如何从 Semaphore 获取获取的索引

Question

我有一个大小为 4 的 int 数组，一次只有一个线程可以访问一个数组单元。 我考虑过使用信号量，但我不知道如何或是否有办法获取获取的索引 我构建了一个代码示例来解释黄油：

public class Temp {

    private ExecutorService executeService;
    private Semaphore semaphore;
    private int[] syncArray; // only one thread can access an array cell at the same time

    public Temp() {
        syncArray = new int[]{1,2,3,4};
        executeService = Executors.newFixedThreadPool(10);
        semaphore = new Semaphore(syncArray.length, true);

        for(int i = 0;i < 100; i++) {
            executeService.submit(new Runnable() {
                @Override
                public void run() {
                    semaphore.acquire();

                    // here I want to access one of the array cell
                    // dose not matter witch one as long as no other thread is currently use it
                    int syncArrayIndex = semaphore.getAcquiredIndex(); // is something like this possible?
                    syncArray[syncArrayIndex] += ...;

                    semaphore.release();
                }
            });
        }

    }
}

编辑： 这是一段看起来更接近我真正问题的代码：

public class Temp {

    private ExecutorService executeService;
    private Semaphore semaphore;
    private static ChromeDriver driver;

    public Temp() {
        executeService = Executors.newFixedThreadPool(10);
    }

    public Future<WikiPage> getWikiPage(String url) {
        executeService.submit(new PageRequest(url) {

        });
    }

    private static class PageRequest implements Callable<WikiPage> {
        String url;
        public PageRequest(String url) {
            this.url = url;
        }
        @Override
        public WikiPage call() throws Exception {
            String html = "";
            synchronized (driver) {
                html = ...// get the wiki page, this part takes a log time
            };
            WikiPage ret =  ...// parse the data to the WikiPage class
                            // this part takes less time but depend on the sync block above

            return ret;
        }
    }
}

@Kayaman 我不确定我是否理解您的评论，问题是我返回了一个未来。您对如何改进我的代码以更快地运行有什么建议吗？

Answer 1

不，信号量在这里没有用。它只知道它有多少许可，信号量中没有“索引”。

您可以改用AtomicIntegerArray，尽管如果您解释了您的根本问题，可能会有更合适的类可供使用。