feat: add staging area

crates/mempool/src/mempool.rs

@@ -1,5 +1,5 @@
 use std::collections::hash_map::Entry::{Occupied, Vacant};
-use std::collections::{BTreeMap, HashMap};
+use std::collections::{BTreeMap, BTreeSet, HashMap};
 
 use anyhow::Result;
 use mempool_infra::network_component::CommunicationInterface;
@@ -25,6 +25,7 @@ pub struct Mempool {
     txs_queue: TransactionPriorityQueue,
     tx_store: HashMap<ContractAddress, BTreeMap<Nonce, ThinTransaction>>,
     tx_hash_2_tx: HashMap<TransactionHash, ThinTransaction>,
+    staging: BTreeSet<TransactionHash>,
     state: HashMap<ContractAddress, AccountState>,
 }
 
@@ -39,6 +40,7 @@ impl Mempool {
             tx_store: HashMap::default(),
             state: HashMap::default(),
             tx_hash_2_tx: HashMap::default(),
+            staging: BTreeSet::default(),
             gateway_network,
             batcher_network,
         };
@@ -87,6 +89,7 @@ impl Mempool {
 
         let mut txs: Vec<ThinTransaction> = Vec::default();
         for pq_tx in &pq_txs {
+            self.staging.insert(pq_tx.tx_hash);
             let tx = self.tx_hash_2_tx.remove(&pq_tx.tx_hash).unwrap();
             self.state.remove(&tx.sender_address);
             self.tx_store.remove(&tx.sender_address);