use ref for new_from_parent; test that transactions don't leak to parent

src/bank.rs

@@ -117,10 +117,10 @@ impl Bank {
         bank
     }
 
-    pub fn new_from_parent(parent: Arc<Bank>) -> Self {
+    pub fn new_from_parent(parent: &Arc<Bank>) -> Self {
         let mut bank = Self::default();
         bank.last_id_queue = RwLock::new(parent.last_id_queue.read().unwrap().clone());
-        bank.parent = Some(parent);
+        bank.parent = Some(parent.clone());
         bank
     }
 
@@ -1097,7 +1097,7 @@ mod tests {
         let (genesis_block, _) = GenesisBlock::new(1);
         let parent = Arc::new(Bank::new(&genesis_block));
 
-        let bank = Bank::new_from_parent(parent.clone());
+        let bank = Bank::new_from_parent(&parent);
         assert!(Arc::ptr_eq(&bank.parents()[0], &parent));
     }
 
@@ -1116,7 +1116,7 @@ mod tests {
             0,
         );
         assert_eq!(parent.process_transaction(&tx), Ok(()));
-        let bank = Bank::new_from_parent(parent);
+        let bank = Bank::new_from_parent(&parent);
         assert_eq!(
             bank.process_transaction(&tx),
             Err(BankError::DuplicateSignature)
@@ -1139,9 +1139,10 @@ mod tests {
             0,
         );
         assert_eq!(parent.process_transaction(&tx), Ok(()));
-        let bank = Bank::new_from_parent(parent);
+        let bank = Bank::new_from_parent(&parent);
         let tx = SystemTransaction::new_move(&key1, key2.pubkey(), 1, genesis_block.last_id(), 0);
         assert_eq!(bank.process_transaction(&tx), Ok(()));
+        assert_eq!(parent.get_signature_status(&tx.signatures[0]), None);
     }
 
 }

src/bank_forks.rs

@@ -64,7 +64,7 @@ mod tests {
         let bank = Bank::default();
         let finalized_bank_id = bank.tick_height();
         let mut bank_forks = BankForks::new(bank);
-        let child_bank = Bank::new_from_parent(bank_forks.working_bank());
+        let child_bank = Bank::new_from_parent(&bank_forks.working_bank());
         child_bank.register_tick(&Hash::default());
         let child_bank_id = bank_forks.insert(child_bank);
         bank_forks.set_working_bank_id(child_bank_id);

src/fullnode.rs

@@ -363,7 +363,7 @@ impl Fullnode {
                 }
                 None => FullnodeReturnType::LeaderToLeaderRotation, // value doesn't matter here...
             };
-            let tpu_bank = Arc::new(Bank::new_from_parent(self.bank.clone()));
+            let tpu_bank = Arc::new(Bank::new_from_parent(&self.bank));
             self.node_services.tpu.switch_to_leader(
                 &tpu_bank,
                 PohServiceConfig::default(),