avoid double iteration by using lifetimes

Author: jxs

beacon_node/lighthouse_network/src/service/mod.rs

@@ -711,7 +711,7 @@ impl<E: EthSpec> Network<E> {
         for kind in fork_core_topics::<E>(
             &new_fork,
             &self.fork_context.spec,
-            &self.network_globals.topic_config(),
+            &self.network_globals.as_topic_config(),
         ) {
             let topic = GossipTopic::new(kind, GossipEncoding::default(), new_fork_digest);
             self.subscribe(topic);

beacon_node/lighthouse_network/src/types/globals.rs

@@ -185,10 +185,10 @@ impl<E: EthSpec> NetworkGlobals<E> {
     }
 
     /// Returns the TopicConfig to compute the set of Gossip topics for a given fork
-    pub fn topic_config(&self) -> TopicConfig {
+    pub fn as_topic_config(&self) -> TopicConfig {
         TopicConfig {
             subscribe_all_data_column_subnets: self.config.subscribe_all_data_column_subnets,
-            sampling_subnets: self.sampling_subnets.iter().copied().collect(),
+            sampling_subnets: &self.sampling_subnets,
         }
     }
 

beacon_node/lighthouse_network/src/types/topics.rs

@@ -1,5 +1,6 @@
 use gossipsub::{IdentTopic as Topic, TopicHash};
 use serde::{Deserialize, Serialize};
+use std::collections::HashSet;
 use strum::AsRefStr;
 use types::{ChainSpec, DataColumnSubnetId, EthSpec, ForkName, SubnetId, SyncSubnetId, Unsigned};
 
@@ -41,9 +42,10 @@ pub const LIGHT_CLIENT_GOSSIP_TOPICS: [GossipKind; 2] = [
     GossipKind::LightClientOptimisticUpdate,
 ];
 
-pub struct TopicConfig {
+#[derive(Debug)]
+pub struct TopicConfig<'a> {
     pub subscribe_all_data_column_subnets: bool,
-    pub sampling_subnets: Vec<DataColumnSubnetId>,
+    pub sampling_subnets: &'a HashSet<DataColumnSubnetId>,
 }
 
 /// Returns the core topics associated with each fork that are new to the previous fork
@@ -82,7 +84,7 @@ pub fn fork_core_topics<E: EthSpec>(
                     )));
                 }
             } else {
-                for column_subnet in &topic_config.sampling_subnets {
+                for column_subnet in topic_config.sampling_subnets {
                     topics.push(GossipKind::DataColumnSidecar(*column_subnet));
                 }
             }
@@ -499,9 +501,10 @@ mod tests {
         type E = MainnetEthSpec;
         let spec = E::default_spec();
         let mut all_topics = Vec::new();
+        let sampling_subnets = HashSet::new();
         let topic_config = TopicConfig {
             subscribe_all_data_column_subnets: false,
-            sampling_subnets: vec![],
+            sampling_subnets: &sampling_subnets,
         };
         let mut electra_core_topics =
             fork_core_topics::<E>(&ForkName::Electra, &spec, &topic_config);

beacon_node/network/src/service.rs

@@ -714,7 +714,7 @@ impl<T: BeaconChainTypes> NetworkService<T> {
                 for topic_kind in core_topics_to_subscribe::<T::EthSpec>(
                     self.fork_context.current_fork(),
                     &self.fork_context.spec,
-                    &self.network_globals.topic_config(),
+                    &self.network_globals.as_topic_config(),
                 ) {
                     for fork_digest in self.required_gossip_fork_digests() {
                         let topic = GossipTopic::new(
@@ -910,7 +910,7 @@ impl<T: BeaconChainTypes> NetworkService<T> {
         let core_topics = core_topics_to_subscribe::<T::EthSpec>(
             self.fork_context.current_fork(),
             &self.fork_context.spec,
-            &self.network_globals.topic_config(),
+            &self.network_globals.as_topic_config(),
         );
         let core_topics: HashSet<&GossipKind> = HashSet::from_iter(&core_topics);
         let subscriptions = self.network_globals.gossipsub_subscriptions.read();