Track the most recently active validators and sample the superblock committee from them

data_structures/src/chain/mod.rs

@@ -4592,7 +4592,7 @@ mod tests {
 
     use crate::{
         proto::versioning::{ProtocolVersion, VersionedHashable},
-        superblock::{mining_build_superblock, ARSIdentities},
+        superblock::{mining_build_superblock, ValidatorIdentities},
         transaction::{CommitTransactionBody, RevealTransactionBody, VTTransactionBody},
     };
 
@@ -6473,11 +6473,11 @@ mod tests {
 
         let expected_order = vec![p1_bls, p2_bls, p3_bls];
         let ordered_identities = rep_engine.get_rep_ordered_ars_list();
-        let ars_identities = ARSIdentities::new(ordered_identities);
+        let validator_identities = ValidatorIdentities::new(ordered_identities);
 
         assert_eq!(
             expected_order,
-            ars_identities.get_rep_ordered_bn256_list(&alt_keys)
+            validator_identities.get_ordered_bn256_list(&alt_keys)
         );
     }
 
@@ -6515,11 +6515,11 @@ mod tests {
 
         let expected_order = vec![p1_bls, p2_bls, p3_bls];
         let ordered_identities = rep_engine.get_rep_ordered_ars_list();
-        let ars_identities = ARSIdentities::new(ordered_identities);
+        let validator_identities = ValidatorIdentities::new(ordered_identities);
 
         assert_eq!(
             expected_order,
-            ars_identities.get_rep_ordered_bn256_list(&alt_keys)
+            validator_identities.get_ordered_bn256_list(&alt_keys)
         );
     }
 
@@ -6573,11 +6573,11 @@ mod tests {
 
         let expected_order = vec![p1_bls, p2_bls, p4_bls, p5_bls, p3_bls];
         let ordered_identities = rep_engine.get_rep_ordered_ars_list();
-        let ars_identities = ARSIdentities::new(ordered_identities);
+        let validator_identities = ValidatorIdentities::new(ordered_identities);
 
         assert_eq!(
             expected_order,
-            ars_identities.get_rep_ordered_bn256_list(&alt_keys)
+            validator_identities.get_ordered_bn256_list(&alt_keys)
         );
     }
 

data_structures/src/staking/stakes.rs

@@ -1,5 +1,6 @@
 use std::{
-    collections::{btree_map::Entry, BTreeMap},
+    cmp::PartialOrd,
+    collections::{btree_map::Entry, BTreeMap, HashSet},
     fmt::{Debug, Display},
     ops::{Add, Div, Mul, Sub},
 };
@@ -80,6 +81,9 @@ where
     ///  it never gets persisted and rather always read from constants, or hide the field and the related method
     ///  behind a #[test] thing.
     minimum_stakeable: Option<Coins>,
+    /// A listing of all active validators (mined a block or solved a data request) indexed by the validator address
+    /// and the epoch of when it was active as value
+    by_active: BTreeMap<Address, Epoch>,
 }
 
 impl<Address, Coins, Epoch, Power> Stakes<Address, Coins, Epoch, Power>
@@ -108,7 +112,8 @@ where
         + Debug
         + Display
         + Send
-        + Sync,
+        + Sync
+        + PartialOrd,
     Power: Copy + Default + Ord + Add<Output = Power> + Div<Output = Power>,
     u64: From<Coins> + From<Power>,
 {
@@ -251,6 +256,7 @@ where
             // No need to keep the entry if the stake has gone to zero
             if final_coins.is_zero() {
                 by_address_entry.remove();
+                self.by_active.remove(&key.validator);
                 self.by_coins.remove(&CoinsAndAddresses {
                     coins: initial_coins,
                     addresses: key,
@@ -311,6 +317,41 @@ where
         }
     }
 
+    /// Return the total number of validators.
+    pub fn validator_count(&self, active_since: Option<Epoch>) -> usize {
+        match active_since {
+            None => self.by_active.len(),
+            Some(epoch) => {
+                let mut count = 0;
+                for (_, active) in self.by_active.iter() {
+                    if *active >= epoch {
+                        count += 1;
+                    }
+                }
+                count
+            }
+        }
+    }
+
+    /// Get a vector of all validator that were active since a given epoch
+    pub fn get_active_validators(&self, active_since: Epoch) -> Vec<Address> {
+        self.by_active
+            .iter()
+            .filter(|(_, epoch)| **epoch >= active_since)
+            .map(|(address, _)| address.clone())
+            .collect()
+    }
+
+    /// Update the active epoch of the validators passed as an argument
+    pub fn update_active_epoch(&mut self, validators: HashSet<Address>, active: Epoch) {
+        for validator in validators {
+            self.by_active
+                .entry(validator)
+                .and_modify(|validator| *validator = active)
+                .or_insert(active);
+        }
+    }
+
     /// Query stakes by stake key.
     #[inline(always)]
     fn query_by_key(&self, key: StakeKey<Address>) -> StakingResult<Coins, Address, Coins, Epoch> {
@@ -372,7 +413,8 @@ where
         + Debug
         + Display
         + Send
-        + Sync,
+        + Sync
+        + PartialOrd,
     Power: Add<Output = Power> + Copy + Default + Div<Output = Power> + Ord + Debug,
     Wit: Mul<Epoch, Output = Power>,
     u64: From<Wit> + From<Power>,
@@ -419,7 +461,8 @@ where
         + Debug
         + Send
         + Sync
-        + Display,
+        + Display
+        + PartialOrd,
     Power: Add<Output = Power> + Copy + Default + Div<Output = Power> + Ord + Debug,
     Wit: Mul<Epoch, Output = Power>,
     u64: From<Wit> + From<Power>,