feat(txpool): add is_transaction_ready to TransactionPool trait (#21742)

Co-authored-by: Matthias Seitz <matthias.seitz@outlook.de>
Co-authored-by: Amp <amp@ampcode.com>

crates/transaction-pool/src/lib.rs

@@ -610,6 +610,14 @@ where
         self.pool.pending_transactions()
     }
 
+    fn get_pending_transaction_by_sender_and_nonce(
+        &self,
+        sender: Address,
+        nonce: u64,
+    ) -> Option<Arc<ValidPoolTransaction<Self::Transaction>>> {
+        self.pool.get_pending_transaction_by_sender_and_nonce(sender, nonce)
+    }
+
     fn pending_transactions_max(
         &self,
         max: usize,

crates/transaction-pool/src/pool/mod.rs

@@ -1090,6 +1090,16 @@ where
         self.get_pool_data().get_transactions_by_sender(sender_id)
     }
 
+    /// Returns a pending transaction sent by the given sender with the given nonce.
+    pub fn get_pending_transaction_by_sender_and_nonce(
+        &self,
+        sender: Address,
+        nonce: u64,
+    ) -> Option<Arc<ValidPoolTransaction<T::Transaction>>> {
+        let sender_id = self.get_sender_id(sender);
+        self.get_pool_data().get_pending_transaction_by_sender_and_nonce(sender_id, nonce)
+    }
+
     /// Returns all queued transactions of the address by sender
     pub fn get_queued_transactions_by_sender(
         &self,

crates/transaction-pool/src/pool/txpool.rs

@@ -560,6 +560,18 @@ impl<T: TransactionOrdering> TxPool<T> {
         self.all_transactions.txs_iter(sender).map(|(_, tx)| Arc::clone(&tx.transaction)).collect()
     }
 
+    /// Returns a pending transaction sent by the given sender with the given nonce.
+    pub(crate) fn get_pending_transaction_by_sender_and_nonce(
+        &self,
+        sender: SenderId,
+        nonce: u64,
+    ) -> Option<Arc<ValidPoolTransaction<T::Transaction>>> {
+        self.all_transactions
+            .txs_iter(sender)
+            .find(|(id, tx)| id.nonce == nonce && tx.subpool == SubPool::Pending)
+            .map(|(_, tx)| Arc::clone(&tx.transaction))
+    }
+
     /// Updates only the pending fees without triggering subpool updates.
     /// Returns the previous base fee and blob fee values.
     const fn update_pending_fees_only(

crates/transaction-pool/src/traits.rs

@@ -405,6 +405,16 @@ pub trait TransactionPool: Clone + Debug + Send + Sync {
     /// Consumer: RPC
     fn pending_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;
 
+    /// Returns a pending transaction if it exists and is ready for immediate execution
+    /// (i.e., has the lowest nonce among the sender's pending transactions).
+    fn get_pending_transaction_by_sender_and_nonce(
+        &self,
+        sender: Address,
+        nonce: u64,
+    ) -> Option<Arc<ValidPoolTransaction<Self::Transaction>>> {
+        self.best_transactions().find(|tx| tx.sender() == sender && tx.nonce() == nonce)
+    }
+
     /// Returns first `max` transactions that can be included in the next block.
     /// See <https://github.com/paradigmxyz/reth/issues/12767#issuecomment-2493223579>
     ///