fix: update Solana last scanned block more frequently (#3314)

* update Solana last scanned block more frequently

* add changelog entry

* update slot only if RPC returns nil error

* update slot only if RPC returns nil error

---------

Co-authored-by: Christopher Fuka <[email protected]>

changelog.md

@@ -28,6 +28,7 @@
 * [3253](https://github.com/zeta-chain/node/pull/3253) - fix solana inbound version 0 queries and move tss keysign prior to relayer key checking
 * [3278](https://github.com/zeta-chain/node/pull/3278) - enforce checksum format for asset address in ZRC20
 * [3289](https://github.com/zeta-chain/node/pull/3289) - remove all dynamic peer discovery (zetaclient)
+* [3314](https://github.com/zeta-chain/node/pull/3314) - update `last_scanned_block_number` metrics more frequently for Solana chain
 
 ## v23.0.0
 

zetaclient/chains/solana/observer/inbound.go

@@ -81,14 +81,26 @@ func (ob *Observer) ObserveInbound(ctx context.Context) error {
 		ob.WithLastTxScanned(lastSig.String())
 	}
 
+	// query last finalized slot
+	lastSlot, errSlot := ob.solClient.GetSlot(ctx, rpc.CommitmentFinalized)
+	if errSlot != nil {
+		ob.Logger().Inbound.Err(errSlot).Msg("unable to get last slot")
+	}
+
 	// get all signatures for the gateway address since last scanned signature
 	lastSig := solana.MustSignatureFromBase58(ob.LastTxScanned())
 	signatures, err := solanarpc.GetSignaturesForAddressUntil(ctx, ob.solClient, ob.gatewayID, lastSig, pageLimit)
 	if err != nil {
 		ob.Logger().Inbound.Err(err).Msg("error GetSignaturesForAddressUntil")
 		return err
 	}
-	if len(signatures) > 0 {
+
+	// update metrics if no new signatures found
+	if len(signatures) == 0 {
+		if errSlot == nil {
+			ob.WithLastBlockScanned(lastSlot)
+		}
+	} else {
 		ob.Logger().Inbound.Info().Msgf("ObserveInbound: got %d signatures for chain %d", len(signatures), chainID)
 	}