program-libs/batched-merkle-tree/src/rollover_state_tree.rs (1)

98-106: 🧹 Nitpick | 🔵 Trivial

Consider moving this check before rollover_batched_state_tree to fail fast.

In the address-tree file, you moved the balance gate before loading/mutating the old tree (line 22 of rollover_address_tree.rs). Here, the rent values (merkle_tree_rent, queue_rent, additional_bytes_rent) are all known by line 79 — well before the rollover call on line 99. Moving the check earlier would short-circuit the transaction sooner, saving compute units on the unhappy path and keeping the two rollover functions structurally consistent.

Suggested reorder

+    let reimbursement_for_rent = merkle_tree_rent + queue_rent + additional_bytes_rent;
+    // 5. Check that queue account has sufficient balance for rollover.
+    #[cfg(target_os = "solana")]
+    if old_output_queue.lamports() < reimbursement_for_rent.saturating_add(queue_rent) {
+        return Err(MerkleTreeMetadataError::NotReadyForRollover.into());
+    }
+
     let new_mt_data = &mut new_state_merkle_tree.try_borrow_mut_data()?;
     let params = RolloverBatchStateTreeParams {
         ...
     };
 
-    // 5. Rollover the old Merkle tree and queue to new Merkle tree and queue.
+    // 6. Rollover the old Merkle tree and queue to new Merkle tree and queue.
     rollover_batched_state_tree(params)?;
-    let reimbursement_for_rent = merkle_tree_rent + queue_rent + additional_bytes_rent;
-    // 6. Check that queue account is rent exempt post rollover.
-    #[cfg(target_os = "solana")]
-    if old_output_queue.lamports() < reimbursement_for_rent.saturating_add(queue_rent) {
-        return Err(MerkleTreeMetadataError::NotReadyForRollover.into());
-    }
     Ok(reimbursement_for_rent)