throttle::watch Class Reference

class for limiting process load. More...

#include <throttle.h>

Collaboration diagram for throttle::watch:

Public Member Functions
	watch (const std::string &name)
void	update (double units=1.0)
void	wait ()
template<typename T , class ... Types>
T	action (T(*f)(Types...), Types ... args)

Private Attributes
options::single< double >	desiredRate
options::single< double >	tau
options::single< double >	p
options::single< double >	i
double	rateIntegral
double	lastRate
clock_type::time_point	lastStop
std::mutex	updateMutex

Detailed Description

class for limiting process load.

Implemented as a limited PI-controller. Each instance creates it's own set of config options. The update() function tells the watch how much "rate" was produced just now, the wait() function will delay the current thread so that the desired rate will not be exceeded.

Definition at line 18 of file throttle.h.

Constructor & Destructor Documentation

watch()

throttle::watch::watch ( const std::string &  name )

inline

Definition at line 28 of file throttle.h.

                                    :
            desiredRate('\0', name + "-rate", "throttle rate for " + name, 0),
            tau('\0', name + "-tau", "time constant for " + name, 1),
            p('\0', name + "-p", "prop constant for " + name, 1),
            i('\0', name + "-i", "integral constant for " + name, 1),
            lastStop(clock_type::now()) {
        }

Member Function Documentation

action()

template<typename T , class ... Types>

T throttle::watch::action ( T(*)(Types...)  f, Types ...  args  )

inline

Definition at line 64 of file throttle.h.

                                                                                          {
            wait();
            auto result = f(args ...);
            update();
            return result;
        }

References f(), update(), and wait().

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update()

void throttle::watch::update ( double  units = 1.0 )

inline

Definition at line 35 of file throttle.h.

                                        {
            if (desiredRate == 0) {
                return;
            }
            std::unique_lock<decltype(updateMutex)> lock(updateMutex);
            auto now = clock_type::now();
            auto dt = std::chrono::duration_cast<std::chrono::duration<double>>(now - lastStop).count();
            auto factor = dt / tau;
            if (factor > 1) {
                factor = 1;
            }
            lastRate = units / dt * factor + (1 - factor) * lastRate;
            rateIntegral += (lastRate - desiredRate) * dt;
            lastStop = now;
        }

References desiredRate, lastRate, lastStop, rateIntegral, tau, and updateMutex.

Referenced by action(), inputHandler::davix::readerDavix::readBlock(), inputHandler::dcap::readerDcap::readBlock(), inputHandler::daosFs::readerDaosFs::readBlock(), inputHandler::libssh::readerLibssh::readBlock(), inputHandler::posixFile::readerPosixFile::readBlock(), outputHandler::davix::writerDavix::writeBlock(), outputHandler::dcap::writerDcap::writeBlock(), outputHandler::libssh::writerLibssh::writeBlock(), outputHandler::posixFile::writerPosixFile::writeBlock(), outputHandler::daosFs::writerDaosFs::writeBlock(), and throttle::action::~action().

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wait()

void throttle::watch::wait ( )

inline

Definition at line 50 of file throttle.h.

                    {
            if (desiredRate == 0) {
                return;
            }
            auto dRate = (lastRate - desiredRate) * p + rateIntegral * i;
            if (dRate <= 0) {
                return;
            }
            auto w = dRate / desiredRate;
            if (w > 1) {
                w = 1;
            }
            std::this_thread::sleep_for(std::chrono::duration<double>(w));
        }

References desiredRate, i, lastRate, p, and rateIntegral.

Referenced by action(), throttle::action::action(), inputHandler::davix::readerDavix::readBlock(), inputHandler::dcap::readerDcap::readBlock(), inputHandler::daosFs::readerDaosFs::readBlock(), inputHandler::libssh::readerLibssh::readBlock(), inputHandler::posixFile::readerPosixFile::readBlock(), outputHandler::davix::writerDavix::writeBlock(), outputHandler::dcap::writerDcap::writeBlock(), outputHandler::libssh::writerLibssh::writeBlock(), outputHandler::posixFile::writerPosixFile::writeBlock(), and outputHandler::daosFs::writerDaosFs::writeBlock().

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Member Data Documentation

desiredRate

options::single<double> throttle::watch::desiredRate

private

Definition at line 19 of file throttle.h.

Referenced by update(), and wait().

i

options::single<double> throttle::watch::i

private

Definition at line 22 of file throttle.h.

Referenced by wait().

lastRate

double throttle::watch::lastRate

private

Definition at line 24 of file throttle.h.

Referenced by update(), and wait().

lastStop

clock_type::time_point throttle::watch::lastStop

private

Definition at line 25 of file throttle.h.

Referenced by update().

p

options::single<double> throttle::watch::p

private

Definition at line 21 of file throttle.h.

Referenced by wait().

rateIntegral

double throttle::watch::rateIntegral

private

Definition at line 23 of file throttle.h.

Referenced by update(), and wait().

tau

options::single<double> throttle::watch::tau

private

Definition at line 20 of file throttle.h.

Referenced by update().

updateMutex

std::mutex throttle::watch::updateMutex

private

Definition at line 26 of file throttle.h.

Referenced by update().

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

• src/throttle.h (v0.19-24-g0617ca1 with changes)