POTENTIAL DATA RACES AND SYNCHRONISATION ISSUES package medleySimulation;

import java.awt.Color;

import java.util.Random;

import java.util.concurrent.BlockingQueue;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.Semaphore;

public class Swimmer extends Thread $\{$

public static StadiumGrid stadium; $//$ shared

private FinishCounter finish; $//$ shared

private GridBlock currentBlock;

private Random rand;

private int movingSpeed;

private PeopleLocation myLocation;

private int ID; $//$ thread ID

private int team; $//$ team ID

private GridBlock start;

private CountDownLatch startLatch;

private Semaphore entranceSemaphore; $//$ Semaphore for controlling entrance access

private boolean isBackstroke; $//$ Flag to identify backstroke swimmers

private BlockingQueue backstrokeQueue; $//$ Queue for backstroke synchronization

private CountDownLatch backstrokeLatch; $//$ Latch to synchronize backstroke swimmers

public enum SwimStroke $\{$

Backstroke$(1,2\mathrm{.}5,$ Color.black$),$

Breaststroke$(2,2\mathrm{.}1,$ new Color$(255,102,0)),$

Butterfly$(3,2\mathrm{.}55,$ Color.magenta$),$

Freestyle$(4,2\mathrm{.}8,$ Color.red$)$;

private final double strokeTime;

private final int order; $//$ in minutes

private final Color colour;

SwimStroke$($int order, double sT$,$ Color c$)\{$

this.strokeTime $=$ sT;

this.order $=$ order;

this.colour $=$ c;

$\}$

public int getOrder$()\{$

return order;

$\}$

public Color getColour$()\{$

return colour;

$\}$

$\}$

private final SwimStroke swimStroke;

Swimmer$($int ID$,$ int t$,$ PeopleLocation loc, FinishCounter f$,$ int speed, SwimStroke s$,$ CountDownLatch startLatch, Semaphore entranceSemaphore, BlockingQueue backstrokeQueue, CountDownLatch backstrokeLatch$)\{$

this.swimStroke $=$ s;

this.ID $=$ ID;

this.movingSpeed $=$ speed;

this.myLocation $=$ loc;

this.team $=$ t;

this.start $=$ stadium.returnStartingBlock$($team$)$;

this.finish $=$ f;

this.rand $=$ new Random$()$;

this.startLatch $=$ startLatch;

this.entranceSemaphore $=$ entranceSemaphore;

this.isBackstroke $=($s $==$ SwimStroke.Backstroke$)$;

this.backstrokeQueue $=$ backstrokeQueue;

this.backstrokeLatch $=$ backstrokeLatch;

$\}$

public int getX$()\{$

return currentBlock.getX$()$;

$\}$

public int getY$()\{$

return currentBlock.getY$()$;

$\}$

public int getSpeed$()\{$

return movingSpeed;

$\}$

public SwimStroke getSwimStroke$()\{$

return swimStroke;

$\}$

public void enterStadium$()$ throws InterruptedException $\{$

System.out.println$("$Swimmer $"+$ ID $+"$ trying to enter the stadium."$)$;

entranceSemaphore.acquire$()$; $//$ Acquire semaphore to enter

try $\{$

currentBlock $=$ stadium.enterStadium$($myLocation$)$;

System.out.println$("$Swimmer $"+$ ID $+"$ has entered the stadium."$)$;

sleep$(200)$; $//$ Wait a bit at the door, look around

$\}$ finally $\{$

entranceSemaphore.release$()$; $//$ Release semaphore after entering

$\}$

$\}$

public void goToStartingBlocks$()$ throws InterruptedException $\{$

int x$\_$st $=$ start.getX$()$;

int y$\_$st $=$ start.getY$()$;

$//$ Move to the starting blocks

System.out.println$("$Swimmer $"+$ ID $+"$ moving to starting blocks at $("+$ x$\_$st $+","+$ y$\_$st $+").")$;

while $($currentBlock $!=$ start$)\{$

sleep$($movingSpeed $*3)$; $//$ Not rushing

currentBlock $=$ stadium.moveTowards$($currentBlock$,$ x$\_$st$,$ y$\_$st$,$ myLocation$)$;

$\}$

$//$ Wait until all backstroke swimmers are at their starting blocks

if $($isBackstroke$)\{$

System.out.println$("$Backstroke swimmer $"+$ ID $+"$ has reached the starting block."$)$;

backstrokeQueue.put$($this$)$; $//$ Add to queue

backstrokeLatch.countDown$()$; $//$ Decrement the latch

System.out.println$("$Backstroke swimmer $"+$ ID $+"$ added to queue. Countdown latch count: $"+$ backstrokeLatch.getCount$())$;

backstrokeLatch.await$()$; $//$ Wait for all backstroke swimmers to be ready

System.out.println$("$Backstroke swimmer $"+$ ID $+"$ is now ready."$)$;

$\}$ else $\{$

System.out.println$($swimStroke $+"$ swimmer $"+$ ID $+"$ waiting for backstroke swimmers."$)$;

backstrokeLatch.await$()$; $//$ Ensure non$-$backstroke swimmers wait for backstroke swimmers

System.out.println$($swimStroke $+"$ swimmer $"+$ ID $+"$ is now ready."$)$;

$\}$

$\}$

private void dive$()$ throws InterruptedException $\{$

int x $=$ currentBlock.getX$()$;

int y $=$ currentBlock.getY$()$;

System.out.println$("$Swimmer $"+$ ID $+"$ diving from $("+$ x $+","+$ y $+").")$;

currentBlock $=$ stadium.jumpTo$($currentBlock$,$ x$,$ y $-2,$ myLocation$)$;

$\}$

private void swimRace$()$ throws Interrupte