fix(txpool): queued tx ordering (#1643)

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

@@ -92,7 +92,6 @@ mod parked;
 pub(crate) mod pending;
 pub(crate) mod size;
 pub(crate) mod state;
-mod transaction;
 pub mod txpool;
 mod update;
 

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

@@ -231,8 +231,8 @@ impl<T: PoolTransaction> Ord for BasefeeOrd<T> {
 /// `Queued` transactions are transactions that are currently blocked by other parked (basefee,
 /// queued) or missing transactions.
 ///
-/// The primary order function for is always compares via the timestamp when the transaction was
-/// created
+/// The primary order function always compares the transaction costs first. In case these
+/// are equal, it compares the timestamps when the transactions were created.
 #[derive(Debug)]
 pub(crate) struct QueuedOrd<T: PoolTransaction>(Arc<ValidPoolTransaction<T>>);
 
@@ -240,6 +240,9 @@ impl_ord_wrapper!(QueuedOrd);
 
 impl<T: PoolTransaction> Ord for QueuedOrd<T> {
     fn cmp(&self, other: &Self) -> Ordering {
-        other.timestamp.cmp(&self.timestamp)
+        // Higher cost is better
+        self.cost.cmp(&other.cost).then_with(||
+            // Lower timestamp is better
+            other.timestamp.cmp(&self.timestamp))
     }
 }

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

@@ -1 +0,0 @@
-