java多線程之並發工具類CountDownLatch,CyclicBarrier和Semaphore

public class CountDownLatchTest {
    private static class WorkThread extends Thread {
        private CountDownLatch cdl;
        public WorkThread(String name, CountDownLatch cdl) {
            super(name);
            this.cdl = cdl;
        }
        public void run() {
            System.out.println(this.getName() + "啟動瞭，時間為" + System.currentTimeMillis());
            System.out.println(this.getName() + "我要統計每個sheet的行數");
            try {
                cdl.await();
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(this.getName() + "執行完瞭，時間為" + System.currentTimeMillis());
        }
    }
    private static class sheetThread extends Thread {
        private CountDownLatch cdl;
        public sheetThread(String name, CountDownLatch cdl) {
            super(name);
            this.cdl = cdl;
        }
        public void run() {
            try {
                System.out.println(this.getName() + "啟動瞭，時間為" + System.currentTimeMillis());
                Thread.sleep(1000); //模擬任務執行耗時
                cdl.countDown();
                System.out.println(this.getName() + "執行完瞭，時間為" + System.currentTimeMillis() + " sheet的行數為：" + (int) (Math.random()*100));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    public static void main(String[] args) throws Exception {
        CountDownLatch cdl = new CountDownLatch(2);
        WorkThread wt0 = new WorkThread("WorkThread", cdl );
        wt0.start();
        sheetThread dt0 = new sheetThread("sheetThread1", cdl);
        sheetThread dt1 = new sheetThread("sheetThread2", cdl);
        dt0.start();
        dt1.start();
    }
}

public CountDownLatch(int count) {
        if (count < 0) throw new IllegalArgumentException("count < 0");
        this.sync = new Sync(count);
    }

/**
     * Synchronization control For CountDownLatch.
     * Uses AQS state to represent count.
     */
    private static final class Sync extends AbstractQueuedSynchronizer {
        private static final long serialVersionUID = 4982264981922014374L;
        Sync(int count) {
            setState(count);
        }
        int getCount() {
            return getState();
        }
        protected int tryAcquireShared(int acquires) {
            return (getState() == 0) ? 1 : -1;
        }
        protected boolean tryReleaseShared(int releases) {
            // Decrement count; signal when transition to zero
            for (;;) {
                int c = getState();
                if (c == 0)
                    return false;
                int nextc = c-1;
                if (compareAndSetState(c, nextc))
                    return nextc == 0;
            }
        }
    }

public void await() throws InterruptedException {
        sync.acquireSharedInterruptibly(1);
    }

public final void acquireSharedInterruptibly(int arg)
            throws InterruptedException {
        if (Thread.interrupted())
            throw new InterruptedException();
        if (tryAcquireShared(arg) < 0)
            doAcquireSharedInterruptibly(arg);
    }

/**
     * Acquires in shared interruptible mode.
     * @param arg the acquire argument
     */
    private void doAcquireSharedInterruptibly(int arg)
        throws InterruptedException {
        final Node node = addWaiter(Node.SHARED);
        boolean failed = true;
        try {
            for (;;) {
                final Node p = node.predecessor();
                if (p == head) {
                    int r = tryAcquireShared(arg);
                    if (r >= 0) {
                        setHeadAndPropagate(node, r);
                        p.next = null; // help GC
                        failed = false;
                        return;
                    }
                }
                if (shouldParkAfterFailedAcquire(p, node) &&
                    parkAndCheckInterrupt())
                    throw new InterruptedException();
            }
        } finally {
            if (failed)
                cancelAcquire(node);
        }
    }

public void countDown() {
        sync.releaseShared(1);
    }

public final boolean releaseShared(int arg) {
        if (tryReleaseShared(arg)) {
            doReleaseShared();
            return true;
        }
        return false;
    }

protected boolean tryReleaseShared(int releases) {
            // Decrement count; signal when transition to zero
            for (;;) {
                int c = getState();
                if (c == 0)
                    return false;
                int nextc = c-1;
                if (compareAndSetState(c, nextc))
                    return nextc == 0;
            }
        }

/**
     * Release action for shared mode -- signals successor and ensures
     * propagation. (Note: For exclusive mode, release just amounts
     * to calling unparkSuccessor of head if it needs signal.)
     */
    private void doReleaseShared() {
        /*
         * Ensure that a release propagates, even if there are other
         * in-progress acquires/releases.  This proceeds in the usual
         * way of trying to unparkSuccessor of head if it needs
         * signal. But if it does not, status is set to PROPAGATE to
         * ensure that upon release, propagation continues.
         * Additionally, we must loop in case a new node is added
         * while we are doing this. Also, unlike other uses of
         * unparkSuccessor, we need to know if CAS to reset status
         * fails, if so rechecking.
         */
        for (;;) {
            Node h = head;
            if (h != null && h != tail) {
                int ws = h.waitStatus;
                if (ws == Node.SIGNAL) {
                    if (!compareAndSetWaitStatus(h, Node.SIGNAL, 0))
                        continue;            // loop to recheck cases
                    unparkSuccessor(h);
                }
                else if (ws == 0 &&
                         !compareAndSetWaitStatus(h, 0, Node.PROPAGATE))
                    continue;                // loop on failed CAS
            }
            if (h == head)                   // loop if head changed
                break;
        }
    }

/**
     * Wakes up node's successor, if one exists.
     *
     * @param node the node
     */
    private void unparkSuccessor(Node node) {
        /*
         * If status is negative (i.e., possibly needing signal) try
         * to clear in anticipation of signalling.  It is OK if this
         * fails or if status is changed by waiting thread.
         */
        int ws = node.waitStatus;
        if (ws < 0)
            compareAndSetWaitStatus(node, ws, 0);
        /*
         * Thread to unpark is held in successor, which is normally
         * just the next node.  But if cancelled or apparently null,
         * traverse backwards from tail to find the actual
         * non-cancelled successor.
         */
        Node s = node.next;
        if (s == null || s.waitStatus > 0) {
            s = null;
            for (Node t = tail; t != null && t != node; t = t.prev)
                if (t.waitStatus <= 0)
                    s = t;
        }
        if (s != null)
            LockSupport.unpark(s.thread);
    }

public class SemaphoreTest {
    public static void main(String[] args) {
        final Semaphore semaphore = new Semaphore(5);
        Runnable runnable = () -> {
            try {
                semaphore.acquire();
                System.out.println(Thread.currentThread().getName() + "獲得瞭信號量>>>>>,時間為" + System.currentTimeMillis());
                Thread.sleep(1000);
          System.out.println(Thread.currentThread().getName() + "釋放瞭信號量<<<<<,時間為" + System.currentTimeMillis());
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                semaphore.release();
            }
        };
        Thread[] threads = new Thread[10];
        for (int i = 0; i < threads.length; i++)
            threads[i] = new Thread(runnable);
        for (int i = 0; i < threads.length; i++)
            threads[i].start();
    }
}

public Semaphore(int permits) {
        sync = new NonfairSync(permits);
    }

public Semaphore(int permits, boolean fair) {
        sync = fair ? new FairSync(permits) : new NonfairSync(permits);
    }

/**
     * Synchronization implementation for semaphore.  Uses AQS state
     * to represent permits. Subclassed into fair and nonfair
     * versions.
     */
    abstract static class Sync extends AbstractQueuedSynchronizer {
        private static final long serialVersionUID = 1192457210091910933L;
        Sync(int permits) {
            setState(permits);
        }
        final int getPermits() {
            return getState();
        }
        final int nonfairTryAcquireShared(int acquires) {
            for (;;) {
                int available = getState();
                int remaining = available - acquires;
                if (remaining < 0 ||
                    compareAndSetState(available, remaining))
                    return remaining;
            }
        }
        protected final boolean tryReleaseShared(int releases) {
            for (;;) {
                int current = getState();
                int next = current + releases;
                if (next < current) // overflow
                    throw new Error("Maximum permit count exceeded");
                if (compareAndSetState(current, next))
                    return true;
            }
        }
        final void reducePermits(int reductions) {
            for (;;) {
                int current = getState();
                int next = current - reductions;
                if (next > current) // underflow
                    throw new Error("Permit count underflow");
                if (compareAndSetState(current, next))
                    return;
            }
        }
        final int drainPermits() {
            for (;;) {
                int current = getState();
                if (current == 0 || compareAndSetState(current, 0))
                    return current;
            }
        }
    }

/**
     * Fair version
     */
    static final class FairSync extends Sync {
        private static final long serialVersionUID = 2014338818796000944L;
        FairSync(int permits) {
            super(permits);
        }
        protected int tryAcquireShared(int acquires) {
            for (;;) {
                if (hasQueuedPredecessors())
                    return -1;
                int available = getState();
                int remaining = available - acquires;
                if (remaining < 0 ||
                    compareAndSetState(available, remaining))
                    return remaining;
            }
        }
    }

public class CyclicBarrierTest extends Thread {
    private CyclicBarrier cb;
    private int sleepSecond;
    public CyclicBarrierTest(CyclicBarrier cb, int sleepSecond) {
        this.cb = cb;
        this.sleepSecond = sleepSecond;
    }
    public void run() {
        try {
            System.out.println(this.getName() + "開始, 時間為" + System.currentTimeMillis());
            Thread.sleep(sleepSecond * 1000);
            cb.await();
            System.out.println(this.getName() + "結束, 時間為" + System.currentTimeMillis());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            public void run() {
                System.out.println("CyclicBarrier的barrierAction開始運行, 時間為" + System.currentTimeMillis());
            }
        };
        CyclicBarrier cb = new CyclicBarrier(2, runnable);
        CyclicBarrierTest cbt0 = new CyclicBarrierTest(cb, 3);
        CyclicBarrierTest cbt1 = new CyclicBarrierTest(cb, 6);
        cbt0.start();
        cbt1.start();
    }
}

public CyclicBarrier(int parties, Runnable barrierAction) {
        if (parties <= 0) throw new IllegalArgumentException();
        this.parties = parties;
        this.count = parties;
        this.barrierCommand = barrierAction;
    }

/**
     * Main barrier code, covering the various policies.
     */
    private int dowait(boolean timed, long nanos)
        throws InterruptedException, BrokenBarrierException,
               TimeoutException {
        final ReentrantLock lock = this.lock;
        lock.lock();
        try {
            final Generation g = generation;
            if (g.broken)
                throw new BrokenBarrierException();
            if (Thread.interrupted()) {
                breakBarrier();
                throw new InterruptedException();
            }
            int index = --count;
            if (index == 0) {  // tripped
                boolean ranAction = false;
                try {
                    final Runnable command = barrierCommand;
                    if (command != null)
                        command.run();
                    ranAction = true;
                    nextGeneration();
                    return 0;
                } finally {
                    if (!ranAction)
                        breakBarrier();
                }
            }
            // loop until tripped, broken, interrupted, or timed out
            for (;;) {
                try {
                    if (!timed)
                        trip.await();
                    else if (nanos > 0L)
                        nanos = trip.awaitNanos(nanos);
                } catch (InterruptedException ie) {
                    if (g == generation && ! g.broken) {
                        breakBarrier();
                        throw ie;
                    } else {
                        // We're about to finish waiting even if we had not
                        // been interrupted, so this interrupt is deemed to
                        // "belong" to subsequent execution.
                        Thread.currentThread().interrupt();
                    }
                }
                if (g.broken)
                    throw new BrokenBarrierException();
                if (g != generation)
                    return index;
                if (timed && nanos <= 0L) {
                    breakBarrier();
                    throw new TimeoutException();
                }
            }
        } finally {
            lock.unlock();
        }
    }