add SupportsVisitor in the markset env interface

blockstore/splitstore/markset.go

@@ -34,6 +34,8 @@ type MarkSetEnv interface {
 	// CreateVisitor is like Create, but returns a wider interface that supports atomic visits.
 	// It may not be supported by some markset types (e.g. bloom).
 	CreateVisitor(name string, sizeHint int64) (MarkSetVisitor, error)
+	// SupportsVisitor returns true if the marksets created by this environment support the visitor interface.
+	SupportsVisitor() bool
 	Close() error
 }
 

blockstore/splitstore/markset_badger.go

@@ -76,6 +76,8 @@ func (e *BadgerMarkSetEnv) CreateVisitor(name string, sizeHint int64) (MarkSetVi
 	return e.create(name, sizeHint)
 }
 
+func (e *BadgerMarkSetEnv) SupportsVisitor() bool { return true }
+
 func (e *BadgerMarkSetEnv) Close() error {
 	return os.RemoveAll(e.path)
 }

blockstore/splitstore/markset_bloom.go

@@ -57,6 +57,8 @@ func (e *BloomMarkSetEnv) CreateVisitor(name string, sizeHint int64) (MarkSetVis
 	return nil, xerrors.Errorf("bloom mark set does not support visitors due to false positives")
 }
 
+func (e *BloomMarkSetEnv) SupportsVisitor() bool { return false }
+
 func (e *BloomMarkSetEnv) Close() error {
 	return nil
 }

blockstore/splitstore/markset_map.go

@@ -38,6 +38,8 @@ func (e *MapMarkSetEnv) CreateVisitor(name string, sizeHint int64) (MarkSetVisit
 	return e.create(name, sizeHint)
 }
 
+func (e *MapMarkSetEnv) SupportsVisitor() bool { return true }
+
 func (e *MapMarkSetEnv) Close() error {
 	return nil
 }

blockstore/splitstore/splitstore.go

@@ -173,6 +173,10 @@ func Open(path string, ds dstore.Datastore, hot, cold bstore.Blockstore, cfg *Co
 		return nil, err
 	}
 
+	if !markSetEnv.SupportsVisitor() {
+		return nil, xerrors.Errorf("markset type does not support atomic visitors")
+	}
+
 	// and now we can make a SplitStore
 	ss := &SplitStore{
 		cfg:        cfg,