src/server/pkg/hashtree/db.go
func NewDBHashTree(storageRoot string) (HashTree, error) {
	file := dbFile(storageRoot)
	if err := os.MkdirAll(pathlib.Dir(file), 0777); err != nil {
		return nil, err
	}
	result, err := newDBHashTree(file)
	if err != nil {
		return nil, err
	}
	if err := result.PutDir("/"); err != nil {
		return nil, err
	}
	return result, err
}
func NewDBHashTree(storageRoot string) (HashTree, error) {
	file := dbFile(storageRoot)
	if err := os.MkdirAll(pathlib.Dir(file), 0777); err != nil {
		return nil, err
	}
	result, err := newDBHashTree(file)
	if err != nil {
		return nil, err
	}
	if err := result.PutDir("/"); err != nil {
		return nil, err
	}
	return result, err
}
// NewDBHashTree creates a database (bolt) backed hashtree.