feat: implement chunk validator assignment

chain/chain/src/test_utils/kv_runtime.rs

@@ -523,6 +523,7 @@ impl EpochManagerAdapter for MockEpochManager {
             1,
             1,
             RngSeed::default(),
+            Default::default(),
         )))
     }
 

chain/epoch-manager/src/proposals.rs

@@ -85,6 +85,7 @@ mod old_validator_selection {
     use near_primitives::types::{
         AccountId, Balance, NumSeats, ValidatorId, ValidatorKickoutReason,
     };
+    use near_primitives::validator_mandates::ValidatorMandates;
     use near_primitives::version::ProtocolVersion;
     use rand::{RngCore, SeedableRng};
     use rand_hc::Hc128Rng;
@@ -248,6 +249,9 @@ mod old_validator_selection {
             .map(|(index, s)| (s.account_id().clone(), index as ValidatorId))
             .collect::<HashMap<_, _>>();
 
+        // Old validator selection is not aware of chunk validator mandates.
+        let validator_mandates: ValidatorMandates = Default::default();
+
         Ok(EpochInfo::new(
             prev_epoch_info.epoch_height() + 1,
             final_proposals,
@@ -264,6 +268,7 @@ mod old_validator_selection {
             threshold,
             next_version,
             rng_seed,
+            validator_mandates,
         ))
     }
 

chain/epoch-manager/src/test_utils.rs

@@ -20,6 +20,7 @@ use near_primitives::types::{
     ValidatorId, ValidatorKickoutReason,
 };
 use near_primitives::utils::get_num_seats_per_shard;
+use near_primitives::validator_mandates::{ValidatorMandates, ValidatorMandatesConfig};
 use near_primitives::version::PROTOCOL_VERSION;
 use near_store::test_utils::create_test_store;
 
@@ -104,9 +105,17 @@ pub fn epoch_info_with_num_seats(
             })
             .collect()
     };
+    let all_validators = account_to_validators(accounts);
+    // TODO determine required stake per mandate instead of reusing seat price.
+    // TODO determine `min_mandates_per_shard`
+    let num_shards = chunk_producers_settlement.len();
+    let min_mandates_per_shard = 0;
+    let validator_mandates_config =
+        ValidatorMandatesConfig::new(seat_price, min_mandates_per_shard, num_shards);
+    let validator_mandates = ValidatorMandates::new(validator_mandates_config, &all_validators);
     EpochInfo::new(
         epoch_height,
-        account_to_validators(accounts),
+        all_validators,
         validator_to_index,
         block_producers_settlement,
         chunk_producers_settlement,
@@ -120,6 +129,7 @@ pub fn epoch_info_with_num_seats(
         seat_price,
         PROTOCOL_VERSION,
         TEST_SEED,
+        validator_mandates,
     )
 }
 

chain/epoch-manager/src/validator_selection.rs

@@ -7,6 +7,7 @@ use near_primitives::types::validator_stake::ValidatorStake;
 use near_primitives::types::{
     AccountId, Balance, ProtocolVersion, ValidatorId, ValidatorKickoutReason,
 };
+use near_primitives::validator_mandates::{ValidatorMandates, ValidatorMandatesConfig};
 use num_rational::Ratio;
 use std::cmp::{self, Ordering};
 use std::collections::hash_map;
@@ -96,6 +97,7 @@ pub fn proposals_to_epoch_info(
     }
 
     let num_chunk_producers = chunk_producers.len();
+    // Constructing `all_validators` such that a validators position corresponds to its `ValidatorId`.
     let mut all_validators: Vec<ValidatorStake> = Vec::with_capacity(num_chunk_producers);
     let mut validator_to_index = HashMap::new();
     let mut block_producers_settlement = Vec::with_capacity(block_producers.len());
@@ -170,6 +172,16 @@ pub fn proposals_to_epoch_info(
             .collect()
     };
 
+    // We can use `all_validators` to construct mandates Since a validator's position in
+    // `all_validators` corresponds to its `ValidatorId`
+    // TODO determine required stake per mandate instead of reusing seat price.
+    // TODO determine `min_mandates_per_shard`
+    // TODO pre chunk-validation, just pass empty vec instead of `all_validators` to avoid costs?
+    let min_mandates_per_shard = 0;
+    let validator_mandates_config =
+        ValidatorMandatesConfig::new(threshold, min_mandates_per_shard, num_shards as usize);
+    let validator_mandates = ValidatorMandates::new(validator_mandates_config, &all_validators);
+
     let fishermen_to_index = fishermen
         .iter()
         .enumerate()
@@ -192,6 +204,7 @@ pub fn proposals_to_epoch_info(
         threshold,
         next_version,
         rng_seed,
+        validator_mandates,
     ))
 }
 
@@ -619,6 +632,52 @@ mod tests {
         }
     }
 
+    /// This test only verifies that chunk validator mandates are correctly wired up with
+    /// `EpochInfo`. The internals of mandate assignment are tested in the module containing
+    /// [`ValidatorMandates`].
+    #[test]
+    fn test_chunk_validators_sampling() {
+        // When there is 1 CP per shard, they are chosen 100% of the time.
+        let num_shards = 4;
+        let epoch_config = create_epoch_config(
+            num_shards,
+            2 * num_shards,
+            0,
+            ValidatorSelectionConfig {
+                num_chunk_only_producer_seats: 0,
+                minimum_validators_per_shard: 1,
+                minimum_stake_ratio: Ratio::new(160, 1_000_000),
+            },
+        );
+        let prev_epoch_height = 7;
+        let prev_epoch_info = create_prev_epoch_info(prev_epoch_height, &["test1", "test2"], &[]);
+        let proposals =
+            create_proposals(&[("test1", 15), ("test2", 9), ("test3", 5), ("test4", 3)]);
+
+        let epoch_info = proposals_to_epoch_info(
+            &epoch_config,
+            [0; 32],
+            &prev_epoch_info,
+            proposals,
+            Default::default(),
+            Default::default(),
+            0,
+            PROTOCOL_VERSION,
+            PROTOCOL_VERSION,
+        )
+        .unwrap();
+
+        // Given `epoch_info` and `proposals` above, the sample at a given height is deterministic.
+        let height = 42;
+        let expected_assignments: Vec<HashMap<ValidatorId, u16>> = vec![
+            HashMap::from([(0, 1), (1, 5), (2, 1), (3, 1)]),
+            HashMap::from([(0, 6), (1, 1), (2, 1)]),
+            HashMap::from([(0, 5), (1, 2), (2, 1)]),
+            HashMap::from([(0, 3), (1, 1), (2, 2), (3, 2)]),
+        ];
+        assert_eq!(epoch_info.sample_chunk_validators(height), expected_assignments);
+    }
+
     #[test]
     fn test_validator_assignment_ratio_condition() {
         // There are more seats than proposals, however the

core/primitives/Cargo.toml

@@ -24,6 +24,7 @@ num-rational.workspace = true
 once_cell.workspace = true
 primitive-types.workspace = true
 rand.workspace = true
+rand_chacha.workspace = true
 reed-solomon-erasure.workspace = true
 serde.workspace = true
 serde_json.workspace = true