如何从信号量中获取获取的索引

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格。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 我不确定我理解你的评论，问题是我 return 一个未来。您对如何将我的代码改进到运行更快有什么建议吗？

Answer 1

不，信号量在这里没有用。它只知道它有多少个许可，信号量中没有"indices"。

您可以改用 AtomicIntegerArray，但如果您解释了根本问题，可能会有更适合使用的 class。

如何从信号量中获取获取的索引

how to get the acquired index from Semaphore

java

multithreading

semaphore

thread-safety