Fix some low-hanging FIXMEs

beacon_node/beacon_chain/src/beacon_fork_choice_store.rs

@@ -197,7 +197,6 @@ where
         };
         let finalized_checkpoint = justified_checkpoint;
 
-        // FIXME(sproul): avoid `to_vec` perf penalty
         Self {
             store,
             balances_cache: <_>::default(),

beacon_node/beacon_chain/src/canonical_head.rs

@@ -626,7 +626,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     .get_full_block(&new_view.head_block_root, None)?
                     .ok_or(Error::MissingBeaconBlock(new_view.head_block_root))?;
 
-                // FIXME(sproul): use advanced state?
                 let beacon_state_root = beacon_block.state_root();
                 let beacon_state: BeaconState<T::EthSpec> = self
                     .get_state(&beacon_state_root, Some(beacon_block.slot()))?
@@ -1288,8 +1287,7 @@ fn observe_head_block_delays<E: EthSpec, S: SlotClock>(
         // If the block was enshrined as head too late for attestations to be created for it,
         // log a debug warning and increment a metric.
         if late_head {
-            // FIXME(sproul): restore this metric, idk where it went
-            // metrics::inc_counter(&metrics::BEACON_BLOCK_HEAD_SLOT_START_DELAY_EXCEEDED_TOTAL);
+            metrics::inc_counter(&metrics::BEACON_BLOCK_HEAD_SLOT_START_DELAY_EXCEEDED_TOTAL);
             debug!(
                 log,
                 "Delayed head block";

beacon_node/beacon_chain/src/lib.rs

@@ -72,7 +72,6 @@ pub use store;
 pub use timeout_rw_lock::TimeoutRwLock;
 pub use types;
 
-// FIXME(sproul): compatibility shim
 pub mod validator_pubkey_cache {
     use crate::BeaconChainTypes;
 

beacon_node/beacon_chain/src/metrics.rs

@@ -813,6 +813,11 @@ lazy_static! {
         // [0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50]
         decimal_buckets(-1,2)
     );
+    pub static ref BEACON_BLOCK_HEAD_SLOT_START_DELAY_EXCEEDED_TOTAL: Result<IntCounter> = try_create_int_counter(
+        "beacon_block_head_slot_start_delay_exceeded_total",
+        "Triggered when the duration between the start of the block's slot and the current time \
+        will result in failed attestations.",
+    );
     pub static ref BEACON_BLOCK_HEAD_MISSED_ATT_DEADLINE_LATE: Result<IntCounter> = try_create_int_counter(
         "beacon_block_head_missed_att_deadline_late",
         "Total number of delayed head blocks that arrived late"