Question

我的申请表中有GenericKeyedObjectPool。我可以使用close方法关闭它但是我应该如何等待客户端返回（并且池销毁）每个借用的对象到池中？

我需要像ExecutorService.awaitTermination这样的东西。

Answer 1

为GenericKeyedObjectPool创建一个包含所需awaitTermination方法的包装器。您可以检查close和returnObject调用，如果池已关闭且每个对象都已返回（=从此池中借用的当前实例总数为零），则会减少锁存器。

public final class ListenablePool<K, V> {

    private final GenericKeyedObjectPool<K, V> delegate;

    private final CountDownLatch closeLatch = new CountDownLatch(1);

    private final AtomicBoolean closed = new AtomicBoolean();

    public ListenablePool(final KeyedPoolableObjectFactory<K, V> factory) {
        this.delegate = new GenericKeyedObjectPool<K, V>(factory);
    }

    public V borrowObject(final K key) throws Exception {
        return delegate.borrowObject(key);
    }

    public void returnObject(final K key, final V obj) throws Exception {
        try {
            delegate.returnObject(key, obj);
        } finally {
            countDownIfRequired();
        }
    }

    private void countDownIfRequired() {
        if (closed.get() && delegate.getNumActive() == 0) {
            closeLatch.countDown();
        }
    }

    public void close() throws Exception {
        try {
            delegate.close();
        } finally {
            closed.set(true);
            countDownIfRequired();
        }
    }

    public void awaitTermination() throws InterruptedException {
        closeLatch.await();
    }

    public void awaitTermination(final long timeout, final TimeUnit unit) 
            throws InterruptedException {
        closeLatch.await(timeout, unit);
    }

    public int getNumActive() {
        return delegate.getNumActive();
    }

    // other delegate methods
}

Answer 2

关闭它应该是安全的，而不是等待返回所有对象。

来自GenericKeyedObjectPool.html#close()的文档：

关闭游泳池。池关闭后，borrowObject（）将失败使用IllegalStateException，但返回Object（Object）和 invalidateObject（Object）将继续使用返回的对象在返回时被摧毁。

如何安全地关闭GenericKeyedObjectPool？

2 个答案: