loadtest: add BaseUni noop implementation

Since we're going to use the SimpleSyncer from the universe package, we
need to make sure it remains lightweight and doesn't persist anything.
That's why we create an empty implementation of the local diff engine
and registrar, which performs a noop on all its methods, except for the
RootNode call, which returns an empty leaf.

Author: GeorgeTsagk

itest/loadtest/utils.go

@@ -14,14 +14,17 @@ import (
 	"github.com/btcsuite/btcd/rpcclient"
 	tap "github.com/lightninglabs/taproot-assets"
 	"github.com/lightninglabs/taproot-assets/cmd/commands"
+	"github.com/lightninglabs/taproot-assets/fn"
 	"github.com/lightninglabs/taproot-assets/itest"
+	"github.com/lightninglabs/taproot-assets/mssmt"
 	"github.com/lightninglabs/taproot-assets/taprpc"
 	"github.com/lightninglabs/taproot-assets/taprpc/assetwalletrpc"
 	"github.com/lightninglabs/taproot-assets/taprpc/mintrpc"
 	"github.com/lightninglabs/taproot-assets/taprpc/rfqrpc"
 	tchrpc "github.com/lightninglabs/taproot-assets/taprpc/tapchannelrpc"
 	"github.com/lightninglabs/taproot-assets/taprpc/tapdevrpc"
 	"github.com/lightninglabs/taproot-assets/taprpc/universerpc"
+	"github.com/lightninglabs/taproot-assets/universe"
 	"github.com/lightningnetwork/lnd/lntest/rpc"
 	"github.com/lightningnetwork/lnd/macaroons"
 	"github.com/stretchr/testify/require"
@@ -311,3 +314,80 @@ func stringToAssetType(t string) taprpc.AssetType {
 		return taprpc.AssetType_NORMAL
 	}
 }
+
+// noopBaseUni is a dummy implementation of the universe.DiffEngine and
+// universe.LocalRegistrar interfaces. This is meant to be used by the simple
+// syncer used in the sync loadtest. As we don't care about persistence and we
+// always want to do a full sync, we always return an empty root node to trigger
+// a sync.
+type noopBaseUni struct{}
+
+// RootNode returns the root node of the base universe corresponding to the
+// passed ID.
+func (n noopBaseUni) RootNode(ctx context.Context,
+	id universe.Identifier) (universe.Root, error) {
+
+	return universe.Root{
+		Node: mssmt.EmptyLeafNode,
+	}, nil
+}
+
+// RootNodes returns the set of root nodes for all known base universes assets.
+func (n noopBaseUni) RootNodes(ctx context.Context,
+	q universe.RootNodesQuery) ([]universe.Root, error) {
+
+	return nil, nil
+}
+
+// MultiverseRoot returns the root node of the multiverse for the specified
+// proof type. If the given list of universe IDs is non-empty, then the root
+// will be calculated just for those universes.
+func (n *noopBaseUni) MultiverseRoot(ctx context.Context,
+	proofType universe.ProofType,
+	filterByIDs []universe.Identifier) (fn.Option[universe.MultiverseRoot],
+	error) {
+
+	return fn.None[universe.MultiverseRoot](), nil
+}
+
+// UpsertProofLeaf attempts to upsert a proof for an asset issuance or transfer
+// event. This method will return an error if the passed proof is invalid. If
+// the leaf is already known, then no action is taken and the existing
+// commitment proof returned.
+func (n noopBaseUni) UpsertProofLeaf(ctx context.Context,
+	id universe.Identifier, key universe.LeafKey,
+	leaf *universe.Leaf) (*universe.Proof, error) {
+
+	return nil, nil
+}
+
+// UpsertProofLeafBatch inserts a batch of proof leaves within the target
+// universe tree. We assume the proofs within the batch have already been
+// checked that they don't yet exist in the local database.
+func (n noopBaseUni) UpsertProofLeafBatch(ctx context.Context,
+	items []*universe.Item) error {
+
+	return nil
+}
+
+// Close closes the noopBaseUni, stopping all goroutines and freeing all
+// resources.
+func (n noopBaseUni) Close() error {
+	return nil
+}
+
+// FetchProofLeaf attempts to fetch a proof leaf for the target leaf key
+// and given a universe identifier (assetID/groupKey).
+func (n noopBaseUni) FetchProofLeaf(ctx context.Context, id universe.Identifier,
+	key universe.LeafKey) ([]*universe.Proof, error) {
+
+	return nil, nil
+}
+
+// UniverseLeafKeys returns the set of leaf keys known for the specified
+// universe identifier.
+func (n noopBaseUni) UniverseLeafKeys(ctx context.Context,
+	q universe.UniverseLeafKeysQuery) ([]universe.LeafKey, error) {
+
+	return nil, nil
+}