spec: registry updates v0.6.1

eth2/state_processing/src/per_epoch_processing/registry_updates.rs

@@ -0,0 +1,70 @@
+use super::super::common::initiate_validator_exit;
+use super::Error;
+use itertools::{Either, Itertools};
+use types::*;
+
+/// Peforms a validator registry update, if required.
+///
+/// Spec v0.6.1
+pub fn process_registry_updates(
+    state: &mut BeaconState,
+    current_total_balance: u64,
+    spec: &ChainSpec,
+) -> Result<(), Error> {
+    // Process activation eligibility and ejections.
+    // Collect eligible and exiting validators (we need to avoid mutating the state while iterating).
+    // We assume it's safe to re-order the change in eligibility and `initiate_validator_exit`.
+    // Rest assured exiting validators will still be exited in the same order as in the spec.
+    let current_epoch = state.current_epoch(spec);
+    let is_eligible = |validator: &Validator| {
+        validator.activation_eligibility_epoch == spec.far_future_epoch
+            && validator.effective_balance >= spec.max_effective_balance
+    };
+    let is_exiting_validator = |validator: &Validator| {
+        validator.is_active_at(current_epoch)
+            && validator.effective_balance <= spec.ejection_balance
+    };
+    let (eligible_validators, exiting_validators): (Vec<_>, Vec<_>) = state
+        .validator_registry
+        .iter()
+        .enumerate()
+        .filter(|(_, validator)| is_eligible(validator) || is_exiting_validator(validator))
+        .partition_map(|(index, validator)| {
+            if is_eligible(validator) {
+                Either::Left(index)
+            } else {
+                Either::Right(index)
+            }
+        });
+    for index in eligible_validators {
+        state.validator_registry[index].activation_eligibility_epoch = current_epoch;
+    }
+    for index in exiting_validators {
+        initiate_validator_exit(state, index, spec)?;
+    }
+
+    // Queue validators eligible for activation and not dequeued for activation prior to finalized epoch
+    let activation_queue = state
+        .validator_registry
+        .iter()
+        .enumerate()
+        .filter(|(_, validator)| {
+            validator.activation_eligibility_epoch != spec.far_future_epoch
+                && validator.activation_epoch
+                    >= state.get_delayed_activation_exit_epoch(state.finalized_epoch, spec)
+        })
+        .sorted_by_key(|(_, validator)| validator.activation_eligibility_epoch)
+        .map(|(index, _)| index)
+        .collect_vec();
+
+    let churn_limit = state.get_churn_limit(spec)? as usize;
+    let delayed_activation_epoch = state.get_delayed_activation_exit_epoch(current_epoch, spec);
+    for index in activation_queue.into_iter().take(churn_limit) {
+        let validator = &mut state.validator_registry[index];
+        if validator.activation_epoch == spec.far_future_epoch {
+            validator.activation_epoch = delayed_activation_epoch;
+        }
+    }
+
+    Ok(())
+}