我正在尝试使用监视器来实现自己的同步队列。通常，<我会使用已经实现的队列，但是我是线程技术的新手，我想看看幕后情况。我的逻辑将一个Linked-List包装在一个类中，沿着一个最大容量和一个当前容量，再加上一个标志，该标志指示另一端没有写程序（类似于C管道）。
工作方式：
似乎出了什么问题：每当我向队列中添加某些内容时，我也会打印添加的内容和当前容量。我发现容量超过了最大容量，而且由于所有方法都是同步的并且
现在，输入一些代码：
public class GiftQueue {
private final Queue<Gift> factoryGiftQueue;
private final int queueCapacity;
private volatile int currentCapacity;
private volatile boolean writingEndClosed;
public GiftQueue(Queue<Gift> factoryGiftQueue, int queueCapacity) {
this.factoryGiftQueue = factoryGiftQueue;
this.queueCapacity = queueCapacity;
this.currentCapacity = 0;
this.writingEndClosed = false;
}
public synchronized void push(Gift gift) {
while (currentCapacity == queueCapacity) {
try {
System.out.println("Queue full, awaiting pop...");
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
factoryGiftQueue.add(gift);
currentCapacity++;
System.out.println("Gift " + gift + " has been added to the queue. Queue size: " + currentCapacity);
notifyAll();
}
public synchronized Gift tryPop(int timeoutNanos) {
while (currentCapacity == 0) {
try {
System.out.println("Queue is empty, awaiting new push...");
wait();
if (currentCapacity == 0) {
System.out.println("Pop ABORTED");
return null;
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
Gift temp = factoryGiftQueue.poll();
--currentCapacity;
notifyAll();
try {
return temp;
} finally {
System.out.println("Gift has" + temp + " been pulled from queue. Queue size " + currentCapacity);
}
}
public synchronized void close() {
System.out.println("Writing end has been closed !");
writingEndClosed = true;
}
public synchronized boolean isAvailable() {
return (!(writingEndClosed) || currentCapacity != 0);
}
public synchronized boolean notEmpty() {
return currentCapacity != 0;
}
public synchronized boolean isFull() {
return currentCapacity == queueCapacity;
}
public synchronized boolean isEmpty() {
return currentCapacity == 0;
}
}
呼叫者对象是：
public class Reindeer implements Runnable {
private final int ID;
private final GiftQueue factoryQueue;
private final GiftQueue santaGiftQueue;
private final Semaphore serviceQueue;
public Reindeer(int ID, GiftQueue factoryQueue, GiftQueue santaGiftQueue,
Semaphore serviceQueue) {
this.ID = ID;
this.factoryQueue = factoryQueue;
this.santaGiftQueue = santaGiftQueue;
this.serviceQueue = serviceQueue;
}
@Override
public void run() {
while (factoryQueue.isAvailable()) {
Gift gift = null;
System.out.println("Reindeer " + ID + " working");
try {
serviceQueue.acquire();
if (factoryQueue.isEmpty()) {
serviceQueue.release();
continue;
}
gift = factoryQueue.tryPop(10);
} catch (InterruptedException e) {
e.printStackTrace();
}finally{
serviceQueue.release();
}
if (gift != null) {
santaGiftQueue.push(gift);
System.out.println("Reindeer " + ID + " sent a gift");
} else {
System.out.println("Reindeer " + ID + " will try again ");
awaitRandom();
}
}
System.out.println("Reindeer " + ID + " finished");
}
private void awaitRandom() {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
@Override
public String toString() {
return ID + "";
}
}
和
public class Factory implements Runnable {
private static final PositionBuilder positionBuilder = new PositionBuilder();
private final int maxGifts;
private final int factoryID;
private final int matrixSize;
private final int numberOfElves;
private final GiftQueue giftQueue;
private final Thread[] elvesThreads;
private final ArrayList<ElfRunnable> elves = new ArrayList<>();
private static final ElfBuilder elfBuilder = new ElfBuilder();
private final FactoryElfMap elfMap;
private final Semaphore reindeerSemaphore;
private final WorkshopStatus workshopStatus;
private final Semaphore serviceQueue;
private final Orchestrator orchestrator;
private int producedGifts;
public Factory(int factoryID, int numberOfToysTobeProduced, int matrixSize, int numberOfElves,
GiftQueue giftQueue, Orchestrator orchestrator,
FactoryElfMap elfMap,
Semaphore reindeerSemaphore,
WorkshopStatus workshopStatus,
Semaphore serviceQueue) {
this.factoryID = factoryID;
this.maxGifts = numberOfToysTobeProduced;
this.matrixSize = matrixSize;
this.numberOfElves = numberOfElves;
this.giftQueue = giftQueue;
this.orchestrator = orchestrator;
this.elfMap = elfMap;
this.reindeerSemaphore = reindeerSemaphore;
this.workshopStatus = workshopStatus;
this.serviceQueue = serviceQueue;
this.producedGifts = 0;
this.elvesThreads = new Thread[numberOfElves];
System.out.println(numberOfElves);
}
@Override
public void run() {
createElves();
startElves();
while (goalNotAchieved()) {
orchestrator.awaitSupervisorTurn();
System.out.println("Factory " + factoryID + " is working..");
queryPositions();
orchestrator.setWorkersTurn();
}
joinElves();
System.out.println("Factory " + factoryID + " FINISHED");
workshopStatus.signalDone();
giftQueue.close();
}
public synchronized boolean goalNotAchieved() {
return !(producedGifts == maxGifts);
}
private void joinElves() {
for (int i = 0; i < numberOfElves; i++) {
try {
elvesThreads[i].join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private void startElves() {
for (int i = 0; i < numberOfElves; i++) {
elvesThreads[i].start();
}
}
private void createElves() {
for (int i = 0; i < numberOfElves; i++) {
IPosition elfPosition = positionBuilder.create(matrixSize, elfMap);
ElfRunnable elfRunnable = elfBuilder.create(i, this, elfPosition,
orchestrator);
elfMap.addEntry(elfRunnable, elfPosition);
elfPosition.setOwner(elfRunnable);
elvesThreads[i] = new Thread(elfRunnable);
}
}
private synchronized void queryPositions() {
try {
reindeerSemaphore.acquire();
System.out.println("Factory " + factoryID + " starting query....");
for (ElfRunnable elf : elves) {
System.out.println(" Queried " + elf + ": (" + elf.getElfPosition() + ")");
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
reindeerSemaphore.release();
}
}
public synchronized void becomeAware(ElfRunnable elf) {
System.out.println("Factory " + factoryID + " got new elf");
elves.add(elf);
}
public synchronized void notifyGiftCreated(Gift gift) {
try {
reindeerSemaphore.acquire();
if (producedGifts == maxGifts) {
orchestrator.setWorkersTurn();
System.out.println("Rejecting " + gift);
} else {
serviceQueue.acquire();
producedGifts++;
if (giftQueue.isFull()) {
serviceQueue.release();
reindeerSemaphore.release();
notifyGiftCreated(gift);
return;
}
giftQueue.push(gift);
System.out.println("GIFTS: " + producedGifts);
serviceQueue.release();
}
} catch (InterruptedException e) {
e.printStackTrace();
}finally {
reindeerSemaphore.release();
}
}
@Override
public String toString() {
return factoryID + "";
}
}
示例输出：
Gift Gift-1329879510-34 has been added to the queue. Queue size: 1
GIFTS: 400
Reindeer 0 working
Gift hasGift-1329879510-34 been pulled from queue. Queue size 0
released
Gift Gift-1329879510-34 has been added to the queue. Queue size: 400 // <--- ???
Reindeer 1 sent a gift
Reindeer 1 working
released
Reindeer 0 working
Gift Gift-1015004123-1 has been added to the queue. Queue size: 1
GIFTS: 401
Gift hasGift-1015004123-1 been pulled from queue. Queue size 0
released
Queue full, awaiting pop...
released
Reindeer 0 working
Gift Gift--1853705096-37 has been added to the queue. Queue size: 1
GIFTS: 402
Gift hasGift--1853705096-37 been pulled from queue. Queue size 0
released
Queue full, awaiting pop...
Gift Gift-899203208-33 has been added to the queue. Queue size: 1
GIFTS: 403
Gift Gift--948848140-41 has been added to the queue. Queue size: 2
GIFTS: 404
Gift Gift--389884399-19 has been added to the queue. Queue size: 3
GIFTS: 405
Gift Gift-615746031-32 has been added to the queue. Queue size: 4
GIFTS: 406
Gift Gift-1784101203-3 has been added to the queue. Queue size: 5
GIFTS: 407
Gift Gift--1790412473-6 has been added to the queue. Queue size: 6
GIFTS: 408