Smooth rate limiter (C++)

rate_limiter.cpp

// Smooth rate limiter based on token bucket
// Author: Max Schwarz <[email protected]>

#include "rate_limiter.h"

#include <ros/time.h>

class RateLimiter::Private
{
public:
    Private(float rate)
     : rate(rate)
    {}

    ros::Time lastTime{0};
    float bucket = 0;
    float rate;
};

RateLimiter::RateLimiter(float rate)
 : m_d{std::make_unique<Private>(rate)}
{
}

RateLimiter::~RateLimiter()
{
}

bool RateLimiter::step()
{
    ros::Time now = ros::Time::now();
    if(m_d->lastTime == ros::Time(0))
    {
        m_d->lastTime = now;
        return true;
    }
    else
    {
        // Basic token bucket algorithm for rate limiting
        ros::Duration elapsed = now - m_d->lastTime;
        m_d->lastTime = now;

        m_d->bucket = std::min(2.0f,
            m_d->bucket + static_cast<float>(elapsed.toSec()) * m_d->rate
        );

        if(m_d->bucket < 1.0f)
            return false;

        m_d->bucket -= 1.0f;
        return true;
    }
}

rate_limiter.h

// Smooth rate limiter based on token bucket
// Author: Max Schwarz <[email protected]>

#ifndef RATE_LIMITER_H
#define RATE_LIMITER_H

#include <memory>

class RateLimiter
{
public:
    explicit RateLimiter(float rate);
    ~RateLimiter();

    //! Returns true if the event should be accepted
    bool step();

private:
    class Private;
    std::unique_ptr<Private> m_d;
};

#endif