folly::EventBase::SmoothLoopTime Class Reference

#include <EventBase.h>

Public Member Functions
	SmoothLoopTime (std::chrono::microseconds timeInterval)
void	setTimeInterval (std::chrono::microseconds timeInterval)
void	reset (double value=0.0)
void	addSample (std::chrono::microseconds total, std::chrono::microseconds busy)
double	get () const
void	dampen (double factor)

Private Attributes
double	expCoeff_
double	value_
std::chrono::microseconds	buffer_time_ {0}
std::chrono::microseconds	busy_buffer_ {0}
std::size_t	buffer_cnt_ {0}

Static Private Attributes
static constexpr std::chrono::milliseconds	buffer_interval_ {10}

Detailed Description

Definition at line 553 of file EventBase.h.

Constructor & Destructor Documentation

folly::EventBase::SmoothLoopTime::SmoothLoopTime ( std::chrono::microseconds  timeInterval )

inlineexplicit

Definition at line 555 of file EventBase.h.

References folly::value().

        : expCoeff_(-1.0 / timeInterval.count()), value_(0.0) {
      VLOG(11) << "expCoeff_ " << expCoeff_ << " " << __PRETTY_FUNCTION__;
    }

Member Function Documentation

void folly::EventBase::SmoothLoopTime::addSample	(	std::chrono::microseconds	total,
		std::chrono::microseconds	busy
	)

Definition at line 671 of file EventBase.cpp.

Referenced by folly::EventBase::loopBody().

                                {
  if ((buffer_time_ + total) > buffer_interval_ && buffer_cnt_ > 0) {
    // See https://en.wikipedia.org/wiki/Exponential_smoothing for
    // more info on this calculation.
    double coeff = exp(buffer_time_.count() * expCoeff_);
    value_ =
        value_ * coeff + (1.0 - coeff) * (busy_buffer_.count() / buffer_cnt_);
    buffer_time_ = std::chrono::microseconds{0};
    busy_buffer_ = std::chrono::microseconds{0};
    buffer_cnt_ = 0;
  }
  buffer_time_ += total;
  busy_buffer_ += busy;
  buffer_cnt_++;
}

void folly::EventBase::SmoothLoopTime::dampen ( double  factor )

inline

Definition at line 574 of file EventBase.h.

Referenced by folly::EventBase::loopBody().

                               {
      value_ *= factor;
    }

double folly::EventBase::SmoothLoopTime::get ( ) const

inline

Definition at line 567 of file EventBase.h.

Referenced by folly::EventBase::loopBody().

                       {
      // Add the outstanding buffered times linearly, to avoid
      // expensive exponentiation
      auto lcoeff = buffer_time_.count() * -expCoeff_;
      return value_ * (1.0 - lcoeff) + lcoeff * busy_buffer_.count();
    }

void folly::EventBase::SmoothLoopTime::reset

(

double

value = 0.0

)

Definition at line 667 of file EventBase.cpp.

References folly::value().

Referenced by folly::EventBase::resetLoadAvg().

                                                {
  value_ = value;
}

void folly::EventBase::SmoothLoopTime::setTimeInterval

(

std::chrono::microseconds

timeInterval

)

Definition at line 661 of file EventBase.cpp.

Referenced by folly::EventBase::setLoadAvgMsec().

                                        {
  expCoeff_ = -1.0 / timeInterval.count();
  VLOG(11) << "expCoeff_ " << expCoeff_ << " " << __PRETTY_FUNCTION__;
}

Member Data Documentation

std::size_t folly::EventBase::SmoothLoopTime::buffer_cnt_ {0}

private

Definition at line 583 of file EventBase.h.

constexpr std::chrono::milliseconds folly::EventBase::SmoothLoopTime::buffer_interval_ {10}

staticprivate

Definition at line 584 of file EventBase.h.

Referenced by folly::EventBase::getEventBase().

std::chrono::microseconds folly::EventBase::SmoothLoopTime::buffer_time_ {0}

private

Definition at line 581 of file EventBase.h.

std::chrono::microseconds folly::EventBase::SmoothLoopTime::busy_buffer_ {0}

private

Definition at line 582 of file EventBase.h.

double folly::EventBase::SmoothLoopTime::expCoeff_

private

Definition at line 579 of file EventBase.h.

double folly::EventBase::SmoothLoopTime::value_

private

Definition at line 580 of file EventBase.h.

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The documentation for this class was generated from the following files:

• proxygen/folly/folly/io/async/EventBase.h
• proxygen/folly/folly/io/async/EventBase.cpp