From 89531c3aaf31450a666f4f009e782560febf0c22 Mon Sep 17 00:00:00 2001
From: yukang <moorekang@gmail.com>
Date: Mon, 23 Oct 2023 10:50:21 +0800
Subject: [PATCH] add comments

---
 tx-pool/src/process.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tx-pool/src/process.rs b/tx-pool/src/process.rs
index 80ff1262c62..61d303b0990 100644
--- a/tx-pool/src/process.rs
+++ b/tx-pool/src/process.rs
@@ -475,7 +475,7 @@ impl TxPoolService {
         let orphan = self.orphan.read().await;
         let ids = orphan.find_by_previous(tx);
         ids.iter()
-            .map(|id| orphan.get(id).cloned().unwrap())
+            .filter_map(|id| orphan.get(id).cloned())
             .collect::<Vec<_>>()
     }
 
@@ -483,6 +483,9 @@ impl TxPoolService {
         self.orphan.write().await.remove_orphan_tx(id);
     }
 
+    /// Remove all orphans which are resolved by the given transaction
+    /// the process is like a breath first search, if there is a cycle in `orphan_queue`,
+    /// `_process_tx` will return `Reject` since we have checked duplicated tx
     pub(crate) async fn process_orphan_tx(&self, tx: &TransactionView) {
         let mut orphan_queue: VecDeque<TransactionView> = VecDeque::new();
         orphan_queue.push_back(tx.clone());