Set max amount of epochs for state cache to retain states, in order t…

…o avoid high memory usage during long non-finalization periods.

fork_choice_store/src/store.rs

@@ -65,7 +65,7 @@ use crate::{
     },
     segment::{Position, Segment},
     state_cache_processor::StateCacheProcessor,
-    store_config::StoreConfig,
+    store_config::{StoreConfig, MAX_EPOCHS_TO_RETAIN_STATES_IN_CACHE},
     supersets::MultiPhaseAggregateAndProofSets as AggregateAndProofSupersets,
     validations::validate_merge_block,
 };
@@ -1900,6 +1900,7 @@ impl<P: Preset> Store<P> {
         self.update_head_segment_id();
 
         self.blob_cache.on_slot(new_tick.slot);
+        self.prune_state_cache()?;
 
         let changes = if self.reorganized(old_head_segment_id) {
             ApplyTickChanges::Reorganized {
@@ -2461,11 +2462,20 @@ impl<P: Preset> Store<P> {
         self.accepted_blob_sidecars
             .retain(|(slot, _, _), _| finalized_slot <= *slot);
         self.prune_checkpoint_states();
-        self.state_cache.prune(finalized_slot).ok();
+        self.prune_state_cache().ok();
         self.aggregate_and_proof_supersets
             .prune(self.finalized_epoch());
     }
 
+    fn prune_state_cache(&self) -> Result<()> {
+        let prune_slot = self
+            .slot()
+            .saturating_sub(P::SlotsPerEpoch::U64 * MAX_EPOCHS_TO_RETAIN_STATES_IN_CACHE)
+            .max(self.finalized_slot());
+
+        self.state_cache.prune(prune_slot)
+    }
+
     /// Applies changes to [`Store.latest_messages`] and computes changes to attesting balances.
     ///
     /// Roughly corresponds to [`update_latest_messages`] from the Fork Choice specification.

fork_choice_store/src/store_config.rs

@@ -4,6 +4,7 @@ use derivative::Derivative;
 use types::config::Config as ChainConfig;
 
 pub const DEFAULT_CACHE_LOCK_TIMEOUT_MILLIS: u64 = 1500;
+pub const MAX_EPOCHS_TO_RETAIN_STATES_IN_CACHE: u64 = 8;
 
 #[derive(Clone, Copy, Derivative)]
 #[derivative(Default)]