feat: provide a way to opt out of pool updates (#4270)

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

@@ -25,6 +25,10 @@ impl<T: TransactionOrdering> crate::traits::BestTransactions for BestTransaction
     fn mark_invalid(&mut self, tx: &Self::Item) {
         BestTransactions::mark_invalid(&mut self.best, tx)
     }
+
+    fn no_updates(&mut self) {
+        self.best.no_updates()
+    }
 }
 
 impl<T: TransactionOrdering> Iterator for BestTransactionsWithBasefee<T> {
@@ -67,7 +71,7 @@ pub(crate) struct BestTransactions<T: TransactionOrdering> {
     ///
     /// These new pending transactions are inserted into this iterator's pool before yielding the
     /// next value
-    pub(crate) new_transaction_reciever: Receiver<PendingTransaction<T>>,
+    pub(crate) new_transaction_receiver: Option<Receiver<PendingTransaction<T>>>,
 }
 
 impl<T: TransactionOrdering> BestTransactions<T> {
@@ -87,7 +91,7 @@ impl<T: TransactionOrdering> BestTransactions<T> {
     /// Non-blocking read on the new pending transactions subscription channel
     fn try_recv(&mut self) -> Option<PendingTransaction<T>> {
         loop {
-            match self.new_transaction_reciever.try_recv() {
+            match self.new_transaction_receiver.as_mut()?.try_recv() {
                 Ok(tx) => return Some(tx),
                 // note TryRecvError::Lagged can be returned here, which is an error that attempts
                 // to correct itself on consecutive try_recv() attempts
@@ -126,6 +130,10 @@ impl<T: TransactionOrdering> crate::traits::BestTransactions for BestTransaction
     fn mark_invalid(&mut self, tx: &Self::Item) {
         BestTransactions::mark_invalid(self, tx)
     }
+
+    fn no_updates(&mut self) {
+        self.new_transaction_receiver.take();
+    }
 }
 
 impl<T: TransactionOrdering> Iterator for BestTransactions<T> {

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

@@ -88,7 +88,7 @@ impl<T: TransactionOrdering> PendingPool<T> {
             all: self.by_id.clone(),
             independent: self.independent_transactions.clone(),
             invalid: Default::default(),
-            new_transaction_reciever: self.new_transaction_notifier.subscribe(),
+            new_transaction_receiver: Some(self.new_transaction_notifier.subscribe()),
         }
     }
 

crates/transaction-pool/src/traits.rs

@@ -509,11 +509,20 @@ pub trait BestTransactions: Iterator + Send {
     /// In other words, this must remove the given transaction _and_ drain all transaction that
     /// depend on it.
     fn mark_invalid(&mut self, transaction: &Self::Item);
+
+    /// An iterator may be able to receive additional pending transactions that weren't present it
+    /// the pool when it was created.
+    ///
+    /// This ensures that iterator will return the best transaction that it currently knows and not
+    /// listen to pool updates.
+    fn no_updates(&mut self);
 }
 
 /// A no-op implementation that yields no transactions.
 impl<T> BestTransactions for std::iter::Empty<T> {
     fn mark_invalid(&mut self, _tx: &T) {}
+
+    fn no_updates(&mut self) {}
 }
 
 /// Trait for transaction types used inside the pool