public static void begin(int adults, int children, BoatGrader b) {
// Store the externally generated autograder in a class
// variable to be accessible by children.
bg = b;
// Instantiate global variables here.
numChildrenOnOahu = children; // all children start on Oahu
numAdultsOnOahu = adults; // all adults start on Oahu
numChildrenOnMolokai = 0;
numAdultsOnMolokai = 0;
pilotLock = new Lock(); // lock for traveling between islands
adultReadyAtOahu = new Condition2(pilotLock);
childReadyAtOahu = new Condition2(pilotLock);
childReadyAtMolokai = new Condition2(pilotLock);
gameEnd = new Lock(); // lock for whether or not to terminate
end = new Condition(gameEnd);
isDone = false;
communicator = new Communicator();
boatLocation = 0; // boat starts on Oahu
hasChildPilot = false; // starts with no ppl in boat
gameEnd.acquire();
// Logic for child threads to run.
Runnable childRunnable =
new Runnable() {
public void run() {
ChildItinerary();
}
};
// Logic for adult threads to run.
Runnable adultRunnable =
new Runnable() {
public void run() {
AdultItinerary();
}
};
// Create threads here. See section 3.4 of the Nachos for Java
// Walkthrough linked from the projects page.
for (int i = 0; i < children; i++) {
KThread child = new KThread(childRunnable);
child.setName("Child");
child.fork();
}
for (int i = 0; i < adults; i++) {
KThread adult = new KThread(adultRunnable);
adult.setName("Adult");
adult.fork();
}
while (!isDone) {
end.sleep();
// If we've moved all adults and children from Oahu, then we're done!
if (numChildrenOnOahu + numAdultsOnOahu == 0) {
System.out.println("Game over! Whoo!");
isDone = true;
break;
}
}
}
static void ChildItinerary() {
System.out.println("--- called child itinerary");
pilotLock.acquire();
Boolean readyToTerminate = false;
int currentLocation = 0; // current location set to Oahu
while (!isDone) {
if (currentLocation == 0) {
// If we are currently on Oahu...
while (boatLocation != 0 || numChildrenOnOahu == 1) {
System.out.println(
"--- child currently on Oahu, but the boat is not on Oahu ("
+ boatLocation
+ ") or we only have 1 child on Oahu ("
+ numChildrenOnOahu
+ ")");
// ...but the boat is not in Oahu or we only have 1 child on Oahu, then sleep.
childReadyAtOahu.sleep();
}
System.out.println("--- child currently on Oahu, ready to go");
if (numAdultsOnOahu == 0 && numChildrenOnOahu == 2) {
// ... we are ready to end the game!
System.out.println("--- ready to end the game");
readyToTerminate = true;
}
if (!hasChildPilot) {
hasChildPilot = true;
bg.ChildRowToMolokai();
printState();
currentLocation = 1; // this child are now now on Molokai
} else {
numChildrenOnOahu -= 2; // 2 kids will go Oahu --> Molokai, so decrement
bg.ChildRideToMolokai();
numChildrenOnMolokai += 2; // 2 kids have arrived on Molokai, so increment
printState();
currentLocation = 1; // this child are now now on Molokai
boatLocation = 1; // boat is now at Molokai
hasChildPilot = false;
if (readyToTerminate) {
gameEnd.acquire();
end.wake();
gameEnd.release();
childReadyAtMolokai.sleep();
} else {
System.out.println("--- child ready on Molokai");
childReadyAtMolokai.wake();
}
}
} else {
// Else, if we are currently on Molokai...
while (boatLocation != 1 || hasChildPilot) {
System.out.println(
"--- child currently on Molokai, but either the boat is not on Molokai or there's already a child pilot");
// ...but the boat is not at Molokai, then sleep.
childReadyAtMolokai.sleep();
}
// ...then send a child back to Oahu.
hasChildPilot = true;
System.out.println("--- child currently on Molokai, send one back to Oahu");
numChildrenOnMolokai--; // child is going from Molokai --> Oahu, so decrement
bg.ChildRowToOahu();
numChildrenOnOahu++; // child arrived at Oahu, so incrememt
printState();
boatLocation = 0; // boat is now at Oahu
currentLocation = 0; // child is now at Oahu
hasChildPilot = false;
if (numChildrenOnOahu >= 2) {
System.out.println("--- we now have 2 children on Oahu");
childReadyAtOahu.wake(); // let Oahu now we're ready to go
} else {
System.out.println("--- we don't enough children on Oahu so send an adult");
adultReadyAtOahu.wake();
childReadyAtOahu.sleep();
}
}
}
}