79 lines
2.1 KiB
C++
79 lines
2.1 KiB
C++
#ifndef STAR_TICK_RATE_MONITOR_HPP
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#define STAR_TICK_RATE_MONITOR_HPP
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#include "StarList.hpp"
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namespace Star {
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// Monitors the rate at which 'tick()' is called in wall-clock seconds.
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class TickRateMonitor {
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public:
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// 'window' controls the dropoff at which 'rate' will approach zero if tick
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// is not called, measured in seconds.
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TickRateMonitor(double window);
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double window() const;
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// Resets to a zero tick-rate state
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void reset();
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// Ticks the given number of times, returns the current rate.
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double tick(unsigned count = 1);
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// Returns the rate as of the *current* time, not the time of the last tick.
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double rate() const;
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private:
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void dropOff(double currentTime);
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double m_window;
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double m_lastTick;
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double m_ticks;
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};
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// Helps tick at as close as possible to a given tick rate
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class TickRateApproacher {
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public:
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TickRateApproacher(double targetTickRate, double window);
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// The TickRateMonitor window influences how long the TickRateApproacher will
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// try and speed up or slow down the tick rate to match the target tick rate.
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// It should be chosen so that it is not so short that the actual target rate
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// drifts, but not too long so that the rate returns to normal quickly enough
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// with outliers.
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double window() const;
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// Setting the window to a new value will reset the TickRateApproacher
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void setWindow(double window);
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double targetTickRate() const;
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void setTargetTickRate(double targetTickRate);
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// Resets such that the current tick rate is assumed to be perfectly at the
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// target.
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void reset();
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double tick(unsigned count = 1);
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double rate() const;
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// How many ticks we currently should perform, so that if each tick happened
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// instantly, we would be as close to the target tick rate as possible. If
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// we are ahead, may be negative.
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double ticksBehind();
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// The negative of ticksBehind, is positive for how many ticks ahead we
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// currently are.
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double ticksAhead();
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// How much spare time we have until the tick rate will begin to be behind
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// the target tick rate.
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double spareTime();
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private:
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TickRateMonitor m_tickRateMonitor;
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double m_targetTickRate;
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};
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};
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#endif
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