Main loop for the filter

[HandsomeDragon3]

As a function is written as:

void GpsIns::loop()
{
//m.lock();
std::lock_guardstd::mutex lock(m);
set_data();
filter->process(*_sensor_data);
_prev_gps_counter = _gpscounter;
//m.unlock();
}

The function above is being introduced as "Main loop for the filter". I am confused about the functions:read_gps_data, read_imu_data, read_encoders seem not working here ,and some counters are forgot to plus "1". Is there some work should be done by ourselves and you simplify the main loop here? Thanks, just too confused.