A message sending rate control class for perfdhcp. More...

#include <rate_control.h>

Public Member Functions
	RateControl ()
	Default constructor. More...

	RateControl (const int rate, const int aggressivity)
	Constructor which sets desired rate and aggressivity. More...

int	getAggressivity () const
	Returns the value of aggressivity. More...

boost::posix_time::ptime	getDue () const
	Returns current due time to send next message. More...

uint64_t	getOutboundMessageCount ()
	Returns number of messages to be sent "now". More...

int	getRate () const
	Returns the rate. More...

bool	isLateSent () const
	Returns the value of the late send flag. More...

void	setAggressivity (const int aggressivity)
	Sets the value of aggressivity. More...

void	setRate (const int rate)
	Sets the new rate. More...

void	setRelativeDue (const int offset)
	Sets the value of the due time. More...

void	updateSendTime ()
	Sets the timestamp of the last sent message to current time. More...

Protected Member Functions
void	updateSendDue ()
	Calculates the send due. More...

Static Protected Member Functions
static boost::posix_time::ptime	currentTime ()
	Convenience function returning current time. More...

Protected Attributes
int	aggressivity_
	Holds an aggressivity value. More...

boost::posix_time::ptime	last_sent_
	Holds a timestamp when the last message was sent. More...

bool	late_sent_
	A flag which indicates that the calculated due time is in the past. More...

int	rate_
	Holds a desired rate value. More...

boost::posix_time::ptime	send_due_
	Holds a timestamp when the next message should be sent. More...

Detailed Description

A message sending rate control class for perfdhcp.

This class provides the means to control the rate at which messages of the specific type are sent by perfdhcp. Each message type, for which the desired rate can be specified, has a corresponding RateControl object. So, the perfdhcp is using up to three objects of this type at the same time, to control the rate of the following messages being sent:

Discover(DHCPv4) or Solicit (DHCPv6)
Renew (DHCPv6) or Request (DHCPv4) to renew leases.
Release

The purpose of the RateControl class is to track the due time for sending next message (or bunch of messages) to keep outbound rate of particular messages at the desired level. The due time is calculated using the desired rate value and the timestamp when the last message of the particular type has been sent. That puts the responsibility on the TestControl class to invoke the RateControl::updateSendDue, every time the message is sent.

The RateControl object returns the number of messages to be sent at the time. The number returned is 0, if perfdhcp shouldn't send any messages yet, or 1 (sometimes more) if the send due time has been reached.

Definition at line 38 of file rate_control.h.

Constructor & Destructor Documentation

◆ RateControl() [1/2]

isc::perfdhcp::RateControl::RateControl ( )

Default constructor.

Definition at line 17 of file rate_control.cc.

◆ RateControl() [2/2]

isc::perfdhcp::RateControl::RateControl	(	const int	rate,
		const int	aggressivity
	)

Constructor which sets desired rate and aggressivity.

Parameters

rate	A desired rate.
aggressivity	A desired aggressivity.

Definition at line 22 of file rate_control.cc.

References aggressivity_, isc_throw, and rate_.

Member Function Documentation

◆ currentTime()

boost::posix_time::ptime isc::perfdhcp::RateControl::currentTime ( )

staticprotected

Convenience function returning current time.

Returns: current time.

Definition at line 82 of file rate_control.cc.

Referenced by getOutboundMessageCount(), setRelativeDue(), updateSendDue(), and updateSendTime().

◆ getAggressivity()

int isc::perfdhcp::RateControl::getAggressivity ( ) const

inline

Returns the value of aggressivity.

Definition at line 51 of file rate_control.h.

References aggressivity_.

Referenced by getOutboundMessageCount().

◆ getDue()

boost::posix_time::ptime isc::perfdhcp::RateControl::getDue ( ) const

inline

Returns current due time to send next message.

Definition at line 56 of file rate_control.h.

References send_due_.

Referenced by isc::perfdhcp::TestControl::getCurrentTimeout().

◆ getOutboundMessageCount()

uint64_t isc::perfdhcp::RateControl::getOutboundMessageCount ( )

Returns number of messages to be sent "now".

This function calculates how many messages of the given type should be sent immediately when the call to the function returns, to catch up with the desired message rate.

The value returned depends on the due time calculated with the RateControl::updateSendDue function and the current time. If the due time has been hit, the non-zero number of messages is returned. If the due time hasn't been hit, the number returned is 0.

If the rate is non-zero, the number of messages to be sent is calculated as follows:

num = duration * rate

where duration is a time period between the due time to send next set of messages and current time. The duration is expressed in seconds with the fractional part having 6 or 9 digits (depending on the timer resolution). If the calculated value is equal to 0, it is rounded to 1, so as at least one message is sent.

The value of aggressivity limits the maximal number of messages to be sent one after another. If the number of messages calculated with the equation above exceeds the aggressivity, this function will return the value equal to aggressivity.

If the rate is not specified (equal to 0), the value calculated by this function is equal to aggressivity.

Returns: A number of messages to be sent immediately.

Definition at line 36 of file rate_control.cc.

References currentTime(), getAggressivity(), getRate(), send_due_, and updateSendDue().

Referenced by isc::perfdhcp::TestControl::run().

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◆ getRate()

int isc::perfdhcp::RateControl::getRate ( ) const

inline

Returns the rate.

Definition at line 94 of file rate_control.h.

References rate_.

Referenced by getOutboundMessageCount(), and updateSendDue().

◆ isLateSent()

bool isc::perfdhcp::RateControl::isLateSent ( ) const

inline

Returns the value of the late send flag.

The flag returned by this function indicates whether the new due time calculated by the RateControl::updateSendDue is in the past. This value is used by the TestControl object to increment the counter of the late sent messages in the StatsMgr.

Definition at line 104 of file rate_control.h.

References late_sent_.

Referenced by isc::perfdhcp::TestControl::checkLateMessages().

◆ setAggressivity()

void isc::perfdhcp::RateControl::setAggressivity ( const int aggressivity )

Sets the value of aggressivity.

Parameters

aggressivity A new value of aggressivity. This value must be a positive integer.

Exceptions

isc::BadValue if new value is not a positive integer.

Definition at line 123 of file rate_control.cc.

References aggressivity_, and isc_throw.

Referenced by isc::perfdhcp::TestControl::reset().

◆ setRate()

void isc::perfdhcp::RateControl::setRate ( const int rate )

Sets the new rate.

Parameters

rate	A new value of rate. This value must not be negative.

Exceptions

isc::BadValue if new rate is negative.

Definition at line 132 of file rate_control.cc.

References isc_throw, and rate_.

Referenced by isc::perfdhcp::TestControl::reset().

◆ setRelativeDue()

void isc::perfdhcp::RateControl::setRelativeDue ( const int offset )

Sets the value of the due time.

This function is intended for unit testing. It manipulates the value of the due time. The parameter passed to this function specifies the (positive or negative) number of seconds relative to current time.

Parameters

offset A number of seconds relative to current time which constitutes the new due time.

Definition at line 141 of file rate_control.cc.

References currentTime(), and send_due_.

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◆ updateSendDue()

void isc::perfdhcp::RateControl::updateSendDue ( )

protected

Calculates the send due.

This function calculates the send due timestamp using the current time and desired rate. The due timestamp is calculated as a sum of the timestamp when the last message was sent and the reciprocal of the rate in micro or nanoseconds (depending on the timer resolution). If the rate is not specified, the duration between two consecutive sends is one timer tick.

Definition at line 87 of file rate_control.cc.

References currentTime(), getRate(), isc_throw, last_sent_, late_sent_, and send_due_.

Referenced by getOutboundMessageCount().

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