Squashed commit of #2439

commit 8847bd0
Author: Paul Hauner <[email protected]>
Date:   Thu Jul 8 18:24:00 2021 +1000

    Add metrics for sync committee fullness

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -2185,6 +2185,13 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             block.body().attestations().len() as f64,
         );
 
+        if let Ok(block) = block.as_altair() {
+            metrics::set_gauge(
+                &metrics::BLOCK_SYNC_AGGREGATE_SET_BITS,
+                block.body.sync_aggregate.num_set_bits() as i64,
+            );
+        }
+
         let db_write_timer = metrics::start_timer(&metrics::BLOCK_PROCESSING_DB_WRITE);
 
         // Store the block and its state, and execute the confirmation batch for the intermediate

beacon_node/beacon_chain/src/metrics.rs

@@ -56,6 +56,10 @@ lazy_static! {
         "beacon_block_processing_attestation_observation_seconds",
         "Time spent hashing and remembering all the attestations in the block"
     );
+    pub static ref BLOCK_SYNC_AGGREGATE_SET_BITS: Result<IntGauge> = try_create_int_gauge(
+        "block_sync_aggregate_set_bits",
+        "The number of true bits in the last sync aggregate in a block"
+    );
 
     /*
      * Block Production

consensus/types/src/sync_aggregate.rs

@@ -75,4 +75,9 @@ impl<T: EthSpec> SyncAggregate<T> {
             sync_committee_signature: AggregateSignature::empty(),
         }
     }
+
+    /// Returns how many bits are `true` in `self.sync_committee_bits`.
+    pub fn num_set_bits(&self) -> usize {
+        self.sync_committee_bits.num_set_bits()
+    }
 }