Remove pubkey_bytes from ValidatorPubkeyCache

Squashed commit of the following:

commit a0b3490
Author: Michael Sproul <michael@sigmaprime.io>
Date:   Mon Oct 28 12:03:58 2024 +1100

    Remove pubkey_bytes from ValidatorPubkeyCache

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -1558,9 +1558,13 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         &self,
         validator_index: usize,
     ) -> Result<Option<PublicKeyBytes>, Error> {
-        let pubkey_cache = self.validator_pubkey_cache.read();
-
-        Ok(pubkey_cache.get_pubkey_bytes(validator_index).copied())
+        let head = self.canonical_head.cached_head();
+        Ok(head
+            .snapshot
+            .beacon_state
+            .get_validator(validator_index)
+            .ok()
+            .map(|v| v.pubkey))
     }
 
     /// As per `Self::validator_pubkey_bytes` but will resolve multiple indices at once to avoid
@@ -1572,12 +1576,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         &self,
         validator_indices: &[usize],
     ) -> Result<HashMap<usize, PublicKeyBytes>, Error> {
-        let pubkey_cache = self.validator_pubkey_cache.read();
+        let head = self.canonical_head.cached_head();
 
         let mut map = HashMap::with_capacity(validator_indices.len());
         for &validator_index in validator_indices {
-            if let Some(pubkey) = pubkey_cache.get_pubkey_bytes(validator_index) {
-                map.insert(validator_index, *pubkey);
+            if let Ok(validator) = head.snapshot.beacon_state.get_validator(validator_index) {
+                map.insert(validator_index, validator.pubkey);
             }
         }
         Ok(map)

beacon_node/beacon_chain/src/validator_pubkey_cache.rs

@@ -20,7 +20,6 @@ use types::{BeaconState, FixedBytesExtended, Hash256, PublicKey, PublicKeyBytes}
 pub struct ValidatorPubkeyCache<T: BeaconChainTypes> {
     pubkeys: Vec<PublicKey>,
     indices: HashMap<PublicKeyBytes, usize>,
-    pubkey_bytes: Vec<PublicKeyBytes>,
     _phantom: PhantomData<T>,
 }
 
@@ -35,7 +34,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
         let mut cache = Self {
             pubkeys: vec![],
             indices: HashMap::new(),
-            pubkey_bytes: vec![],
             _phantom: PhantomData,
         };
 
@@ -49,7 +47,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
     pub fn load_from_store(store: BeaconStore<T>) -> Result<Self, BeaconChainError> {
         let mut pubkeys = vec![];
         let mut indices = HashMap::new();
-        let mut pubkey_bytes = vec![];
 
         for validator_index in 0.. {
             if let Some(db_pubkey) =
@@ -58,7 +55,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
                 let (pk, pk_bytes) = DatabasePubkey::as_pubkey(&db_pubkey)?;
                 pubkeys.push(pk);
                 indices.insert(pk_bytes, validator_index);
-                pubkey_bytes.push(pk_bytes);
             } else {
                 break;
             }
@@ -67,7 +63,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
         Ok(ValidatorPubkeyCache {
             pubkeys,
             indices,
-            pubkey_bytes,
             _phantom: PhantomData,
         })
     }
@@ -101,7 +96,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
     where
         I: Iterator<Item = PublicKeyBytes> + ExactSizeIterator,
     {
-        self.pubkey_bytes.reserve(validator_keys.len());
         self.pubkeys.reserve(validator_keys.len());
         self.indices.reserve(validator_keys.len());
 
@@ -127,7 +121,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
             ));
 
             self.pubkeys.push(pubkey);
-            self.pubkey_bytes.push(pubkey_bytes);
             self.indices.insert(pubkey_bytes, i);
         }
 
@@ -144,11 +137,6 @@ impl<T: BeaconChainTypes> ValidatorPubkeyCache<T> {
         self.get_index(pubkey).and_then(|index| self.get(index))
     }
 
-    /// Get the public key (in bytes form) for a validator with index `i`.
-    pub fn get_pubkey_bytes(&self, i: usize) -> Option<&PublicKeyBytes> {
-        self.pubkey_bytes.get(i)
-    }
-
     /// Get the index of a validator with `pubkey`.
     pub fn get_index(&self, pubkey: &PublicKeyBytes) -> Option<usize> {
         self.indices.get(pubkey).copied()