change store::on_gossip_attestation to take a ref to signed attestations (#278)

Closes #271 

This pr changes `on_gossip_attestation` in both `store.rs` and `lib.rs`
to accept `&SignedAttestation` instead of taking ownership to avoid an
unnecessary clone at the call site when self-delivering attestations to
`gossip_signatures`, since only the inner data field (a small
`AttestationData`) needs to be cloned to construct the Attestation.

Co-authored-by: Tomás Grüner <47506558+MegaRedHand@users.noreply.github.com>

Author: d4m014

crates/blockchain/src/lib.rs

@@ -197,7 +197,7 @@ impl BlockChainServer {
             // this the aggregator never sees its own validator's signature in
             // gossip_signatures and it is excluded from aggregated proofs.
             if self.is_aggregator {
-                let _ = store::on_gossip_attestation(&mut self.store, signed_attestation.clone())
+                let _ = store::on_gossip_attestation(&mut self.store, &signed_attestation)
                     .inspect_err(|err| {
                         warn!(%slot, %validator_id, %err, "Self-delivery of attestation failed")
                     });
@@ -451,7 +451,7 @@ impl BlockChainServer {
         }
     }
 
-    fn on_gossip_attestation(&mut self, attestation: SignedAttestation) {
+    fn on_gossip_attestation(&mut self, attestation: &SignedAttestation) {
         if !self.is_aggregator {
             warn!("Received unaggregated attestation but node is not an aggregator");
             return;
@@ -516,7 +516,7 @@ impl Handler<NewBlock> for BlockChainServer {
 
 impl Handler<NewAttestation> for BlockChainServer {
     async fn handle(&mut self, msg: NewAttestation, _ctx: &Context<Self>) {
-        self.on_gossip_attestation(msg.attestation);
+        self.on_gossip_attestation(&msg.attestation);
     }
 }
 

crates/blockchain/src/store.rs

@@ -532,12 +532,12 @@ pub fn on_tick(
 /// at interval 2. Only aggregator nodes receive unaggregated gossip attestations.
 pub fn on_gossip_attestation(
     store: &mut Store,
-    signed_attestation: SignedAttestation,
+    signed_attestation: &SignedAttestation,
 ) -> Result<(), StoreError> {
     let validator_id = signed_attestation.validator_id;
     let attestation = Attestation {
         validator_id,
-        data: signed_attestation.data,
+        data: signed_attestation.data.clone(),
     };
     validate_attestation_data(store, &attestation.data)
         .inspect_err(|_| metrics::inc_attestations_invalid())?;