ns3::Synchronizer Class Reference

Base class used for synchronizing the simulation events to some real time "wall clock.". More...

#include <synchronizer.h>

Inheritance diagram for ns3::Synchronizer:

Collaboration diagram for ns3::Synchronizer:

List of all members.

Public Member Functions

bool Realtime (void)

Return true if this synchronizer is actually synchronizing to a realtime clock. The simulator sometimes needs to know this.

uint64_t GetCurrentRealtime (void)

Retrieve the value of the origin of the underlying normalized wall clock time in simulator timestep units.

void SetOrigin (uint64_t ts)

Establish a correspondence between a simulation time and the synchronizer real time.

uint64_t GetOrigin (void)

Retrieve the value of the origin of the simulation time in simulator timestep units.

int64_t GetDrift (uint64_t ts)

Retrieve the difference between the real time clock used to synchronize the simulation and the simulation time (in simulator timestep units).

bool Synchronize (uint64_t tsCurrent, uint64_t tsDelay)

Wait until the real time is in sync with the specified simulation time or until the synchronizer is Sigalled.

void Signal (void)

Tell a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time. This will cause the thread to wake and return to the simulator proper where it can get its bearings.

void SetCondition (bool)

Set the condition variable that tells a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time.

void EventStart (void)

Ask the synchronizer to remember what time it is. Typically used with EventEnd to determine the real execution time of a simulation event.

uint64_t EventEnd (void)

Ask the synchronizer to return the time step between the instant remembered during EventStart and now. Used in conjunction with EventStart to determine the real execution time of a simulation event.

Static Public Member Functions

static TypeId GetTypeId (void)

This method returns the TypeId associated to ns3::Object.

Protected Member Functions

virtual void DoSetOrigin (uint64_t ns)=0

Establish a correspondence between a simulation time and a wall-clock (real) time.

virtual bool DoRealtime (void)=0

Return true if this synchronizer is actually synchronizing to a realtime clock. The simulator sometimes needs to know this.

virtual uint64_t DoGetCurrentRealtime (void)=0

Retrieve the value of the origin of the underlying normalized wall clock time in simulator timestep units.

virtual bool DoSynchronize (uint64_t nsCurrent, uint64_t nsDelay)=0

Wait until the real time is in sync with the specified simulation time.

virtual void DoSignal (void)=0

Declaration of the method used to tell a posible simulator thread waiting in the DoSynchronize method that an event has happened which demands a reevaluation of the wait time.

virtual void DoSetCondition (bool)=0

Declaration of the method used to set the condition variable that tells a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time.

virtual int64_t DoGetDrift (uint64_t ns)=0

Declaration of method used to retrieve drift between the real time clock used to synchronize the simulation and the current simulation time.

Private Member Functions

uint64_t TimeStepToNanosecond (uint64_t ts)

Convert a simulator time step (which can be steps of time in a user-specified unit) to a normalized time step in nanosecond units.

uint64_t NanosecondToTimeStep (uint64_t ns)

Convert a normalized nanosecond count into a simulator time step (which can be steps of time in a user-specified unit).

Detailed Description

Base class used for synchronizing the simulation events to some real time "wall clock.".

The simulation clock is maintained as a 64-bit integer in a unit specified by the user through the TimeStepPrecision::Set function. This means that it is not possible to specify event expiration times with anything better than this user-specified accuracy. We use this clock for the simulation time.

The real-time clock is maintained as a 64-bit integer count of nanoseconds.

The synchronization between the simulation clock and the real-time clock is maintained using a combination of sleep-waiting, busy-waiting and a feedback loop.

Member Function Documentation

virtual void ns3::Synchronizer::DoSetCondition ( bool ) [protected, pure virtual]

Declaration of the method used to set the condition variable that tells a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time.

See also:: Synchronizer::SetCondition

Implemented in ns3::WallClockSynchronizer.

virtual void ns3::Synchronizer::DoSignal ( void ) [protected, pure virtual]

Declaration of the method used to tell a posible simulator thread waiting in the DoSynchronize method that an event has happened which demands a reevaluation of the wait time.

See also:: Synchronizer::Signal

Implemented in ns3::WallClockSynchronizer.

uint64_t ns3::Synchronizer::EventEnd ( void )

Ask the synchronizer to return the time step between the instant remembered during EventStart and now. Used in conjunction with EventStart to determine the real execution time of a simulation event.

See also:: Synchronizer::EventStart
TimeStepPrecision::Get

void ns3::Synchronizer::EventStart ( void )

Ask the synchronizer to remember what time it is. Typically used with EventEnd to determine the real execution time of a simulation event.

See also:: Synchronizer::EventEnd
TimeStepPrecision::Get

uint64_t ns3::Synchronizer::GetCurrentRealtime ( void )

Retrieve the value of the origin of the underlying normalized wall clock time in simulator timestep units.

Returns:: The normalized wall clock time (in simulator timestep units).

See also:: TimeStepPrecision::Get
Synchronizer::SetOrigin

int64_t ns3::Synchronizer::GetDrift ( uint64_t ts )

Retrieve the difference between the real time clock used to synchronize the simulation and the simulation time (in simulator timestep units).

Parameters:

ts

Simulation timestep from the simulator interpreted as current time in the simulator.

Returns:: Simulation timestep (in simulator timestep units) minus origin time (stored internally in nanosecond units).

See also:

TimeStepPrecision::Get

Synchronizer::SetOrigin

Synchronizer::DoGetDrift

uint64_t ns3::Synchronizer::GetOrigin ( void )

Retrieve the value of the origin of the simulation time in simulator timestep units.

Returns:: The simulation time used as the origin (in simulator timestep units).

See also:: TimeStepPrecision::Get
Synchronizer::SetOrigin

static TypeId ns3::Synchronizer::GetTypeId ( void ) [static]

This method returns the TypeId associated to ns3::Object.

No Attributes defined for this type.
No TraceSources defined for this type.

Reimplemented from ns3::Object.

bool ns3::Synchronizer::Realtime ( void )

Return true if this synchronizer is actually synchronizing to a realtime clock. The simulator sometimes needs to know this.

Returns:: True if locked with realtime, false if not.

void ns3::Synchronizer::SetCondition ( bool )

Set the condition variable that tells a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time.

See also:: Synchronizer::Signal

void ns3::Synchronizer::SetOrigin ( uint64_t ts )

Establish a correspondence between a simulation time and the synchronizer real time.

This method is expected to be called at the "instant" before simulation begins. At this point, simulation time = 0, and a set = 0 in this method. We then associate this time with the current value of the real time clock that will be used to actually perform the synchronization.

Subclasses are expected to implement the corresponding DoSetOrigin pure virtual method to do the actual real-time-clock-specific work of making the correspondence mentioned above.

Parameters:

ts

The simulation time we should use as the origin (in simulator timestep units).

See also:: TimeStepPrecision::Get
TimeStepPrecision::DoSetOrigin

void ns3::Synchronizer::Signal ( void )

Tell a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time. This will cause the thread to wake and return to the simulator proper where it can get its bearings.

See also:: Synchronizer::Synchronize
Synchronizer::DoSignal

bool ns3::Synchronizer::Synchronize	(	uint64_t	tsCurrent,
		uint64_t	tsDelay
	)

Wait until the real time is in sync with the specified simulation time or until the synchronizer is Sigalled.

This is where the real work of synchronization is done. The Time passed in as a parameter is the simulation time. The job of Synchronize is to translate from simulation time to synchronizer time (in a perfect world this is the same time) and then figure out how long in real-time it needs to wait until that synchronizer / simulation time comes around.

Subclasses are expected to implement the corresponding DoSynchronize pure virtual method to do the actual real-time-clock-specific work of waiting (either busy-waiting or sleeping, or some combination thereof) until the requested simulation time.

Parameters:

	tsCurrent	The current simulation time (in simulator timestep units).
	tsDelay	The simulation time we need to wait for (in simulator timestep units).

Returns:: True if the function ran to completion, false if it was interrupted by a Signal.

See also:

TimeStepPrecision::Get

Synchronizer::DoSynchronize

Synchronizer::Signal

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

src/simulator/synchronizer.h


Public Member Functions
bool	Realtime (void)
	Return true if this synchronizer is actually synchronizing to a realtime clock. The simulator sometimes needs to know this.
uint64_t	GetCurrentRealtime (void)
	Retrieve the value of the origin of the underlying normalized wall clock time in simulator timestep units.
void	SetOrigin (uint64_t ts)
	Establish a correspondence between a simulation time and the synchronizer real time.
uint64_t	GetOrigin (void)
	Retrieve the value of the origin of the simulation time in simulator timestep units.
int64_t	GetDrift (uint64_t ts)
	Retrieve the difference between the real time clock used to synchronize the simulation and the simulation time (in simulator timestep units).
bool	Synchronize (uint64_t tsCurrent, uint64_t tsDelay)
	Wait until the real time is in sync with the specified simulation time or until the synchronizer is Sigalled.
void	Signal (void)
	Tell a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time. This will cause the thread to wake and return to the simulator proper where it can get its bearings.
void	SetCondition (bool)
	Set the condition variable that tells a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time.
void	EventStart (void)
	Ask the synchronizer to remember what time it is. Typically used with EventEnd to determine the real execution time of a simulation event.
uint64_t	EventEnd (void)
	Ask the synchronizer to return the time step between the instant remembered during EventStart and now. Used in conjunction with EventStart to determine the real execution time of a simulation event.
Static Public Member Functions
static TypeId	GetTypeId (void)
	This method returns the TypeId associated to ns3::Object.
Protected Member Functions
virtual void	DoSetOrigin (uint64_t ns)=0
	Establish a correspondence between a simulation time and a wall-clock (real) time.
virtual bool	DoRealtime (void)=0
	Return true if this synchronizer is actually synchronizing to a realtime clock. The simulator sometimes needs to know this.
virtual uint64_t	DoGetCurrentRealtime (void)=0
	Retrieve the value of the origin of the underlying normalized wall clock time in simulator timestep units.
virtual bool	DoSynchronize (uint64_t nsCurrent, uint64_t nsDelay)=0
	Wait until the real time is in sync with the specified simulation time.
virtual void	DoSignal (void)=0
	Declaration of the method used to tell a posible simulator thread waiting in the DoSynchronize method that an event has happened which demands a reevaluation of the wait time.
virtual void	DoSetCondition (bool)=0
	Declaration of the method used to set the condition variable that tells a posible simulator thread waiting in the Synchronize method that an event has happened which demands a reevaluation of the wait time.
virtual int64_t	DoGetDrift (uint64_t ns)=0
	Declaration of method used to retrieve drift between the real time clock used to synchronize the simulation and the current simulation time.
Private Member Functions
uint64_t	TimeStepToNanosecond (uint64_t ts)
	Convert a simulator time step (which can be steps of time in a user-specified unit) to a normalized time step in nanosecond units.
uint64_t	NanosecondToTimeStep (uint64_t ns)
	Convert a normalized nanosecond count into a simulator time step (which can be steps of time in a user-specified unit).