Maintain the event list. More...

#include "scheduler.h"

Inheritance diagram for ns3::Scheduler:

Collaboration diagram for ns3::Scheduler:

Classes
struct	Event
	Scheduler event. More...

struct	EventKey
	Structure for sorting and comparing Events. More...

Public Member Functions
	~Scheduler () override=0
	Destructor.

virtual void	Insert (const Event &ev)=0
	Insert a new Event in the schedule.

virtual bool	IsEmpty () const =0
	Test if the schedule is empty.

virtual Event	PeekNext () const =0
	Get a pointer to the next event.

virtual void	Remove (const Event &ev)=0
	Remove a specific event from the event list.

virtual Event	RemoveNext ()=0
	Remove the earliest event from the event list.

Public Member Functions inherited from ns3::Object
	Object ()
	Constructor.

	~Object () override
	Destructor.

void	AggregateObject (Ptr< Object > other)
	Aggregate two Objects together.

void	Dispose ()
	Dispose of this Object.

AggregateIterator	GetAggregateIterator () const
	Get an iterator to the Objects aggregated to this one.

TypeId	GetInstanceTypeId () const override
	Get the most derived TypeId for this Object.

template<typename T >
Ptr< T >	GetObject () const
	Get a pointer to the requested aggregated Object.

template<>
Ptr< Object >	GetObject () const
	Specialization of () for objects of type ns3::Object.

template<typename T >
Ptr< T >	GetObject (TypeId tid) const
	Get a pointer to the requested aggregated Object by TypeId.

template<>
Ptr< Object >	GetObject (TypeId tid) const
	Specialization of (TypeId tid) for objects of type ns3::Object.

void	Initialize ()
	Invoke DoInitialize on all Objects aggregated to this one.

bool	IsInitialized () const
	Check if the object has been initialized.

void	UnidirectionalAggregateObject (Ptr< Object > other)
	Aggregate an Object to another Object.

Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
	SimpleRefCount ()
	Default constructor.

	SimpleRefCount (const SimpleRefCount &o)
	Copy constructor.

uint32_t	GetReferenceCount () const
	Get the reference count of the object.

SimpleRefCount &	operator= (const SimpleRefCount &o)
	Assignment operator.

void	Ref () const
	Increment the reference count.

void	Unref () const
	Decrement the reference count.

Public Member Functions inherited from ns3::ObjectBase
virtual	~ObjectBase ()
	Virtual destructor.

void	GetAttribute (std::string name, AttributeValue &value, bool permissive=false) const
	Get the value of an attribute, raising fatal errors if unsuccessful.

bool	GetAttributeFailSafe (std::string name, AttributeValue &value) const
	Get the value of an attribute without raising errors.

void	SetAttribute (std::string name, const AttributeValue &value)
	Set a single attribute, raising fatal errors if unsuccessful.

bool	SetAttributeFailSafe (std::string name, const AttributeValue &value)
	Set a single attribute without raising errors.

bool	TraceConnect (std::string name, std::string context, const CallbackBase &cb)
	Connect a TraceSource to a Callback with a context.

bool	TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
	Connect a TraceSource to a Callback without a context.

bool	TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected with a context.

bool	TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected without a context.

Static Public Member Functions
static TypeId	GetTypeId ()
	Register this type.

Static Public Member Functions inherited from ns3::Object
static TypeId	GetTypeId ()
	Register this type.

Static Public Member Functions inherited from ns3::ObjectBase
static TypeId	GetTypeId ()
	Get the type ID.

Additional Inherited Members
Protected Member Functions inherited from ns3::Object
	Object (const Object &o)
	Copy an Object.

virtual void	DoDispose ()
	Destructor implementation.

virtual void	DoInitialize ()
	Initialize() implementation.

virtual void	NotifyNewAggregate ()
	Notify all Objects aggregated to this one of a new Object being aggregated.

Protected Member Functions inherited from ns3::ObjectBase
void	ConstructSelf (const AttributeConstructionList &attributes)
	Complete construction of ObjectBase; invoked by derived classes.

virtual void	NotifyConstructionCompleted ()
	Notifier called once the ObjectBase is fully constructed.

Related Symbols inherited from ns3::ObjectBase
static TypeId	GetObjectIid ()
	Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly.

Detailed Description

Maintain the event list.

In ns-3 the Scheduler manages the future event list. There are several different Scheduler implementations with different time and space tradeoffs. Which one is "best" depends in part on the characteristics of the model being executed. For optimized production work common practice is to benchmark each Scheduler on the model of interest. The utility program utils/bench-scheduler.cc can do simple benchmarking of each SchedulerImpl against an exponential or user-provided event time distribution.

The most important Scheduler functions for time performance are (usually) Scheduler::Insert (for new events) and Scheduler::RemoveNext (for pulling off the next event to execute). Simulator::Cancel is usually implemented by simply setting a bit on the Event, but leaving it in the Scheduler; the Simulator just skips those events as they are encountered.

For models which need a large event list the Scheduler overhead and per-event memory cost could also be important. Some models rely heavily on Scheduler::Cancel, however, and these might benefit from using Scheduler::Remove instead, to reduce the size of the event list, at the time cost of actually removing events from the list.

A summary of the main characteristics of each SchedulerImpl is provided below. See the individual Scheduler pages for details on the complexity of the other API calls. (Memory overheads assume pointers and std::size_t are both 8 bytes.)

Scheduler Type		Complexity
SchedulerImpl	Method	Time		Space
SchedulerImpl	Method	Insert()	RemoveNext()	Overhead	Per Event
CalendarScheduler	`<std::list> []`	Constant	Constant	24 bytes	16 bytes
HeapScheduler	Heap on `std::vector`	Logarithmic	Logarithmic	24 bytes	0
ListScheduler	`std::list`	Linear	Constant	24 bytes	16 bytes
MapScheduler	`std::map`	Logarithmic	Constant	40 bytes	32 bytes
PriorityQueueScheduler	`std::priority_queue<,std::vector>`	Logarithmic	Logarithmic	24 bytes	0

It is possible to change the Scheduler choice during a simulation, via Simulator::SetScheduler.

The Scheduler base class specifies the interface used to maintain the event list. If you want to provide a new event list scheduler, you need to create a subclass of this base class and implement all the pure virtual methods defined here.

The only tricky aspect of this API is the memory management of the EventImpl pointer which is a member of the Event data structure. The lifetime of this pointer is assumed to always be longer than the lifetime of the Scheduler class which means that the caller is responsible for ensuring that this invariant holds through calling EventId::Ref and SimpleRefCount::Unref at the right time. Typically, EventId::Ref is called before Insert and SimpleRefCount::Unref is called after a call to one of the Remove methods.

Definition at line 145 of file scheduler.h.

Constructor & Destructor Documentation

◆ ~Scheduler()

ns3::Scheduler::~Scheduler ( )

overridepure virtual

Destructor.

Definition at line 27 of file scheduler.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ GetTypeId()

TypeId ns3::Scheduler::GetTypeId ( )

static

Register this type.

Returns: The object TypeId.

Definition at line 33 of file scheduler.cc.

References ns3::TypeId::SetParent().

Here is the call graph for this function:

◆ Insert()

virtual void ns3::Scheduler::Insert ( const Event & ev )

pure virtual

Insert a new Event in the schedule.

Parameters

[in] ev Event to store in the event list

Implemented in ns3::CalendarScheduler, ns3::HeapScheduler, ns3::ListScheduler, ns3::MapScheduler, and ns3::PriorityQueueScheduler.

◆ IsEmpty()

virtual bool ns3::Scheduler::IsEmpty ( ) const

pure virtual

Test if the schedule is empty.

Returns: true if the event list is empty and false otherwise.

Implemented in ns3::CalendarScheduler, ns3::HeapScheduler, ns3::ListScheduler, ns3::MapScheduler, and ns3::PriorityQueueScheduler.

◆ PeekNext()

virtual Event ns3::Scheduler::PeekNext ( ) const

pure virtual

Get a pointer to the next event.

This method cannot be invoked if the list is empty.

Returns: A pointer to the next earliest event. The caller takes ownership of the returned pointer.

Implemented in ns3::CalendarScheduler, ns3::HeapScheduler, ns3::ListScheduler, ns3::MapScheduler, and ns3::PriorityQueueScheduler.

◆ Remove()

virtual void ns3::Scheduler::Remove ( const Event & ev )

pure virtual

Remove a specific event from the event list.

This method cannot be invoked if the list is empty.

Parameters

[in] ev The event to remove

Implemented in ns3::CalendarScheduler, ns3::HeapScheduler, ns3::ListScheduler, ns3::MapScheduler, and ns3::PriorityQueueScheduler.

◆ RemoveNext()

virtual Event ns3::Scheduler::RemoveNext ( )

pure virtual

Remove the earliest event from the event list.

This method cannot be invoked if the list is empty.

Returns: The Event.

Implemented in ns3::CalendarScheduler, ns3::HeapScheduler, ns3::ListScheduler, ns3::MapScheduler, and ns3::PriorityQueueScheduler.

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

src/core/model/scheduler.h
src/core/model/scheduler.cc

Classes

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ~Scheduler()

Member Function Documentation

◆ GetTypeId()

◆ Insert()

◆ IsEmpty()

◆ PeekNext()

◆ Remove()

◆ RemoveNext()