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//Java Program to implement 2 phase locking protocol.
TwoPhaseLocking.java
package twopahselocking;
public class TwoPahseLocking {
public static void main(String[] args) throws InterruptedException {
System.out.println("+++++2 Phase Locking Protocol+++++");
Thread t1 = new Thread(new Runner());
Thread t2 = new Thread(new Runner());
Thread t3 = new Thread(new Runner());
t1.setName("Transaction-1");
t2.setName("Transaction-2");
t3.setName("Transaction-3");
System.out.println("Starting the Transactions~!~!~!");
t1.start();
t2.start();
t3.start();
t1.join();
t2.join();
t3.join();
Thread.sleep(20000);
System.out.println("All transactions are executed successfully!!!");
}
}
Runner.java
package twopahselocking;
import static java.lang.Thread.sleep;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Runner implements Runnable {
public static int dbloc=0;
public static String str,str1;
public void run() {
test();
}
public synchronized void test()
{
str = Thread.currentThread().getName();
if(str.equals(Thread.currentThread().getName()) && dbloc==0)
{
str1=Thread.currentThread().getName();
System.out.println("\n"+str1+" is started!!!");
dbloc=1;
System.out.println(str1+ " is acquired lock");
TransactionPerform obj = new TransactionPerform();
System.out.println(str1+" is going to perform its transaction");
obj.perfTrans();
try {
sleep(5000);
} catch (InterruptedException ex) {
Logger.getLogger(Runner.class.getName()).log(Level.SEVERE, null, ex);
}
dbloc=0;
System.out.println(str1+" is completed its execution!!!");
System.out.println("Notifying other transaction to start again");
}
else
{
System.out.println(str+" is waiting for its turn.");
try {
sleep(2000);
test();
} catch (InterruptedException ex) {
Logger.getLogger(Runner.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}
TransactionPerform.java
package twopahselocking;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class TransactionPerform {
public static int querryNum=1;
String str;
public static String querry1 = "Insert into Staff values('S128','Kusum
Gupta','Mumbai','F','1992-02-13','8108146033','Nursary course','Nurse')";
public static String querry2 = "Update Staff Set Name='Mungesh Babulal' where
Staff_ID='S114'";
public static String querry3 = "Update Staff Set Contact_no='8108146033' where
Staff_ID='S117'";
int numRowsChanged;
public synchronized void perfTrans()
{
try {
//Create statement
//Get Connection
Connection myCon =
DriverManager.getConnection("jdbc:mysql://localhost:3306/HMS", "root", "");
//Create statement
System.out.println("\nDatabase connection is created");
Statement myStm = myCon.createStatement();
//Execute querry
//ResultSet myRs = myStm.executeUpdate(q);
if(querryNum==1)
numRowsChanged = myStm.executeUpdate(querry1);
else if(querryNum==2)
numRowsChanged = myStm.executeUpdate(querry2);
else if(querryNum==3)
numRowsChanged = myStm.executeUpdate(querry3);
querryNum++;
//Process result
if (numRowsChanged >= 1) {
System.out.println("Table Staff Updated Successfully!!!");
} else {
System.out.println("Table Staff does not Updated Successfully!!!");
}
}
catch (Exception e) {
}
}
}
Output:-
run:
+++++2 Phase Locking Protocol+++++
Starting the Transactions~!~!~!
Transaction-1 is started!!!
Transaction-1 is acquired lock
Transaction-2 is waiting for its turn.
Transaction-1 is going to perform its transaction
Transaction-3 is waiting for its turn.
Database connection is created
Table Staff Updated Successfully!!!
Transaction-2 is waiting for its turn.
Transaction-3 is waiting for its turn.
Transaction-2 is waiting for its turn.
Transaction-3 is waiting for its turn.
Transaction-1 is completed its execution!!!
Notifying other transaction to start again
Transaction-2 is started!!!
Transaction-2 is acquired lock
Transaction-2 is going to perform its transaction
Transaction-3 is waiting for its turn.
Database connection is created
Table Staff Updated Successfully!!!
Transaction-3 is waiting for its turn.
Transaction-3 is waiting for its turn.
Transaction-2 is completed its execution!!!
Notifying other transaction to start again
Transaction-3 is started!!!
Transaction-3 is acquired lock
Transaction-3 is going to perform its transaction
Database connection is created
Table Staff Updated Successfully!!!
Transaction-3 is completed its execution!!!
Notifying other transaction to start again
All transactions are executed successfully!!!
BUILD SUCCESSFUL (total time: 37 seconds)