New Topic/Question
Reply
/**
* This program implements Bankers algorithm which will determine whether
* the state of the system that is read in from a file is safe or unsafe
* and output the result back to the user.
*
*/
import java.io.*;
import java.util.StringTokenizer;
import java.util.Scanner;
public class Banker
{
public static void main(String[]args)throws IOException
{
int n = 0; // Variable to hold the number of processes
int m = 0; // Variable to hold the number of resources
int count = 0; // Counter that holds the number of lines in the file
int lineCount = 0; // Counter that holds the number of lines in each matrix
int [] sumColumn; // Array holding the value of the sum of each column.
int [] sumRow; // Array holding the value of the sum of each row.
int [] resourceVector; // Array that holds the resource vector
int [] availableVector; // Array that holds the available vector
int [] work; // Array that holds the currently available vector
int [] processSequence; // Array holding the sequence of processes to run to completion
int index = 0; // Integer for holding the index value of the process sequence
boolean finish[]; // Boolean array that tells if a process has finished
int [][] claimMatrix; // Array that holds the claim matrix
int [][] allocationMatrix; // Array that holds the allocation matrix
int [][] needMatrix; // Array that holds the need matrix ( C-A );
boolean isSafe = false; // Boolean value that tells if the system is in a safe or unsafe state
// Variables to read in line from a file and tokenize
String line;
String fileIn;
StringTokenizer tokens;
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter in the name of the file : ");
fileIn = keyboard.nextLine();
// build input stream
FileReader fr = new FileReader(fileIn);
// Use Buffered reader to read one line at a time
BufferedReader bufRead = new BufferedReader(fr);
// Read first line
line = bufRead.readLine();
n = Integer.parseInt(line);
count++;
// Read second line
line = bufRead.readLine();
m = Integer.parseInt(line);
count++;
// Create each Matrix(n x m) and Vector( m )
claimMatrix = new int[n][m];
allocationMatrix = new int[n][m];
needMatrix = new int [n][m];
resourceVector = new int[m];
availableVector = new int[m];
work = new int[m];
finish = new boolean[n];
processSequence = new int[n];
sumColumn = new int[m];
sumRow = new int[n];
line = bufRead.readLine();
count++;
// Read through file and set Claim Matrix
while(line != null && lineCount < n)
{
tokens = new StringTokenizer(line);
if(tokens.hasMoreTokens())
{
for(int j = 0; j < m; j++)
{
claimMatrix[lineCount][j] = Integer.parseInt(tokens.nextToken());
}
}
line = bufRead.readLine();
lineCount++;
count++;
}
lineCount = 0;
// Read through file and set Allocation Matrix
while(line != null && lineCount < n)
{
tokens = new StringTokenizer(line);
if(tokens.hasMoreTokens())
{
for(int j = 0; j < m; j++)
{
allocationMatrix[lineCount][j] = Integer.parseInt(tokens.nextToken());
}
}
line = bufRead.readLine();
lineCount++;
count++;
}
// Read the last line and set Resource Vector
tokens = new StringTokenizer(line);
while(tokens.hasMoreTokens())
{
for(int i = 0; i < m; i++)
{
resourceVector[i] = Integer.parseInt(tokens.nextToken());
}
}
// Close the bufferreader and file
bufRead.close();
fr.close();
// Determine the initial need matrix
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
needMatrix[i][j] = claimMatrix[i][j] - allocationMatrix[i][j];
}
}
// Determine the initial available vector
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
sumColumn[j] += allocationMatrix[i][j];
sumRow[i] += needMatrix[i][j];
}
}
for(int j = 0; j < m; j++)
{
availableVector[j] = resourceVector[j] - sumColumn[j];
}
// Initialize Work and Finish
for(int j = 0; j < m; j++)
{
work[j]=availableVector[j];
}
for(int i = 0; i < n; i++)
{
finish[i] = false;
}
// Safety Algorithm (checks if the system is in a safe or unsafe state)
boolean found = false;
do
{
found = false; // Process found flag
int i = 0;
for(; i < n; i++)
{
if ((!finish[i]))
{
boolean good = true;
for (int j = 0; j < m; j++)
{
// If the need is greater than the available, then the process is not able to run to completion
// So it is not good
if(needMatrix[i][j] > work[j])
{
good = false;
break;
}
}
if (!good) continue; // Try another process
found = true;
break;
}
}
// Process is found that can run to completion, simulate execution
if(found)
{
finish[i] = true;
for (int j = 0; j < m; j++)
{
work[j] += allocationMatrix[i][j];
}
processSequence[index++] = i;
}
}while (found);
// Check if all processes have finished
for(int i = 0; i < n; i++)
{
if(!finish[i])
{
isSafe = false;
}
else
{
isSafe = true;
}
}
// Display output
System.out.println("Number of Processes : " + n);
System.out.println("Number of Resources : " + m + "\n");
System.out.println("Claim Matrix : ");
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
System.out.print(claimMatrix[i][j] + " ");
}
System.out.println();
}
System.out.println("\nAllocation Matrix : ");
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
System.out.print(allocationMatrix[i][j] + " ");
}
System.out.println();
}
System.out.println("\nResource Vector : ");
for(int i = 0; i < m; i++)
{
System.out.print(resourceVector[i] + " " );
}
System.out.println();
System.out.println("\nNeed Matrix : ");
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
System.out.print(needMatrix[i][j] + " ");
}
System.out.println();
}
System.out.println();
System.out.println("Initial Available Vector : ");
for(int j = 0; j < m; j++)
{
System.out.print(availableVector[j] + " ");
}
System.out.println("\n");
if(isSafe)
{
System.out.print("Process Sequence : ");
for(int i = 0; i < processSequence.length; i++)
{
System.out.print((processSequence[i]+1) + " ");
}
System.out.println();
System.out.println("This system is in a safe state!!!");
}
else
{
System.out.println("This system is not in a safe state!!!");
}
}
}
I also have attached two sample input files for a safe and unsafe state
line 1 : number of processes
line 2: number of resources
lines 3- 6 : claim matrix
lines 7-10 : allocation matrix
line 11 - resource vector
Safe Sample Input
-----------
4
3
3 2 2
6 1 3
3 1 4
4 2 2
1 0 0
6 1 3
2 1 1
0 0 2
9 3 6
-----------
Any feedback will be greatly appreciated.
Attached File(s)
-
Safe.txt (67bytes)
Number of downloads: 216 -
Unsafe.txt (57bytes)
Number of downloads: 163
MultiQuote
| 