internal

type RWConnector struct {
	QueryIn  chan *RWQueryMessage
	QueryOut chan *RWQueryMessage

	ExecIn  chan *RWExecMessage
	ExecOut chan *RWExecMessage

	RollbackIn chan struct{}
	CommitIn   chan struct{}
	Errors     chan error // only for starting, commit and rollback

	Ready chan struct{}
}

type RWExecMessage struct {
	Ctx  context.Context   // in
	Stmt spanner.Statement // in

	Rows  int64 // out
	Error error // out
}

type RWQueryMessage struct {
	Ctx  context.Context   // in
	Stmt spanner.Statement // in

	It *spanner.RowIterator // out
}