fix(meta): ignore legacy StateMachineId during V004 upgrade

# Summary

Drop obsolete V003 StateMachineId raft-state entries while upgrading to the V004 raft log format so old meta data can start without hitting the V004 importer panic.

# Details

StateMachineId has no V004 raft-log representation and should not be forwarded as a V003 RaftStateKV. The upgrade path now models dropped entries explicitly with None and skips them in both V003 import loops.

Verified with a v1.2.292 debug fixture containing a legacy StateMachineId row: unpatched v1.2.768 panicked at the V004 importer, while the patched debug build upgraded to V004 and started successfully.

Author: drmingdrmer

src/meta/raft-store/src/key_spaces.rs

@@ -253,16 +253,16 @@ pub enum RaftStoreEntry {
 
 impl RaftStoreEntry {
     /// Upgrade V003 to V004
-    pub fn upgrade(self) -> Self {
+    pub fn upgrade(self) -> Option<Self> {
         match self.clone() {
-            Self::Logs { key: _, value } => Self::LogEntry(value),
+            Self::Logs { key: _, value } => Some(Self::LogEntry(value)),
             Self::RaftStateKV { key: _, value } => match value {
-                RaftStateValue::NodeId(node_id) => Self::NodeId(Some(node_id)),
-                RaftStateValue::HardState(vote) => Self::Vote(Some(vote)),
-                RaftStateValue::Committed(committed) => Self::Committed(committed),
-                RaftStateValue::StateMachineId(_) => self,
+                RaftStateValue::NodeId(node_id) => Some(Self::NodeId(Some(node_id))),
+                RaftStateValue::HardState(vote) => Some(Self::Vote(Some(vote))),
+                RaftStateValue::Committed(committed) => Some(Self::Committed(committed)),
+                RaftStateValue::StateMachineId(_) => None,
             },
-            Self::LogMeta { key: _, value } => Self::Purged(Some(value.log_id())),
+            Self::LogMeta { key: _, value } => Some(Self::Purged(Some(value.log_id()))),
 
             RaftStoreEntry::DataHeader { .. }
             | RaftStoreEntry::Nodes { .. }
@@ -275,7 +275,7 @@ impl RaftStoreEntry {
             | RaftStoreEntry::NodeId(_)
             | RaftStoreEntry::Vote(_)
             | RaftStoreEntry::Committed(_)
-            | RaftStoreEntry::Purged(_) => self,
+            | RaftStoreEntry::Purged(_) => Some(self),
         }
     }
 

src/meta/raft-store/src/ondisk/upgrade_to_v004.rs

@@ -89,7 +89,9 @@ impl OnDisk {
                 })?;
 
                 let ent = RaftStoreEntry::deserialize(&k, &v)?;
-                let upgraded = ent.upgrade();
+                let Some(upgraded) = ent.upgrade() else {
+                    continue;
+                };
                 if let RaftStoreEntry::LogEntry(entry) = &upgraded {
                     if entry.log_id.index < first_log_index {
                         debug!(
@@ -116,7 +118,9 @@ impl OnDisk {
             for kv in kvs {
                 let ent = RaftStoreEntry::deserialize(&kv[0], &kv[1])?;
                 debug!("import V003 entry: {:?}", ent);
-                let upgraded = ent.upgrade();
+                let Some(upgraded) = ent.upgrade() else {
+                    continue;
+                };
                 importer.import_raft_store_entry(upgraded)?;
             }
         }