Ewma.hxx

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#ifndef _UTILS_EWMA_HXX_
#define _UTILS_EWMA_HXX_
 
#include <time.h>
#include <stdint.h>
 
class Ewma
{
public:
    Ewma(float alpha = 0.8)
        : alpha_(alpha)
    {
    }
 
    void add_absolute(uint32_t offset)
    {
        add_diff(offset - lastOffset_);
        lastOffset_ = offset;
    }
 
    void add_diff(uint32_t bytes)
    {
        long long t = current_time();
        if (lastMeasurementTimeNsec_)
        {
            float spd = bytes * 1e9 / (t - lastMeasurementTimeNsec_);
            if (avg_)
            {
                avg_ = avg_ * alpha_ + spd * (1 - alpha_);
            }
            else
            {
                avg_ = spd;
            }
        }
        lastMeasurementTimeNsec_ = t;
    }
 
    float avg()
    {
        return avg_;
    }
 
private:
    long long current_time()
    {
        long long t;
#ifdef __linux__
        struct timespec ts;
        clock_gettime(CLOCK_REALTIME, &ts);
        t = ts.tv_sec * 1000000000;
        t += ts.tv_nsec;
#else
        t = os_get_time_monotonic();
#endif
        return t;
    }
 
    float alpha_;    
    float avg_{0.0}; 
    long long lastMeasurementTimeNsec_{0};
    uint32_t lastOffset_{0};
};
 
class AbsEwma
{
public:
    AbsEwma(float alpha)
        : alpha_(alpha)
    {
    }
 
    void set_alpha(float alpha)
    {
        alpha_ = alpha;
    }
 
    void add_value(float value)
    {
        if (avg_)
        {
            avg_ = avg_ * alpha_ + value * (1 - alpha_);
        }
        else
        {
            avg_ = value;
        }
    }
 
    void reset_state(float value)
    {
        avg_ = value;
    }
 
    float avg()
    {
        return avg_;
    }
 
    float alpha_;    
    float avg_{0.0}; 
};
 
#endif // _UTILS_EWMA_HXX_