// Mutex protecting <queued_data> and <queued_data_last_starting_point>.
// Note that if you want to hold both this and the owning server's
// <mutex> you will need to take <mutex> before this one.
// Mutex protecting <queued_data> and <queued_data_last_starting_point>.
// Note that if you want to hold both this and the owning server's
// <mutex> you will need to take <mutex> before this one.