Revert "Fix ListValidatorBalances for v0.11 (#5458)"

This reverts commit 3763a8c.

beacon-chain/rpc/beacon/validators.go

@@ -30,43 +30,59 @@ func (bs *Server) ListValidatorBalances(
 			req.PageSize, flags.Get().MaxPageSize)
 	}
 
-	currentEpoch := helpers.SlotToEpoch(bs.GenesisTimeFetcher.CurrentSlot())
-	requestedEpoch := currentEpoch
+	res := make([]*ethpb.ValidatorBalances_Balance, 0)
+	filtered := map[uint64]bool{} // Track filtered validators to prevent duplication in the response.
+
+	headState, err := bs.HeadFetcher.HeadState(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, "Could not get head state")
+	}
+
+	var requestingGenesis bool
+	var epoch uint64
 	switch q := req.QueryFilter.(type) {
 	case *ethpb.ListValidatorBalancesRequest_Epoch:
-		requestedEpoch = q.Epoch
+		epoch = q.Epoch
 	case *ethpb.ListValidatorBalancesRequest_Genesis:
-		requestedEpoch = 0
+		requestingGenesis = q.Genesis
 	default:
-		requestedEpoch = currentEpoch
+		epoch = helpers.CurrentEpoch(headState)
 	}
 
-	if requestedEpoch > currentEpoch {
+	var balances []uint64
+	validators := headState.Validators()
+	if requestingGenesis || epoch < helpers.CurrentEpoch(headState) {
+		balances, err = bs.BeaconDB.ArchivedBalances(ctx, epoch)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "Could not retrieve balances for epoch %d", epoch)
+		}
+		if balances == nil {
+			return nil, status.Errorf(
+				codes.NotFound,
+				"Could not retrieve data for epoch %d, perhaps --archive in the running beacon node is disabled",
+				0,
+			)
+		}
+	} else if epoch == helpers.CurrentEpoch(headState) {
+		balances = headState.Balances()
+	} else {
+		// Otherwise, we are requesting data from the future and we return an error.
 		return nil, status.Errorf(
 			codes.InvalidArgument,
 			"Cannot retrieve information about an epoch in the future, current epoch %d, requesting %d",
-			currentEpoch,
-			requestedEpoch,
+			helpers.CurrentEpoch(headState),
+			epoch,
 		)
 	}
-	res := make([]*ethpb.ValidatorBalances_Balance, 0)
-	filtered := map[uint64]bool{} // Track filtered validators to prevent duplication in the response.
 
-	requestedState, err := bs.StateGen.StateBySlot(ctx, helpers.StartSlot(requestedEpoch))
-	if err != nil {
-		return nil, status.Errorf(codes.Internal, "Could not get state")
-	}
-
-	validators := requestedState.Validators()
-	balances := requestedState.Balances()
 	balancesCount := len(balances)
 	for _, pubKey := range req.PublicKeys {
 		// Skip empty public key.
 		if len(pubKey) == 0 {
 			continue
 		}
 		pubkeyBytes := bytesutil.ToBytes48(pubKey)
-		index, ok := requestedState.ValidatorIndexByPubkey(pubkeyBytes)
+		index, ok := headState.ValidatorIndexByPubkey(pubkeyBytes)
 		if !ok {
 			return nil, status.Errorf(codes.NotFound, "Could not find validator index for public key %#x", pubkeyBytes)
 		}
@@ -88,6 +104,10 @@ func (bs *Server) ListValidatorBalances(
 
 	for _, index := range req.Indices {
 		if int(index) >= len(balances) {
+			if epoch <= helpers.CurrentEpoch(headState) {
+				return nil, status.Errorf(codes.OutOfRange, "Validator index %d does not exist in historical balances",
+					index)
+			}
 			return nil, status.Errorf(codes.OutOfRange, "Validator index %d >= balance list %d",
 				index, len(balances))
 		}
@@ -110,7 +130,7 @@ func (bs *Server) ListValidatorBalances(
 	// Otherwise, attempting to paginate 0 balances below would result in an error.
 	if balancesCount == 0 {
 		return &ethpb.ValidatorBalances{
-			Epoch:         requestedEpoch,
+			Epoch:         epoch,
 			Balances:      make([]*ethpb.ValidatorBalances_Balance, 0),
 			TotalSize:     int32(0),
 			NextPageToken: strconv.Itoa(0),
@@ -129,23 +149,23 @@ func (bs *Server) ListValidatorBalances(
 	if len(req.Indices) == 0 && len(req.PublicKeys) == 0 {
 		// Return everything.
 		for i := start; i < end; i++ {
-			pubkey := requestedState.PubkeyAtIndex(uint64(i))
+			pubkey := headState.PubkeyAtIndex(uint64(i))
 			res = append(res, &ethpb.ValidatorBalances_Balance{
 				PublicKey: pubkey[:],
 				Index:     uint64(i),
 				Balance:   balances[i],
 			})
 		}
 		return &ethpb.ValidatorBalances{
-			Epoch:         requestedEpoch,
+			Epoch:         epoch,
 			Balances:      res,
 			TotalSize:     int32(balancesCount),
 			NextPageToken: nextPageToken,
 		}, nil
 	}
 
 	return &ethpb.ValidatorBalances{
-		Epoch:         requestedEpoch,
+		Epoch:         epoch,
 		Balances:      res[start:end],
 		TotalSize:     int32(balancesCount),
 		NextPageToken: nextPageToken,