may be unavailable (e.g., Crashed, Network disconnected).
     /// - The [`Region`] was planned to migrate to another [`Peer`].
+    #[serde(alias = "Downgraded")]
     Downgrading,
 }
 
@@ -516,6 +517,73 @@ mod tests {
         assert_eq!(decoded, region_route);
     }
 
+    #[test]
+    fn test_region_route_compatibility() {
+        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_state: Some(LeaderState::Downgrading),
+            leader_down_since: 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"}],"leader_state":"Downgraded","leader_down_since":null}"#;
+        let decoded: RegionRoute = serde_json::from_str(input).unwrap();
+        assert_eq!(decoded, region_route);
+
+        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_state: Some(LeaderState::Downgrading),
+            leader_down_since: 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"}],"leader_status":"Downgraded","leader_down_since":null}"#;
+        let decoded: RegionRoute = serde_json::from_str(input).unwrap();
+        assert_eq!(decoded, region_route);
+
+        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_state: Some(LeaderState::Downgrading),
+            leader_down_since: 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"}],"leader_state":"Downgrading","leader_down_since":null}"#;
+        let decoded: RegionRoute = serde_json::from_str(input).unwrap();
+        assert_eq!(decoded, region_route);
+
+        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_state: Some(LeaderState::Downgrading),
+            leader_down_since: 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"}],"leader_status":"Downgrading","leader_down_since":null}"#;
+        let decoded: RegionRoute = serde_json::from_str(input).unwrap();
+        assert_eq!(decoded, region_route);
+    }
+
     #[test]
     fn test_de_serialize_partition() {
         let p = Partition {