Strategie
Class LRU

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

public class LRU

extends ReplaceStrategy

Implementation of the page replacement strategy LRU (Least-Recently-Used). The victim page is the page with the lowest time of last access.

Field Summary

static boolean	ISACCESSCOUNT Number of accesses is not relevant for this strategy.
static boolean	ISACCESSTIME Time of access is relevant for this strategy.
static boolean	ISINSERTIONTIME Time of insertion is not relevant for this strategy.
static java.lang.String	LONGNAME Long name of this streategy.
static int	MODBITCOUNT Number of reference-bits of this strategy.
static int	REFBITCOUNT Number of reference-bits of this strategy.
static java.lang.String	SHORTNAME Short name of this streategy.

Fields inherited from class Strategie.ReplaceStrategy

isAccessCount, isAccessTime, isInsertTime, isShowMemoryDetails, longName, modifyBitCount, referenceBitCount, shortName

Constructor Summary

LRU(boolean showDetails)
Creates a new instance of this strategy.

Method Summary

Memory	createMemory(int size, int refBits, int modBits) Creates a new instance of this strategy.
int	getDrawLfdNr(Memory memory, int i) Returns the index of the frame i in memory structure.
Page	getVictimPage(Memory memory, SimuData simu, GUI gui) Selects the next victim page.
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.

Methods inherited from class Strategie.ReplaceStrategy

getLongName, getModifyBitCount, getReferenceBitCount, getShortName, isAccessCount, isAccessTime, isInsertTime, isModifyBit, isReferenceBit, isShowMemoryDetails, setShowMemoryDetails, sortMemory

Methods inherited from class java.lang.Object

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

Field Detail

SHORTNAME

public static final java.lang.String SHORTNAME

Short name of this streategy.

LONGNAME

public static final java.lang.String LONGNAME

Long name of this streategy.

REFBITCOUNT

public static final int REFBITCOUNT

Number of reference-bits of this strategy.

MODBITCOUNT

public static final int MODBITCOUNT

Number of reference-bits of this strategy.

ISACCESSCOUNT

public static final boolean ISACCESSCOUNT

Number of accesses is not relevant for this strategy.

ISACCESSTIME

public static final boolean ISACCESSTIME

Time of access is relevant for this strategy.

ISINSERTIONTIME

public static final boolean ISINSERTIONTIME

Time of insertion is not relevant for this strategy.

Constructor Detail

LRU

public LRU(boolean showDetails)

Creates a new instance of this strategy.

Method Detail

createMemory

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

Creates a new instance of this strategy.

Overrides:

createMemory in class ReplaceStrategy

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.

Overrides:

setInitVictimPointer in class ReplaceStrategy

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.

Overrides:

getDrawLfdNr in class ReplaceStrategy

getVictimPage

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

Selects the next victim page. It's the oldest page in memory.

Overrides:

getVictimPage in class ReplaceStrategy

replacePage

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

Replaces the oldPage by the newPage in memory.

Overrides:

replacePage in class ReplaceStrategy

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.

Overrides:

reInsertPage in class ReplaceStrategy