fix #34, record abandoned reason for conflicting entry logs

little_raft/src/replica.rs

@@ -534,9 +534,16 @@ where
             return;
         }
 
+        let mut state_machine = self.state_machine.lock().unwrap();
         for entry in entries {
             // Drop local inconsistent logs.
             if entry.index < self.log.len() && entry.term != self.log[entry.index].term {
+                for i in entry.index..self.log.len() {
+                    state_machine.register_transition_state(
+                        self.log[i].transition.get_id(),
+                        TransitionState::Abandoned(TransitionAbandonedReason::ConflictingEntry)
+                    );
+                } 
                 self.log.truncate(entry.index);
             }
 

little_raft/src/state_machine.rs

@@ -26,6 +26,10 @@ pub enum TransitionAbandonedReason {
     // NotLeader transitions have been abandoned because the replica is not
     // the cluster leader.
     NotLeader,
+
+    // ConflictingEntry entry logs in followers that are inconsistent with the
+    // leader's.
+    ConflictingEntry,
 }
 
 /// StateMachineTransition describes a user-defined transition that can be