addblock: Fix blockchain initialization.

This updates the addblock command to create UtxoBackend and UtxoCache
instances, which are required for initializing the blockchain.

cmd/addblock/addblock.go

@@ -85,6 +85,15 @@ func realMain() error {
 	}
 	defer db.Close()
 
+	// Load the UTXO database.
+	utxoDb, err := blockchain.LoadUtxoDB(context.Background(), activeNetParams,
+		cfg.DataDir)
+	if err != nil {
+		log.Errorf("Failed to load UTXO database: %v", err)
+		return err
+	}
+	defer utxoDb.Close()
+
 	fi, err := os.Open(cfg.InFile)
 	if err != nil {
 		log.Errorf("Failed to open file %v: %v", cfg.InFile, err)
@@ -96,7 +105,7 @@ func realMain() error {
 	// The done channel returned from start will contain an error if
 	// anything went wrong.
 	ctx, cancel := context.WithCancel(context.Background())
-	importer, err := newBlockImporter(ctx, db, fi, cancel)
+	importer, err := newBlockImporter(ctx, db, utxoDb, fi, cancel)
 	if err != nil {
 		log.Errorf("Failed create block importer: %v", err)
 		return err

cmd/addblock/import.go

@@ -20,6 +20,7 @@ import (
 	"github.com/decred/dcrd/database/v3"
 	"github.com/decred/dcrd/dcrutil/v4"
 	"github.com/decred/dcrd/wire"
+	"github.com/syndtr/goleveldb/leveldb"
 )
 
 var zeroHash = chainhash.Hash{}
@@ -307,17 +308,27 @@ func (bi *blockImporter) Import(ctx context.Context) chan *importResults {
 
 // newBlockImporter returns a new importer for the provided file reader seeker
 // and database.
-func newBlockImporter(ctx context.Context, db database.DB, r io.ReadSeeker, cancel context.CancelFunc) (*blockImporter, error) {
+func newBlockImporter(ctx context.Context, db database.DB, utxoDb *leveldb.DB, r io.ReadSeeker, cancel context.CancelFunc) (*blockImporter, error) {
 	subber := indexers.NewIndexSubscriber(ctx)
 	go subber.Run(ctx)
 
+	// Instantiate a UTXO backend and UTXO cache.
+	utxoBackend := blockchain.NewLevelDbUtxoBackend(utxoDb)
+	utxoCache := blockchain.NewUtxoCache(&blockchain.UtxoCacheConfig{
+		Backend:      utxoBackend,
+		FlushBlockDB: db.Flush,
+		MaxSize:      100 * 1024 * 1024, // 100 MiB
+	})
+
 	chain, err := blockchain.New(context.Background(),
 		&blockchain.Config{
 			DB:              db,
 			ChainParams:     activeNetParams,
 			Checkpoints:     activeNetParams.Checkpoints,
 			TimeSource:      blockchain.NewMedianTime(),
 			IndexSubscriber: subber,
+			UtxoBackend:     blockchain.NewLevelDbUtxoBackend(utxoDb),
+			UtxoCache:       utxoCache,
 		})
 	if err != nil {
 		return nil, err