Question

Using Jeliot, execute the following algorithm which implements a buffer pool algorithm. The algorithm offers options for three different heuristics including LRU, LFU, and FIFO.

Answer 1

code:

import Prog1Tools.IOTools;
import java.util.*;

class replacepage
{
public static void main(String args[]) {

boolean flag;
int f, page=0, ch, pgf=0, n, chn=0, k, pt;
int pages[];

//pgf-page fault

System.out.println("Menu 1.FIFO 2. LRU 3. LFU");
System.out.println("ENTER YOUR CHOICE: ");

Scanner in = new Scanner(System.in);
ch = in.nextInt();
switch(ch)
{
case 1:
pt=0;
System.out.println("enter no. of buffers (available buffers in the pool): ");
f=in.nextInt();
int buffer[]=new int[f];
for(int i=0;i<f;i++)
{
buffer[i]=-1;
}
System.out.println("enter the no of pages (items to be stored): ");
n=in.nextInt();
pages=new int[n];
System.out.println("enter the page value (an item to place in a buffer): ");
for(int j=0;j<n;j++)
pages[j]=in.nextInt();
do{
int pg=0;
for(pg=0;pg<n;pg++)
{
page=pages[pg];
flag=true;
for(int j=0;j<f;j++)
{
if(page==buffer[j])
{
flag=false;
break;
}
}
if(flag)
{
buffer[pt]=page;
pt++;
if(pt==f) pt=0;
System.out.print("buffer :");
for(int j=0;j<f;j++)
System.out.print(buffer[j]+" ");
System.out.println();
pgf++;
}
else
{
System.out.print("buffer :");
for(int j=0;j<f;j++)
System.out.print(buffer[j]+" ");
System.out.println();
}
chn++;
}
} while(chn!=n);
break;
case 2:
k=0;
System.out.println("enter no. of buffers (available buffers in the pool): ");
f=in.nextInt();
int buffer1[]=new int[f];
int a[]=new int[f];
int b[]=new int[f];
for(int i=0;i<f;i++)
{
buffer1[i]=-1;
a[i]=-1;
b[i]=-1;
}
System.out.println("enter the no of pages (items to be stored): ");
n=in.nextInt();
pages=new int[n];
System.out.println("enter the page value (an item to place in a buffer): ");
for(int j=0;j<n;j++)
pages[j]=in.nextInt();
do{
int pg=0;
for(pg=0;pg<n;pg++)
{
page=pages[pg];
flag=true;
for(int j=0;j<f;j++)
{
if(page==buffer1[j])
{
flag=false; break;
}
}

for(int j=0;j<f && flag;j++)
{
if(buffer1[j]==a[f-1])
{
k=j;
break;
}
}

if(flag)
{
buffer1[k]=page;
System.out.println("buffer :" );
for(int j=0;j<f;j++)
System.out.print(buffer1[j]+" ");
pgf++;
System.out.println();
}
else
{
System.out.println("buffer :" );
for(int j=0;j<f;j++)
System.out.print(buffer1[j]+" ");
System.out.println();
}
int p=1;
b[0]=page;
for(int j=0;j<a.length;j++)
{
if(page!=a[j] && p<f)
{
b[p]=a[j];
p++;
}
}
for(int j=0;j<f;j++)
{
a[j]=b[j];
}
chn++;
}
} while(chn!=n);
break;

case 3:
k=0;
pgf=0;
int sml;
System.out.println("enter no. of buffers (available buffers in the pool): ");
f=in.nextInt();
int buffer2[]=new int[f];
int cnt[]=new int [f];
flag=true;
for(int i=0;i<f;i++)
{
buffer2[i]=-1;
cnt[i]=0;
}
System.out.println("enter the page value (an item to place in a buffer): ");
n=in.nextInt();
pages=new int[n];
System.out.println("enter the page value (an item to place in a buffer): ");
for(int j=0;j<n;j++)
pages[j]=in.nextInt();
do
{
int pg=0;
for(pg=0;pg<n;pg++)
{
page=pages[pg];
flag=true;
for(int j=0;j<f;j++)
{
if(page==buffer2[j])
{
flag=false;
cnt[j]++;
break;
}
}
if(flag)
{
sml=cnt[0];
for(int j=0;j<f;j++)
{
if(cnt[j]<sml)
{
sml=cnt[j];
break;
}
}
for(int j=0;j<f;j++)
{
if(sml==cnt[j] )
{
buffer2[j]=page;
k=j;
break;
}
}
cnt[k]=1;
System.out.print("buffer :");
for(int j=0;j<f;j++)
{
System.out.print(buffer2[j]+" ");
System.out.println();
pgf++;
}
}
else
{
System.out.print("buffer :");
for(int j=0;j<f;j++)
System.out.print(buffer2[j]+" ");
System.out.println();
}
chn++;
}
} while(chn!=n);
break;
}
}
}
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