如何在Java中实现LRU缓存？ [英] How would you implement an LRU cache in Java?

问题描述

请不要说EHCache或OSCache等。假设为了这个问题的目的，我想使用SDK实现自己的（通过做）。鉴于缓存将在多线程环境中使用，您将使用哪些数据结构？我已经使用 LinkedHashMap 实现了一个 Collections＃synchronizeMap ，但是如果任何新的并发集合将是更好的候选人，我很好奇。

Please don't say EHCache or OSCache, etc. Assume for purposes of this question that I want to implement my own using just the SDK (learning by doing). Given that the cache will be used in a multithreaded environment, which datastructures would you use? I've already implemented one using LinkedHashMap and Collections#synchronizedMap, but I'm curious if any of the new concurrent collections would be better candidates.

更新：我只是通过 Yegge的最新的，当我发现这个矿块：

UPDATE: I was just reading through Yegge's latest when I found this nugget:

如果您需要定时访问并希望维护插入顺序，那么您不能比LinkedHashMap更好，这是一个真正精彩的数据结构。唯一可能会更美妙的是如果有并发版本。但是唉，

If you need constant-time access and want to maintain the insertion order, you can't do better than a LinkedHashMap, a truly wonderful data structure. The only way it could possibly be more wonderful is if there were a concurrent version. But alas.

在我与 LinkedHashMap + Collections＃synchronizeMap 我上面提到的实现。很高兴知道我不只是忽略了一些东西。

I was thinking almost exactly the same thing before I went with the LinkedHashMap + Collections#synchronizedMap implementation I mentioned above. Nice to know I hadn't just overlooked something.

根据迄今为止的答案，听起来好像我最好的选择是高度并发的LRU将会扩展 ConcurrentHashMap 使用一些相同的逻辑 LinkedHashMap 使用。

Based on the answers so far, it sounds like my best bet for a highly concurrent LRU would be to extend ConcurrentHashMap using some of the same logic that LinkedHashMap uses.

推荐答案

如果我今天再次从头开始，我会使用Guava的 CacheBuilder 。

If I were doing this again from scratch today, I'd use Guava's CacheBuilder.

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