v2.1: Add not unique leader discovery (backport of #3546) (#3658)

Add not unique leader discovery (#3546)

* rename get_leader_sockets to get_unique_leader_sockets

* Add methods for getting not unique tpu sockets

(cherry picked from commit dffcdb4)

Co-authored-by: kirill lykov <kirill.lykov@anza.xyz>

tpu-client/src/nonblocking/tpu_client.rs

@@ -19,7 +19,7 @@ use {
         response::{RpcContactInfo, SlotUpdate},
     },
     solana_sdk::{
-        clock::{Slot, DEFAULT_MS_PER_SLOT},
+        clock::{Slot, DEFAULT_MS_PER_SLOT, NUM_CONSECUTIVE_LEADER_SLOTS},
         commitment_config::CommitmentConfig,
         epoch_info::EpochInfo,
         pubkey::Pubkey,
@@ -122,24 +122,43 @@ impl LeaderTpuCache {
         )
     }
 
-    // Get the TPU sockets for the current leader and upcoming leaders according to fanout size
+    // Get the TPU sockets for the current leader and upcoming *unique* leaders according to fanout size.
+    fn get_unique_leader_sockets(
+        &self,
+        estimated_current_slot: Slot,
+        fanout_slots: u64,
+    ) -> Vec<SocketAddr> {
+        let all_leader_sockets = self.get_leader_sockets(estimated_current_slot, fanout_slots);
+
+        let mut unique_sockets = Vec::new();
+        let mut seen = HashSet::new();
+
+        for socket in all_leader_sockets {
+            if seen.insert(socket) {
+                unique_sockets.push(socket);
+            }
+        }
+
+        unique_sockets
+    }
+
+    // Get the TPU sockets for the current leader and upcoming leaders according to fanout size.
     fn get_leader_sockets(
         &self,
         estimated_current_slot: Slot,
         fanout_slots: u64,
     ) -> Vec<SocketAddr> {
-        let mut leader_set = HashSet::new();
         let mut leader_sockets = Vec::new();
         // `first_slot` might have been advanced since caller last read the `estimated_current_slot`
         // value. Take the greater of the two values to ensure we are reading from the latest
         // leader schedule.
         let current_slot = std::cmp::max(estimated_current_slot, self.first_slot);
-        for leader_slot in current_slot..current_slot + fanout_slots {
+        for leader_slot in (current_slot..current_slot + fanout_slots)
+            .step_by(NUM_CONSECUTIVE_LEADER_SLOTS as usize)
+        {
             if let Some(leader) = self.get_slot_leader(leader_slot) {
                 if let Some(tpu_socket) = self.leader_tpu_map.get(leader) {
-                    if leader_set.insert(*leader) {
-                        leader_sockets.push(*tpu_socket);
-                    }
+                    leader_sockets.push(*tpu_socket);
                 } else {
                     // The leader is probably delinquent
                     trace!("TPU not available for leader {}", leader);
@@ -411,7 +430,7 @@ where
     ) -> TransportResult<()> {
         let leaders = self
             .leader_tpu_service
-            .leader_tpu_sockets(self.fanout_slots);
+            .unique_leader_tpu_sockets(self.fanout_slots);
         let futures = leaders
             .iter()
             .map(|addr| {
@@ -455,7 +474,7 @@ where
     ) -> TransportResult<()> {
         let leaders = self
             .leader_tpu_service
-            .leader_tpu_sockets(self.fanout_slots);
+            .unique_leader_tpu_sockets(self.fanout_slots);
         let futures = leaders
             .iter()
             .map(|addr| {
@@ -568,7 +587,7 @@ where
                         let wire_transaction = serialize(transaction).unwrap();
                         let leaders = self
                             .leader_tpu_service
-                            .leader_tpu_sockets(self.fanout_slots);
+                            .unique_leader_tpu_sockets(self.fanout_slots);
                         futures.extend(send_wire_transaction_futures(
                             &progress_bar,
                             &progress,
@@ -803,6 +822,14 @@ impl LeaderTpuService {
         self.recent_slots.estimated_current_slot()
     }
 
+    pub fn unique_leader_tpu_sockets(&self, fanout_slots: u64) -> Vec<SocketAddr> {
+        let current_slot = self.recent_slots.estimated_current_slot();
+        self.leader_tpu_cache
+            .read()
+            .unwrap()
+            .get_unique_leader_sockets(current_slot, fanout_slots)
+    }
+
     pub fn leader_tpu_sockets(&self, fanout_slots: u64) -> Vec<SocketAddr> {
         let current_slot = self.recent_slots.estimated_current_slot();
         self.leader_tpu_cache

tpu-client/src/tpu_client.rs

@@ -119,7 +119,7 @@ where
         let leaders = self
             .tpu_client
             .get_leader_tpu_service()
-            .leader_tpu_sockets(self.tpu_client.get_fanout_slots());
+            .unique_leader_tpu_sockets(self.tpu_client.get_fanout_slots());
 
         for tpu_address in &leaders {
             let cache = self.tpu_client.get_connection_cache();