triedb/pathdb: make Recoverable check cheaper

triedb/pathdb/database.go

@@ -543,15 +543,15 @@ func (db *Database) Recoverable(root common.Hash) bool {
 	if db.stateFreezer == nil {
 		return false
 	}
-	// Ensure the requested state is a canonical state and all state
-	// histories in range [id+1, dl.ID] are present and complete.
-	return checkStateHistories(db.stateFreezer, *id+1, dl.stateID()-*id, func(m *meta) error {
-		if m.parent != root {
-			return errors.New("unexpected state history")
-		}
-		root = m.root
-		return nil
-	}) == nil
+	blob := rawdb.ReadStateHistoryMeta(db.stateFreezer, *id+1)
+	if len(blob) == 0 {
+		return false // pruned from the tail or otherwise unavailable
+	}
+	var m meta
+	if err := m.decode(blob); err != nil {
+		return false
+	}
+	return m.parent == root
 }
 
 // Close closes the trie database and the held freezer.

triedb/pathdb/history_state.go

@@ -612,30 +612,3 @@ func writeStateHistory(writer ethdb.AncientWriter, dl *diffLayer) error {
 
 	return nil
 }
-
-// checkStateHistories retrieves a batch of metadata objects with the specified
-// range and performs the callback on each item.
-func checkStateHistories(reader ethdb.AncientReader, start, count uint64, check func(*meta) error) error {
-	for count > 0 {
-		number := count
-		if number > 10000 {
-			number = 10000 // split the big read into small chunks
-		}
-		blobs, err := rawdb.ReadStateHistoryMetaList(reader, start, number)
-		if err != nil {
-			return err
-		}
-		for _, blob := range blobs {
-			var dec meta
-			if err := dec.decode(blob); err != nil {
-				return err
-			}
-			if err := check(&dec); err != nil {
-				return err
-			}
-		}
-		count -= uint64(len(blobs))
-		start += uint64(len(blobs))
-	}
-	return nil
-}