gridsim.net
Class FIFOScheduler

Object
  FIFOScheduler

All Implemented Interfaces:

PacketScheduler

public class FIFOScheduler
extends Object
implements PacketScheduler

FIFOScheduler implements a First in First Out Scheduler. This means that all the packets are enqued at the tail of a queue, and packets depart from the head of the queue. Packets are not reordered, and no differentiated service will be provided.

Since:

GridSim Toolkit 3.1

Author:

Gokul Poduval & Chen-Khong Tham, National University of Singapore

Invariant:

$none

Constructor Summary

FIFOScheduler()
Creates a new packet scheduler with the name "FIFOScheduler".

FIFOScheduler(double baudRate)
Creates a new FIFO packet scheduler with the specified baud rate (in bits/s).

FIFOScheduler(String name)
Creates a new FIFO packet scheduler with the specified name.

FIFOScheduler(String name, double baudRate)
Creates a new FIFO packet scheduler with the specified name and baud rate (in bits/s).

Method Summary

Packet	deque() In this scheduler, the packet returned is always from the head of the queue.
boolean	enque(Packet np) In this scheduler, the packet is put into the tail of the queue.
double	getBaudRate() Returns the baud rate of the egress port that is using this scheduler.
int	getRouterID() Gets the router ID that hosts this scheduler.
int	getSchedID() Gets the ID of this scheduler.
String	getSchedName() Gets the name of this scheduler.
boolean	isEmpty() Determines whether the scheduler is currently keeping any packets in its queue(s).
boolean	setBaudRate(double rate) Sets the baud rate that this scheduler will be sending packets at.
boolean	setRouterID(int routerID) Sets the router ID that hosts this scheduler.
int	size() Determines the number of packets that are currently enqueued in this scheduler.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FIFOScheduler

public FIFOScheduler(String name,
                     double baudRate)
              throws ParameterException

Creates a new FIFO packet scheduler with the specified name and baud rate (in bits/s). The name can be useful for debugging purposes, but serves no functional purpose.

Parameters:

name - Name of this scheduler

baudRate - baud rate in bits/s of the port that is using this scheduler.

Throws:

ParameterException - This happens when the name is null or the baud rate <= 0

Pre Condition:

name != null, baudRate > 0

Post Condition:

$none

FIFOScheduler

public FIFOScheduler(double baudRate)
              throws ParameterException

Creates a new FIFO packet scheduler with the specified baud rate (in bits/s). The name is set to a generic name: "FIFOScheduler".

Parameters:

baudRate - baud rate in bits/s of the port that is using this scheduler.

Throws:

ParameterException - This happens when the baud rate <= 0

Pre Condition:

baudRate > 0

Post Condition:

$none

FIFOScheduler

public FIFOScheduler(String name)
              throws ParameterException

Creates a new FIFO packet scheduler with the specified name. The baud rate is left at 0, and should be set with PacketScheduler.setBaudRate(double) before the simulation starts.

Parameters:

name - Name of this scheduler

Throws:

ParameterException - This happens when the name is null

See Also:

PacketScheduler.setBaudRate(double)

Pre Condition:

name != null

Post Condition:

$none

FIFOScheduler

public FIFOScheduler()
              throws ParameterException

Creates a new packet scheduler with the name "FIFOScheduler". The baud rate is left at 0, and should be set with PacketScheduler.setBaudRate(double) before the simulation starts.

Throws:

ParameterException - This happens when the name is null

See Also:

PacketScheduler.setBaudRate(double)

Pre Condition:

$none

Post Condition:

$none

Method Detail

enque

public boolean enque(Packet np)

In this scheduler, the packet is put into the tail of the queue. There is no buffer management, so packets are never dropped, and the queue can grow as long as system memory is available.

Specified by:

enque in interface PacketScheduler

Parameters:

np - A Packet to be enqued by this scheduler.

Returns:

true if enqued, false otherwise

Pre Condition:

np != null

Post Condition:

$none

deque

public Packet deque()

In this scheduler, the packet returned is always from the head of the queue.

Specified by:

deque in interface PacketScheduler

Returns:

the packet to be sent out, or null if a list is empty

Pre Condition:

$none

Post Condition:

$none

isEmpty

public boolean isEmpty()

Determines whether the scheduler is currently keeping any packets in its queue(s).

Specified by:

isEmpty in interface PacketScheduler

Returns:

true if no packets are enqueued, false otherwise

Pre Condition:

$none

Post Condition:

$none

size

public int size()

Determines the number of packets that are currently enqueued in this scheduler.

Specified by:

size in interface PacketScheduler

Returns:

the number of packets enqueud by this scheduler.

Pre Condition:

$none

Post Condition:

$none

getSchedID

public int getSchedID()

Gets the ID of this scheduler.

Specified by:

getSchedID in interface PacketScheduler

Returns:

the ID of this scheduler or -1 if no ID is found

Pre Condition:

$none

Post Condition:

$none

getSchedName

public String getSchedName()

Gets the name of this scheduler.

Specified by:

getSchedName in interface PacketScheduler

Returns:

the name of this scheduler

Pre Condition:

$none

Post Condition:

$none

setBaudRate

public boolean setBaudRate(double rate)

Sets the baud rate that this scheduler will be sending packets at.

Specified by:

setBaudRate in interface PacketScheduler

Parameters:

rate - the baud rate of this scheduler (in bits/s)

Pre Condition:

rate > 0

Post Condition:

$none

getBaudRate

public double getBaudRate()

Returns the baud rate of the egress port that is using this scheduler. If the baud rate is zero, it means you haven't set it up.

Specified by:

getBaudRate in interface PacketScheduler

Returns:

the baud rate in bits/s

See Also:

PacketScheduler.setBaudRate(double)

Pre Condition:

$none

Post Condition:

$result >= 0

setRouterID

public boolean setRouterID(int routerID)

Sets the router ID that hosts this scheduler.

Specified by:

setRouterID in interface PacketScheduler

Parameters:

routerID - the router ID that hosts this scheduler

Returns:

true if successful or false otherwise

Pre Condition:

$none

Post Condition:

$none

getRouterID

public int getRouterID()

Gets the router ID that hosts this scheduler.

Specified by:

getRouterID in interface PacketScheduler

Returns:

the router ID or -1 if no ID is found

Pre Condition:

$none

Post Condition:

$none