refactor: MemStore by default turns on defensive check

async-raft/src/core/append_entries.rs

@@ -38,6 +38,7 @@ impl<D: AppData, R: AppDataResponse, N: RaftNetwork<D>, S: RaftStorage<D, R>> Ra
         }
 
         // Update election timeout.
+        // TODO(xp): only update commit_index if the log present. e.g., append entries first, then update commit_index.
         self.update_next_election_timeout(true);
         let mut report_metrics = false;
         self.commit_index = msg.leader_commit; // The value for `self.commit_index` is only updated here when not the leader.

memstore/src/lib.rs

@@ -110,7 +110,7 @@ impl MemStore {
         let hs = RwLock::new(None);
         let current_snapshot = RwLock::new(None);
         Self {
-            defensive: RwLock::new(false),
+            defensive: RwLock::new(true),
             id,
             log,
             sm,
@@ -134,7 +134,7 @@ impl MemStore {
         let hs = RwLock::new(hs);
         let current_snapshot = RwLock::new(current_snapshot);
         Self {
-            defensive: RwLock::new(false),
+            defensive: RwLock::new(true),
             id,
             log,
             sm,
@@ -179,8 +179,13 @@ impl MemStore {
             return Err(anyhow::anyhow!("smaller term is now allowed"));
         }
 
-        if hs.current_term == curr.current_term && hs.voted_for != curr.voted_for {
-            return Err(anyhow::anyhow!("voted_for can not change in one term"));
+        if hs.current_term == curr.current_term && curr.voted_for.is_some() && hs.voted_for != curr.voted_for {
+            return Err(anyhow::anyhow!(
+                "voted_for can not change in one term({}) curr: {:?} change to {:?}",
+                hs.current_term,
+                curr.voted_for,
+                hs.voted_for
+            ));
         }
 
         Ok(())

memstore/src/test.rs

@@ -25,7 +25,9 @@ struct MemStoreBuilder {}
 #[async_trait]
 impl StoreBuilder<ClientRequest, ClientResponse, MemStore> for MemStoreBuilder {
     async fn new_store(&self, id: NodeId) -> MemStore {
-        MemStore::new(id)
+        let sto = MemStore::new(id);
+        sto.defensive(false).await;
+        sto
     }
 }