Document lockout_intervals and tiny niceties (#10925)

Author: ryoqun

core/src/consensus.rs

@@ -66,6 +66,8 @@ pub(crate) struct ComputedBankState {
     pub voted_stakes: VotedStakes,
     pub total_stake: Stake,
     pub bank_weight: u128,
+    // Tree of intervals of lockouts of the form [slot, slot + slot.lockout],
+    // keyed by end of the range
     pub lockout_intervals: LockoutIntervals,
     pub pubkey_votes: Vec<(Pubkey, Slot)>,
 }
@@ -456,7 +458,7 @@ impl Tower {
                         .lockout_intervals;
                     // Find any locked out intervals in this bank with endpoint >= last_vote,
                     // implies they are locked out at last_vote
-                    for (_, value) in lockout_intervals.range((Included(last_voted_slot), Unbounded)) {
+                    for (_lockout_ineterval_end, value) in lockout_intervals.range((Included(last_voted_slot), Unbounded)) {
                         for (lockout_interval_start, vote_account_pubkey) in value {
                             // Only count lockouts on slots that are:
                             // 1) Not ancestors of `last_vote`
@@ -1196,11 +1198,15 @@ pub mod test {
         // count toward the switch threshold. This means the other validator's
         // vote lockout no longer counts
         vote_simulator.set_root(43);
+        // Refresh ancestors and descendants for new root.
+        let ancestors = vote_simulator.bank_forks.read().unwrap().ancestors();
+        let descendants = vote_simulator.bank_forks.read().unwrap().descendants();
+
         assert_eq!(
             tower.check_switch_threshold(
                 110,
-                &vote_simulator.bank_forks.read().unwrap().ancestors(),
-                &vote_simulator.bank_forks.read().unwrap().descendants(),
+                &ancestors,
+                &descendants,
                 &vote_simulator.progress,
                 total_stake,
                 bank0.epoch_vote_accounts(0).unwrap(),

core/src/heaviest_subtree_fork_choice.rs

@@ -580,10 +580,10 @@ impl ForkChoice for HeaviestSubtreeForkChoice {
         bank_forks: &RwLock<BankForks>,
     ) -> (Arc<Bank>, Option<Arc<Bank>>) {
         let last_voted_slot = tower.last_voted_slot();
-        let heaviest_slot_on_same_voted_fork = last_voted_slot.map(|last_vote| {
+        let heaviest_slot_on_same_voted_fork = last_voted_slot.map(|last_voted_slot| {
             let heaviest_slot_on_same_voted_fork =
-                self.best_slot(last_vote).expect("last_vote is a frozen bank so must have been added to heaviest_subtree_fork_choice at time of freezing");
-            if heaviest_slot_on_same_voted_fork == last_vote {
+                self.best_slot(last_voted_slot).expect("a bank at last_voted_slot is a frozen bank so must have been added to heaviest_subtree_fork_choice at time of freezing");
+            if heaviest_slot_on_same_voted_fork == last_voted_slot {
                 None
             } else {
                 Some(heaviest_slot_on_same_voted_fork)

core/src/progress_map.rs

@@ -14,7 +14,9 @@ use std::{
     sync::{Arc, RwLock},
 };
 
-pub(crate) type LockoutIntervals = BTreeMap<Slot, Vec<(Slot, Rc<Pubkey>)>>;
+type VotedSlot = Slot;
+type ExpirationSlot = Slot;
+pub(crate) type LockoutIntervals = BTreeMap<ExpirationSlot, Vec<(VotedSlot, Rc<Pubkey>)>>;
 
 #[derive(Default)]
 pub(crate) struct ReplaySlotStats(ConfirmationTiming);