fix memdb snapshot

integ_test.go

@@ -318,7 +318,7 @@ func TestWatchUpdate(t *testing.T) {
 	watchSetPrefix.Add(watch)
 
 	// Write to a snapshot.
-	snap := db.Snapshot(true)
+	snap := db.Snapshot()
 	txn2 := snap.Txn(true) // write
 	noErr(t, txn2.Delete("people", raw))
 	txn2.Commit()

memdb.go

@@ -63,10 +63,10 @@ func (db *MemDB) DBSchema() *DBSchema {
 }
 
 // getRoot is used to do an atomic load of the root pointer
-func (db *MemDB) getRoot(clone bool) *iradix.Tree {
+func (db *MemDB) getRoot(snap bool) *iradix.Tree {
 	root := (*iradix.Tree)(atomic.LoadPointer(&db.root))
-	if clone {
-		root = root.Clone()
+	if snap {
+		root = root.Snapshot()
 	}
 	return root
 }
@@ -91,10 +91,10 @@ func (db *MemDB) Txn(write bool) *Txn {
 // If MemDB is storing reference-based values (pointers, maps, slices, etc.),
 // the Snapshot will not deep copy those values. Therefore, it is still unsafe
 // to modify any inserted values in either DB.
-func (db *MemDB) Snapshot(write bool) *MemDB {
+func (db *MemDB) Snapshot() *MemDB {
 	clone := &MemDB{
 		schema:  db.schema,
-		root:    unsafe.Pointer(db.getRoot(write)),
+		root:    unsafe.Pointer(db.getRoot(true)),
 		primary: false,
 	}
 	return clone

memdb_test.go

@@ -58,7 +58,7 @@ func TestMemDB_Snapshot(t *testing.T) {
 	txn.Commit()
 
 	// Clone the db
-	db2 := db.Snapshot(true)
+	db2 := db.Snapshot()
 
 	// Remove the object
 	txn = db.Txn(true)
@@ -101,7 +101,7 @@ func BenchmarkMemDB_Snapshot(b *testing.B) {
 		txn.Commit()
 	}
 	// Clone the db
-	snap := db.Snapshot(false)
+	snap := db.Snapshot()
 	fmt.Println(snap.getRoot(false).Len())
 	fmt.Println(counter)
 }

txn.go

@@ -71,7 +71,9 @@ func (txn *Txn) readableIndex(table, index string) *iradix.Txn {
 	// Create a read transaction
 	path := indexPath(table, index)
 	raw, _ := txn.rootTxn.Get(path)
-	indexTxn := raw.(*iradix.Tree).Txn()
+	tree := raw.(*iradix.Tree)
+	tree.Root().SetSnapShotNode(txn.rootTxn.Root().GetSnapshotNode())
+	indexTxn := tree.Txn()
 	return indexTxn
 }
 
@@ -92,7 +94,9 @@ func (txn *Txn) writableIndex(table, index string) *iradix.Txn {
 	// Start a new transaction
 	path := indexPath(table, index)
 	raw, _ := txn.rootTxn.Get(path)
-	indexTxn := raw.(*iradix.Tree).Txn()
+	tree := raw.(*iradix.Tree)
+	tree.Root().SetSnapShotNode(txn.rootTxn.Root().GetSnapshotNode())
+	indexTxn := tree.Txn()
 
 	// If we are the primary DB, enable mutation tracking. Snapshots should
 	// not notify, otherwise we will trigger watches on the primary DB when