feat(bolt-sidecar): AccountStateCache with metrics

bolt-sidecar/src/state/account_state.rs

@@ -0,0 +1,36 @@
+use std::ops::{Deref, DerefMut};
+
+use alloy::primitives::Address;
+
+use crate::{common::score_cache::ScoreCache, primitives::AccountState, telemetry::ApiMetrics};
+
+const GET_SCORE: isize = 4;
+const INSERT_SCORE: isize = 4;
+const UPDATE_SCORE: isize = -1;
+
+/// A scored cache for account states.
+#[derive(Debug, Default)]
+pub struct AccountStateCache(
+    pub ScoreCache<GET_SCORE, INSERT_SCORE, UPDATE_SCORE, Address, AccountState>,
+);
+
+impl Deref for AccountStateCache {
+    type Target = ScoreCache<GET_SCORE, INSERT_SCORE, UPDATE_SCORE, Address, AccountState>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for AccountStateCache {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl AccountStateCache {
+    /// Insert an account state into the cache, and update the metrics.
+    pub fn insert(&mut self, address: Address, account_state: AccountState) {
+        ApiMetrics::set_account_states(self.len());
+        self.0.insert(address, account_state);
+    }
+}

bolt-sidecar/src/state/execution.rs

@@ -20,7 +20,7 @@ use crate::{
     telemetry::ApiMetrics,
 };
 
-use super::fetcher::StateFetcher;
+use super::{account_state::AccountStateCache, fetcher::StateFetcher};
 
 /// Possible commitment validation errors.
 ///
@@ -126,11 +126,6 @@ impl ValidationError {
     }
 }
 
-const GET_SCORE: isize = 4;
-const INSERT_SCORE: isize = 4;
-const UPDATE_SCORE: isize = -1;
-type AccountStatesCache = ScoreCache<GET_SCORE, INSERT_SCORE, UPDATE_SCORE, Address, AccountState>;
-
 /// The minimal state of the execution layer at some block number (`head`).
 /// This is the state that is needed to simulate commitments.
 /// It contains per-address nonces and balances, as well as the minimum basefee.
@@ -161,7 +156,7 @@ pub struct ExecutionState<C> {
     /// When a commitment request is made from an account its score is bumped of
     /// [ACCOUNT_STATE_SCORE_BUMP], and when it updated it is decreased by
     /// [ACCOUNT_STATE_UPDATE_PENALTY].
-    account_states: AccountStatesCache,
+    account_states: AccountStateCache,
     /// The block templates by target SLOT NUMBER.
     /// We have multiple block templates because in rare cases we might have multiple
     /// proposal duties for a single lookahead.
@@ -226,7 +221,7 @@ impl<C: StateFetcher> ExecutionState<C> {
             limits,
             client,
             slot: 0,
-            account_states: AccountStatesCache::with_max_len(num_accounts),
+            account_states: AccountStateCache(ScoreCache::with_max_len(num_accounts)),
             block_templates: HashMap::new(),
             // Load the default KZG settings
             kzg_settings: EnvKzgSettings::default(),

bolt-sidecar/src/state/mod.rs

@@ -23,6 +23,10 @@ pub use consensus::ConsensusState;
 pub mod head_tracker;
 pub use head_tracker::HeadTracker;
 
+/// Module that defines the account state cache.
+pub mod account_state;
+pub use account_state::AccountStateCache;
+
 /// The deadline for a which a commitment is considered valid.
 #[derive(Debug)]
 pub struct CommitmentDeadline {

bolt-sidecar/src/telemetry/metrics.rs

@@ -28,6 +28,8 @@ const GROSS_TIP_REVENUE: &str = "bolt_sidecar_gross_tip_revenue";
 //  Gauges ------------------------------------------------------------------
 /// Gauge for the latest slot number
 const LATEST_HEAD: &str = "bolt_sidecar_latest_head";
+/// Number of account states saved in cache.
+const ACCOUNT_STATES: &str = "bolt_sidecar_account_states";
 
 //  Histograms --------------------------------------------------------------
 /// Histogram for the total duration of HTTP requests in seconds.
@@ -52,6 +54,7 @@ impl ApiMetrics {
 
         // Gauges
         describe_gauge!(LATEST_HEAD, "Latest slot number");
+        describe_gauge!(ACCOUNT_STATES, "Number of account states saved in cache");
 
         // Histograms
         describe_histogram!(
@@ -119,6 +122,10 @@ impl ApiMetrics {
         gauge!(LATEST_HEAD).set(slot);
     }
 
+    pub fn set_account_states(count: usize) {
+        gauge!(ACCOUNT_STATES).set(count as f64);
+    }
+
     /// Mixed ----------------------------------------------------------------
 
     /// Observes the duration of an HTTP request by storing it in a histogram,