adding comments

pallets/subtensor/src/registration.rs

@@ -434,6 +434,10 @@ impl<T: Config> Pallet<T> {
         let mut earliest_registration_in_immunity: u64 = u64::MAX;
         let mut uid_to_prune: u16 = 0;
         let mut uid_to_prune_in_immunity: u16 = 0;
+
+        // This boolean is used instead of checking if min_score == u16::MAX, to avoid the case
+        // where all non-immune neurons have pruning score u16::MAX
+        // This may be unlikely in practice.
         let mut found_non_immune = false;
 
         let neurons_n = Self::get_subnetwork_n(netuid);
@@ -448,6 +452,9 @@ impl<T: Config> Pallet<T> {
             let is_immune = Self::get_neuron_is_immune(netuid, neuron_uid);
 
             if is_immune {
+                // if the immune neuron has a lower pruning score than the minimum for immune neurons,
+                // or, if the pruning scores are equal and the immune neuron was registered earlier than the current minimum for immune neurons,
+                // then update the minimum pruning score and the uid to prune for immune neurons
                 if pruning_score < min_score_in_immunity
                     || (pruning_score == min_score_in_immunity
                         && block_at_registration < earliest_registration_in_immunity)
@@ -458,6 +465,9 @@ impl<T: Config> Pallet<T> {
                 }
             } else {
                 found_non_immune = true;
+                // if the non-immune neuron has a lower pruning score than the minimum for non-immune neurons,
+                // or, if the pruning scores are equal and the non-immune neuron was registered earlier than the current minimum for non-immune neurons,
+                // then update the minimum pruning score and the uid to prune for non-immune neurons
                 if pruning_score < min_score
                     || (pruning_score == min_score && block_at_registration < earliest_registration)
                 {

pallets/subtensor/src/utils.rs

@@ -460,7 +460,7 @@ impl<T: Config> Pallet<T> {
         ImmunityPeriod::<T>::insert(netuid, immunity_period);
         Self::deposit_event(Event::ImmunityPeriodSet(netuid, immunity_period));
     }
-
+    /// Check if a neuron is in immunity based on the current block
     pub fn get_neuron_is_immune(netuid: u16, uid: u16) -> bool {
         let registered_at = Self::get_neuron_block_at_registration(netuid, uid);
         let current_block = Self::get_current_block_as_u64();

pallets/subtensor/tests/registration.rs

@@ -551,13 +551,12 @@ fn test_burn_registration_pruning_scenarios() {
         let max_allowed_uids = 6;
         let immunity_period = 5000;
 
+        // Initial setup
         SubtensorModule::set_burn(netuid, burn_cost);
         SubtensorModule::set_max_allowed_uids(netuid, max_allowed_uids);
         SubtensorModule::set_target_registrations_per_interval(netuid, max_allowed_uids);
         SubtensorModule::set_immunity_period(netuid, immunity_period);
 
-        // SubtensorModule::set_immunity_period(netuid, immunity_period);
-
         add_network(netuid, tempo, 0);
 
         let mint_balance = burn_cost * u64::from(max_allowed_uids) + 1_000_000_000;
@@ -575,7 +574,7 @@ fn test_burn_registration_pruning_scenarios() {
 
         // Note: pruning score is set to u16::MAX after getting neuron to prune
 
-        // 1. Test all immune neurons
+        // 1. Test if all immune neurons
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 0), true);
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 1), true);
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 2), true);
@@ -591,12 +590,13 @@ fn test_burn_registration_pruning_scenarios() {
         SubtensorModule::set_pruning_score_for_uid(netuid, 1, 50);
         SubtensorModule::set_pruning_score_for_uid(netuid, 2, 50);
 
-        // Should get the oldest neuron
+        // Should get the oldest neuron (i.e., neuron that was registered first)
         assert_eq!(SubtensorModule::get_neuron_to_prune(netuid), 1);
 
-        // 3. Test no immune neurons
+        // 3. Test if no immune neurons
         step_block(immunity_period);
 
+        // ensure all neurons are non-immune
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 0), false);
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 1), false);
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 2), false);
@@ -626,6 +626,7 @@ fn test_burn_registration_pruning_scenarios() {
             step_block(1);
         }
 
+        // Ensure all new neurons are immune
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 3), true);
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 4), true);
         assert_eq!(SubtensorModule::get_neuron_is_immune(netuid, 5), true);