如何在 EHCache 实例中使用元素版本控制？

发布于 2024-09-07 06:22:33 字数 956 浏览 6 评论 0原文

我正在缓存以异步方式发送到我的组件的对象。换句话说，这些对象到达的顺序是不可预测的。为了避免任何问题，我在我的对象中包含了一个版本属性（基本上是一个时间戳）。这个想法是，任何到达的对象的版本早于已缓存的版本，都可以被丢弃。

EHCache 的“Element”类（将对象包装在 EHCache 中）似乎促进了这一点：除了键和值之外，构造函数还可以采用（基于长的）版本。但我无法让这项工作按照我期望的方式进行。以下代码片段演示了我的问题（使用 EHCache 2.1.1）：

public static void main(String[] args) {
    final CacheManager manager = CacheManager.create();
    final Cache testCache = new Cache(new CacheConfiguration("test", 40));
    manager.addCache(testCache);

    final String key = "key";
    final Element elNew = new Element(key, "NEW", 2L);
    testCache.put(elNew);
    final Element elOld = new Element(key, "OLD", 1L);
    testCache.put(elOld);

    System.out.println("Cache content:");
    for (Object k : testCache.getKeys()) {
        System.out.println(testCache.get(k));
    }
}

我希望上面的代码会导致缓存的值成为“NEW”，而不是打印“OLD”。如果您稍微调整一下元素的插入顺序，您会发现最后插入的元素将保留在缓存中。版本控制似乎被忽略了。

我是否没有正确使用版本控制功能，或者它可能不打算用于此目的？有人可以推荐替代品吗？

原文

I am caching objects that are being sent to my component in an asynchronous way. In other words, the order in which these objects arrive is unpredictable. To avoid any issues, I have included a version attribute to my objects (which basically is a timestamp). The idea is that any object that arrives with a version that's older than the one that has already been cached, it can be discarded.

The "Element" class of EHCache (which wraps objects in an EHCache) seems to facilitate this: apart from a key and value, the constructor can take a (long-based) version. I cannot make this work in the way I'd expect it to work though. The following code snippet demonstrates my problem (Using EHCache 2.1.1):

public static void main(String[] args) {
    final CacheManager manager = CacheManager.create();
    final Cache testCache = new Cache(new CacheConfiguration("test", 40));
    manager.addCache(testCache);

    final String key = "key";
    final Element elNew = new Element(key, "NEW", 2L);
    testCache.put(elNew);
    final Element elOld = new Element(key, "OLD", 1L);
    testCache.put(elOld);

    System.out.println("Cache content:");
    for (Object k : testCache.getKeys()) {
        System.out.println(testCache.get(k));
    }
}

I'd expect the code above to cause the cached value to be "NEW", instead, "OLD" is printed. If you play a bit with the order in which elements are inserted, you'll find that the last one that has been inserted is the one that will remain in cache. Versioning seems to be ignored.

Am I not using the versioning-feature properly, or is it perhaps not intended to be used for this purpose? Can anyone recommend alternatives?

分享到QQ

分享到微博