adding NopTx helper to dialect

Reviewed By: a8m

Differential Revision: D16757886

fbshipit-source-id: bd50ed4eefd30b5ed617220e6ba5b65b66cad2f3

dialect/dialect.go

@@ -44,6 +44,19 @@ type Tx interface {
 	driver.Tx
 }
 
+type nopTx struct {
+	Driver
+}
+
+func (nopTx) Commit() error   { return nil }
+func (nopTx) Rollback() error { return nil }
+
+// NopTx returns a Tx with a no-op Commit / Rollback methods wrapping
+// the provided Driver d.
+func NopTx(d Driver) Tx {
+	return nopTx{d}
+}
+
 // DebugDriver is a driver that logs all driver operations.
 type DebugDriver struct {
 	Driver                      // underlying driver.

dialect/gremlin/driver.go

@@ -46,15 +46,9 @@ func (c *Driver) Query(ctx context.Context, query string, args, v interface{}) e
 }
 
 // Close is a nop close call. It should close the connection in case of WS client.
-func (c *Driver) Close() error { return nil }
+func (Driver) Close() error { return nil }
 
 // Tx returns a nop transaction.
-func (c *Driver) Tx(context.Context) (dialect.Tx, error) { return c, nil }
-
-// Commit is a nop commit.
-func (c *Driver) Commit() error { return nil }
-
-// Rollback is a nop rollback.
-func (c *Driver) Rollback() error { return nil }
+func (c *Driver) Tx(context.Context) (dialect.Tx, error) { return dialect.NopTx(c), nil }
 
 var _ dialect.Driver = (*Driver)(nil)