newLegacyNodeDB and support for pure-preimage mode

nodedb.go

@@ -90,10 +90,11 @@ type nodeDB struct {
 	legacyLatestVersion int64            // Latest version of nodeDB in legacy format.
 	nodeCache           cache.Cache      // Cache for nodes in the regular tree that consists of key-value pairs at any version.
 	fastNodeCache       cache.Cache      // Cache for nodes in the fast index that represents only key-value pairs at the latest version.
+	useLegacyFormat     bool
 }
 
 func newNodeDB(db dbm.DB, cacheSize int, opts Options, lg log.Logger) *nodeDB {
-	storeVersion, err := db.Get(metadataKeyFormat.Key([]byte(storageVersionKey)))
+	storeVersion, err := db.Get(metadataKeyFormat.Key(ibytes.UnsafeStrToBytes(storageVersionKey)))
 
 	if err != nil || storeVersion == nil {
 		storeVersion = []byte(defaultStorageVersionValue)
@@ -114,6 +115,34 @@ func newNodeDB(db dbm.DB, cacheSize int, opts Options, lg log.Logger) *nodeDB {
 	}
 }
 
+func newLegacyNodeDB(db dbm.DB, cacheSize int, opts Options, noStoreVersion bool, lg log.Logger) *nodeDB {
+	var storeVersion []byte
+	if noStoreVersion {
+		storeVersion = []byte(defaultStorageVersionValue)
+	} else {
+		var err error
+		storeVersion, err = db.Get(metadataKeyFormat.Key(ibytes.UnsafeStrToBytes(storageVersionKey)))
+		if err != nil || storeVersion == nil {
+			storeVersion = []byte(defaultStorageVersionValue)
+		}
+	}
+
+	return &nodeDB{
+		logger:              lg,
+		db:                  db,
+		batch:               NewBatchWithFlusher(db, opts.FlushThreshold),
+		opts:                opts,
+		firstVersion:        0,
+		latestVersion:       0, // initially invalid
+		legacyLatestVersion: 0,
+		nodeCache:           cache.New(cacheSize),
+		fastNodeCache:       cache.New(fastNodeCacheSize),
+		versionReaders:      make(map[int64]uint32, 8),
+		storageVersion:      string(storeVersion),
+		useLegacyFormat:     true,
+	}
+}
+
 // GetNode gets a node from memory or disk. If it is an inner node, it does not
 // load its children.
 // It is used for both formats of nodes: legacy and new.
@@ -209,7 +238,7 @@ func (ndb *nodeDB) SaveNode(node *Node) error {
 	ndb.mtx.Lock()
 	defer ndb.mtx.Unlock()
 
-	if node.nodeKey == nil {
+	if (node.nodeKey == nil && !node.isLegacy) || (node.hash == nil && node.isLegacy) {
 		return ErrNodeMissingNodeKey
 	}