RateLimiter.hpp

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// ======================================================================
// \title  RateLimiter.hpp
// \author vwong
// \brief  hpp file for a rate limiter utility class
//
// \copyright
// Copyright (C) 2009-2020 California Institute of Technology.
//
// ALL RIGHTS RESERVED. United States Government Sponsorship
// acknowledged.
// ======================================================================

#ifndef RateLimiter_HPP
#define RateLimiter_HPP

#include <Fw/FPrimeBasicTypes.hpp>
#include <Fw/Time/Time.hpp>

namespace Utils {

class RateLimiter {
  public:
    // Construct with defined cycles
    RateLimiter(U32 counterCycle, U32 timeCycle);

    // Construct with cycles set to 0
    RateLimiter();

  public:
    // Adjust cycles at run-time
    void setCounterCycle(U32 counterCycle);
    void setTimeCycle(U32 timeCycle);

    // Main point of entry
    //
    // It will only factor in counter or time, whichever one has a cycle defined
    //
    // If both are defined, then satisfying _either_ one will work
    // e.g. I want to trigger only once every X times or once every Y
    // seconds, whichever comes first
    //
    // The argument-less version is a shorthand for counter-only RateLimiters
    // If a time cycle is defined but the argument-less version is called,
    // RateLimiter assumes the client forgot to supply a time, and asserts
    //
    bool trigger(Fw::Time time);
    bool trigger();

    // Manual state adjustments, if necessary
    void reset();
    void resetCounter();
    void resetTime();
    void setCounter(U32);
    void setTime(Fw::Time time);

  private:
    // Helper functions to update each independently
    bool shouldCounterTrigger();
    bool shouldTimeTrigger(Fw::Time time);
    void updateCounter(bool triggered);
    void updateTime(bool triggered, Fw::Time time);

  private:
    // parameters
    U32 m_counterCycle;
    U32 m_timeCycle;

    // state
    U32 m_counter;
    Fw::Time m_time;
    bool m_timeAtNegativeInfinity;
};

}  // end namespace Utils

#endif