Lifetime churn based on shifted pareto distribution. More...

#include <ParetoChurn.h>

Inheritance diagram for ParetoChurn:

Classes
struct	node_stat

Public Member Functions
void	handleMessage (cMessage *msg)
void	initializeChurn ()
	ParetoChurn ()
	~ParetoChurn ()
Public Member Functions inherited from ChurnGenerator
virtual int	numInitStages () const
virtual void	initialize (int stage)
void	setNodeType (const NodeType &t)
const NodeType &	getNodeType ()

Protected Member Functions
void	updateDisplayString ()
void	createNode (double lifetime, double meanLifetime, double meanDeadtime, bool initialize)
void	deleteNode (TransportAddress &addr, double meanLifetime, double meanDeadtime)
double	shiftedPareto (double a, double b, int rng=0)
	implements a shifted pareto funcion
double	betaByMean (double mean, double alpha=3)
	returns a shifted pareto function's beta param by given mean and alpha
double	individualMeanTime (double mean)
	returns the individual mean life/dead time of a node
double	individualLifetime (double mean)
	returns a individual lifetime (or deadtime) based on a node's mean lifetime
double	residualLifetime (double mean)
	returns the resiidual lifetime (or deadtime) based on a node's mean lifetime
void	scheduleCreateNodeAt (double creationTime, double lifetime, double meanLifetime, double meanDeadtime)

Private Attributes
GlobalStatistics *	globalStatistics
double	initialMean
	mean of update interval during initalization phase
double	initialDeviation
	deviation of update interval during initalization phase
double	lifetimeMean
	mean node lifetime
double	deadtimeMean
	mean node deadtime
simtime_t	lastCreatetime
simtime_t	lastDeletetime
cMessage *	initFinishedTimer
	timer to signal end of init phase

Additional Inherited Members
Public Attributes inherited from ChurnGenerator
bool	init
	still in initialization phase?
int	terminalCount
	current number of overlay terminals
Protected Attributes inherited from ChurnGenerator
UnderlayConfigurator *	underlayConfigurator
int	targetOverlayTerminalNum
	final number of overlay terminals
NodeType	type
	the nodeType this generator is responsible for

Detailed Description

Lifetime churn based on shifted pareto distribution.

This class implements the curn model proposed in

Yao, Z.; Leonard, D.; Wang, X. & Loguinov, D. "Modeling Heterogeneous User Churn and Local Resilience of Unstructured P2P Networks" Proceedings of the 2006 14th IEEE International Conference on Network Protocols, 2006. ICNP '06. 2006, pp. 32–41

Definition at line 46 of file ParetoChurn.h.

Constructor & Destructor Documentation

ParetoChurn::ParetoChurn ( )

inline

Definition at line 51 of file ParetoChurn.h.

{ initFinishedTimer = NULL; };

ParetoChurn::~ParetoChurn ( )

Definition at line 247 of file ParetoChurn.cc.

                          {
    // destroy self timer messages
    cancelAndDelete(initFinishedTimer);
}

Member Function Documentation

double ParetoChurn::betaByMean	(	double	mean,
		double	alpha = `3`
	)

protected

returns a shifted pareto function's beta param by given mean and alpha

Parameters

mean	the wanted mean
alpha	the alph param of the shifted pareto (defaults to 3)

Returns: the beta parameter

Definition at line 209 of file ParetoChurn.cc.

Referenced by individualLifetime(), individualMeanTime(), and residualLifetime().

{
    return 1/(mean*(alpha -1));
}

void ParetoChurn::createNode	(	double	lifetime,
		double	meanLifetime,
		double	meanDeadtime,
		bool	initialize
	)

protected

Definition at line 162 of file ParetoChurn.cc.

Referenced by handleMessage().

{
    ParetoChurnMessage* churnMsg = new ParetoChurnMessage("DeleteNode");
    TransportAddress* ta = underlayConfigurator->createNode(type, initialize);
    churnMsg->setAddr(*ta);
    delete ta;
    churnMsg->setCreateNode(false);
    churnMsg->setMeanLifetime(meanLifetime);
    churnMsg->setMeanDeadtime(meanDeadtime);
    scheduleAt(std::max(simTime(), simTime() + lifetime
                   - underlayConfigurator->getGracefulLeaveDelay()), churnMsg);
    RECORD_STATS(globalStatistics->recordOutVector("ParetoChurn: Session Time",
                                                   lifetime));
    RECORD_STATS(globalStatistics->recordOutVector("ParetoChurn: "
                 "Time between creates", SIMTIME_DBL(simTime() - lastCreatetime)));
    lastCreatetime = simTime();
}

void ParetoChurn::deleteNode	(	TransportAddress &	addr,
		double	meanLifetime,
		double	meanDeadtime
	)

protected

Definition at line 184 of file ParetoChurn.cc.

Referenced by handleMessage().

{
    // Kill node
    underlayConfigurator->preKillNode(NodeType(), &addr);
    RECORD_STATS(globalStatistics->recordOutVector("ParetoChurn: "
               "Time between deletes", SIMTIME_DBL(simTime() - lastDeletetime)));
    lastDeletetime = simTime();
    scheduleCreateNodeAt(SIMTIME_DBL(simTime()+individualLifetime(meanDeadtime)),
                         individualLifetime(meanLifetime), meanLifetime,
                         meanDeadtime);
}

void ParetoChurn::handleMessage ( cMessage * msg )

virtual

Implements ChurnGenerator.

Definition at line 132 of file ParetoChurn.cc.

{
    if (!msg->isSelfMessage()) {
        delete msg;
        return;
    }
    // init phase finished
    if (msg ==  initFinishedTimer) {
        underlayConfigurator->initFinished();
        cancelEvent(initFinishedTimer);
        delete initFinishedTimer;
        initFinishedTimer = NULL;
        return;
    }
    ParetoChurnMessage* churnMsg = check_and_cast<ParetoChurnMessage*>(msg);
    if (churnMsg->getCreateNode() == true) {
        createNode(churnMsg->getLifetime(), churnMsg->getMeanLifetime(),
                   churnMsg->getMeanDeadtime(), false);
    } else {
        deleteNode(churnMsg->getAddr(), churnMsg->getMeanLifetime(),
                   churnMsg->getMeanDeadtime());
    }
    delete msg;
}

double ParetoChurn::individualLifetime ( double mean )

protected

returns a individual lifetime (or deadtime) based on a node's mean lifetime

Parameters

mean	the node's men lifetime

Returns: the lifetime

Definition at line 227 of file ParetoChurn.cc.

Referenced by deleteNode(), and initializeChurn().

{
    return shiftedPareto(3, betaByMean(mean));
}

double ParetoChurn::individualMeanTime ( double mean )

protected

returns the individual mean life/dead time of a node

Parameters

mean	the global mean life/dead time

Returns: the mean life/dead time of the node

Definition at line 221 of file ParetoChurn.cc.

Referenced by initializeChurn().

{
//    return shiftedPareto(3, betaByMean(mean*exp(1)));
    return shiftedPareto(3, betaByMean(mean));
}

void ParetoChurn::initializeChurn ( )

virtual

Implements ChurnGenerator.

Definition at line 44 of file ParetoChurn.cc.

{
    Enter_Method_Silent();
    initialMean = par("initPhaseCreationInterval");
    initialDeviation = initialMean / 3;
    lifetimeMean = par("lifetimeMean");
    deadtimeMean = par("deadtimeMean");
    WATCH(lifetimeMean);
    WATCH(deadtimeMean);
    lastCreatetime = 0;
    lastDeletetime = 0;
    globalStatistics = GlobalStatisticsAccess().get();
    double initFinishedTime = initialMean * targetOverlayTerminalNum;
    // try to create a stable equilibrium of nodes in init phase
    //
    // check for each node if he is present in initial state
    // and roll individual mean life+dead times
    int liveNodes = 0;
    double sum_l_i = 0;
    std::deque<node_stat> node_stats;
    for (int i = 0; liveNodes < (int)par("targetOverlayTerminalNum"); i++) {
        double nodeLifetimeMean = individualMeanTime(lifetimeMean);
        globalStatistics->recordOutVector("ParetoChurn: Node individual "
                                          "mean lifetime", nodeLifetimeMean);
        double nodeDeadtimeMean = individualMeanTime(deadtimeMean);
        globalStatistics->recordOutVector("ParetoChurn: Node individual "
                                          "mean deadtime", nodeDeadtimeMean);
        sum_l_i += 1.0/(nodeLifetimeMean + nodeDeadtimeMean);
        node_stat nodeStat;
        nodeStat.l = nodeLifetimeMean;
        nodeStat.d = nodeDeadtimeMean;
        double nodeAvailability = nodeLifetimeMean/(nodeLifetimeMean
                                                    + nodeDeadtimeMean);
        globalStatistics->recordOutVector("Node availability", nodeAvailability);
        nodeStat.alive = uniform(0, 1) < nodeAvailability;
        if (nodeStat.alive) {
            liveNodes++;
        }
        node_stats.push_back( nodeStat );
    }
    // compute "stretch" factor to reach the configured average lifetime
    // this is neccessary as "individual" lifetime mean has to be bigger than
    // "global" lifetime mean, as short-lived nodes will factor in more often
    double mean_life = 0;
    int numNodes = node_stats.size();
    for( int i = 0; i < numNodes; ++i ){
        node_stat& stat = node_stats[i];
        mean_life += stat.l/( (stat.l + stat.d) * sum_l_i );
    }
    double stretch = lifetimeMean/mean_life;
    liveNodes = 0;
    // schedule creation for all (alive or dead) nodes
    for( int i = 0; i < numNodes; ++i ){
        node_stat& stat = node_stats.front();
        stat.l *= stretch;
        stat.d *= stretch;
        if( stat.alive ){
            double scheduleTime = truncnormal(initialMean*liveNodes, initialDeviation);
            scheduleCreateNodeAt(scheduleTime, initFinishedTime - scheduleTime
                                 + residualLifetime(stat.l),
                                 stat.l, stat.d);
            liveNodes++;
        } else {
            scheduleCreateNodeAt(initFinishedTime
                                 + residualLifetime(stat.d),
                                 individualLifetime(stat.l),
                                 stat.l, stat.d);
        }
        node_stats.pop_front();
    }
    initFinishedTimer = new cMessage("initFinishTimer");
    scheduleAt(initFinishedTime, initFinishedTimer);
}

double ParetoChurn::residualLifetime ( double mean )

protected

returns the resiidual lifetime (or deadtime) based on a node's mean lifetime

Parameters

mean	the node's men lifetime

Returns: the residual lifetime

Definition at line 235 of file ParetoChurn.cc.

Referenced by initializeChurn().

{
    return shiftedPareto(2, betaByMean(mean));
}

void ParetoChurn::scheduleCreateNodeAt	(	double	creationTime,
		double	lifetime,
		double	meanLifetime,
		double	meanDeadtime
	)

protected

Definition at line 198 of file ParetoChurn.cc.

Referenced by deleteNode(), and initializeChurn().

{
    ParetoChurnMessage* churnMsg = new ParetoChurnMessage("CreateNode");
    churnMsg->setCreateNode(true);
    churnMsg->setLifetime(lifetime);
    churnMsg->setMeanLifetime(meanLifetime);
    churnMsg->setMeanDeadtime(meanDeadtime);
    scheduleAt(creationTime, churnMsg);
}

double ParetoChurn::shiftedPareto	(	double	a,
		double	b,
		int	rng = `0`
	)

protected

implements a shifted pareto funcion

Definition at line 214 of file ParetoChurn.cc.

Referenced by individualLifetime(), individualMeanTime(), and residualLifetime().

{
    // What OMNET calles "pareto_shifted" in reality is a gerneralized pareto,
    // not a shifted pareto...
    return (pareto_shifted(a, b, 0, rng)/b - 1) / b;
}

void ParetoChurn::updateDisplayString ( )

protectedvirtual

Implements ChurnGenerator.

Definition at line 240 of file ParetoChurn.cc.

{
    char buf[80];
    sprintf(buf, "pareto churn");
    getDisplayString().setTagArg("t", 0, buf);
}

Member Data Documentation

double ParetoChurn::deadtimeMean

private

mean node deadtime

Definition at line 107 of file ParetoChurn.h.

Referenced by initializeChurn().

GlobalStatistics* ParetoChurn::globalStatistics

private

Definition at line 102 of file ParetoChurn.h.

Referenced by createNode(), deleteNode(), and initializeChurn().

cMessage* ParetoChurn::initFinishedTimer

private

timer to signal end of init phase

Definition at line 112 of file ParetoChurn.h.

Referenced by handleMessage(), initializeChurn(), ParetoChurn(), and ~ParetoChurn().

double ParetoChurn::initialDeviation

private

deviation of update interval during initalization phase

Definition at line 105 of file ParetoChurn.h.

Referenced by initializeChurn().

double ParetoChurn::initialMean

private

mean of update interval during initalization phase

Definition at line 104 of file ParetoChurn.h.

Referenced by initializeChurn().

simtime_t ParetoChurn::lastCreatetime

private

Definition at line 109 of file ParetoChurn.h.

Referenced by createNode(), and initializeChurn().

simtime_t ParetoChurn::lastDeletetime

private

Definition at line 110 of file ParetoChurn.h.

Referenced by deleteNode(), and initializeChurn().

double ParetoChurn::lifetimeMean

private

mean node lifetime

Definition at line 106 of file ParetoChurn.h.

Referenced by initializeChurn().

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

Classes

Public Member Functions

Protected Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation