Strategie
Class ReplaceStrategy

java.lang.Object
  |
  +--Strategie.ReplaceStrategy

Direct Known Subclasses:

Clock, FIFO, LFU, LIFO, LRU, Manual, MFU, MRU, NRU, OPT, RANDOM

public abstract class ReplaceStrategy

extends java.lang.Object

This class is an abstract class to work as a template for implementations of page replacement strategies. It contains detailed information about the implemented strategy like a short- and a long-name, switches to indicate whether some page-properties (time of access, time of insertion...) are important or not. These informations are needed to select the page that has to be replaced and are also needed by the drawing methods of the GUI to show only important informations.

Field Summary

private boolean	isAccessCount Is number of accesses relevant for this strategy?
private boolean	isAccessTime Is last time of accesses relevant for this strategy?
private boolean	isInsertTime Is time of insertion relevant for this strategy?
private boolean	isShowMemoryDetails Are memory details shown?
private java.lang.String	longName Long name of the strategy.
private int	modifyBitCount Number of modified-bits
private int	referenceBitCount Number of reference-bits
private java.lang.String	shortName Short name of the strategy.

Constructor Summary

ReplaceStrategy(java.lang.String sName, java.lang.String lName, int refBitCount, int modBitCount, boolean isAccessCount, boolean isAccessTime, boolean isInsertTime, boolean isShowMemoryDetails)
Creates a new instance of this strategy

Method Summary

Memory	createMemory(int size, int refBits, int modBits) Creates a new memory structure with the given size and number of reference- and modifyBits.
int	getDrawLfdNr(Memory memory, int i) Returns the index of the frame i in memory structure.
java.lang.String	getLongName() Returns the long name of this strategy.
int	getModifyBitCount() Returns the number of modifyBits needed by this strategy.
int	getReferenceBitCount() Returns the number of referenceBits needed by this strategy.
java.lang.String	getShortName() Returns the short name of this strategy.
Page	getVictimPage(Memory memory, SimuData simu, GUI gui) Selects the next victim page to the individual strategy criteria.
boolean	isAccessCount() Returns true, if the number of access to the pages is relevant for this strategy.
boolean	isAccessTime() Returns true, if the time of access to the pages is relevant for this strategy.
boolean	isInsertTime() Returns true, if the time of insertion to the pages is relevant for this strategy.
boolean	isModifyBit() Returns true, if the modify bit relevant for this strategy.
boolean	isReferenceBit() Returns true, if the reference bit relevant for this strategy.
boolean	isShowMemoryDetails() Returns true, if memory details should be shown.
void	reInsertPage(Memory memory, Page reInsertPage, SimuData simu, GUI gui) Reinserts a page into memory.
void	replacePage(Memory memory, Page oldPage, Page newPage, SimuData simu, GUI gui) Replaces the oldPage by the newPage in memory.
void	setInitVictimPointer(Memory memory) Sets the indexpointer to the page that has to be placed first.
void	setShowMemoryDetails(boolean isShowMemoryDetails) Sets the memory details to "show" or "hide".
void	sortMemory(Memory memory) Sorts the internal memory structure to the needs of the implemented strategy.

Methods inherited from class java.lang.Object

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

Field Detail

shortName

private java.lang.String shortName

Short name of the strategy.

longName

private java.lang.String longName

Long name of the strategy.

isAccessCount

private boolean isAccessCount

Is number of accesses relevant for this strategy?

isAccessTime

private boolean isAccessTime

Is last time of accesses relevant for this strategy?

isInsertTime

private boolean isInsertTime

Is time of insertion relevant for this strategy?

isShowMemoryDetails

private boolean isShowMemoryDetails

Are memory details shown?

referenceBitCount

private int referenceBitCount

Number of reference-bits

modifyBitCount

private int modifyBitCount

Number of modified-bits

Constructor Detail

ReplaceStrategy

public ReplaceStrategy(java.lang.String sName,
                       java.lang.String lName,
                       int refBitCount,
                       int modBitCount,
                       boolean isAccessCount,
                       boolean isAccessTime,
                       boolean isInsertTime,
                       boolean isShowMemoryDetails)

Creates a new instance of this strategy

Method Detail

createMemory

public Memory createMemory(int size,
                           int refBits,
                           int modBits)

Creates a new memory structure with the given size and number of reference- and modifyBits.

getShortName

public java.lang.String getShortName()

Returns the short name of this strategy.

getLongName

public java.lang.String getLongName()

Returns the long name of this strategy.

getReferenceBitCount

public int getReferenceBitCount()

Returns the number of referenceBits needed by this strategy.

getModifyBitCount

public int getModifyBitCount()

Returns the number of modifyBits needed by this strategy.

isAccessCount

public boolean isAccessCount()

Returns true, if the number of access to the pages is relevant for this strategy.

isAccessTime

public boolean isAccessTime()

Returns true, if the time of access to the pages is relevant for this strategy.

isInsertTime

public boolean isInsertTime()

Returns true, if the time of insertion to the pages is relevant for this strategy.

isModifyBit

public boolean isModifyBit()

Returns true, if the modify bit relevant for this strategy.

isReferenceBit

public boolean isReferenceBit()

Returns true, if the reference bit relevant for this strategy.

isShowMemoryDetails

public boolean isShowMemoryDetails()

Returns true, if memory details should be shown.

setShowMemoryDetails

public void setShowMemoryDetails(boolean isShowMemoryDetails)

Sets the memory details to "show" or "hide".

setInitVictimPointer

public void setInitVictimPointer(Memory memory)

Sets the indexpointer to the page that has to be placed first. Only needed at the beginning when creating new memory.

sortMemory

public void sortMemory(Memory memory)

Sorts the internal memory structure to the needs of the implemented strategy.

getDrawLfdNr

public int getDrawLfdNr(Memory memory,
                        int i)

Returns the index of the frame i in memory structure. The memory structure can have an strategy-dependant internal sort. This is needed for drawing the memory details in the strategy-dependant order.

getVictimPage

public Page getVictimPage(Memory memory,
                          SimuData simu,
                          GUI gui)

Selects the next victim page to the individual strategy criteria.

reInsertPage

public void reInsertPage(Memory memory,
                         Page reInsertPage,
                         SimuData simu,
                         GUI gui)

Reinserts a page into memory. Needed after a page hit. when the page's values has been changed and they are important for the sort in memory.

replacePage

public void replacePage(Memory memory,
                        Page oldPage,
                        Page newPage,
                        SimuData simu,
                        GUI gui)

Replaces the oldPage by the newPage in memory.