Shulou(Shulou.com)05/31 Report--

This article is about how to use LinkedHashMap to build FIFO and LRU cache systems. The editor thinks it is very practical, so I share it with you. I hope you can get something after reading this article.

For caching, I believe many people are no stranger to it. In general, for some commonly used data, basic data, etc., or for high concurrency, such as panic buying, put hot data into the cache to achieve high concurrency and fast response.

When it comes to caching, Redis, memcached and so on are necessary knowledge points in the interview. Although these specialized caching systems are powerful and complex, the underlying principle is actually very simple. Today we are going to build two caching systems with FIFO and LRU mechanisms through LinkedHashMap.

FIFO is easy to understand, which is First In First Out, first in, first out. Like the queue, the first-out queue of the first-in queue. According to the characteristics of this FIFO, we can implement the caching system of this mechanism through LinkedHashMap.

The above lines of code take care of the caching of the FIFO mechanism. The test code is also simple, as follows:

A screenshot of the test result is shown below:

From the above test results, we can see that the cache system is not perfect. When I update the element, I want it to be reinserted into the queue, which is equivalent to re-joining the queue. Because it has just been updated, it may be used more frequently. As a result, LRU, this cache elimination mechanism, was applied.

LRU is (Least Recently Used), which is the least used recently, meaning that the recently read data comes first and the earliest read data comes last. If new data comes in at this time, when there is not enough cache space, the last stored data will be eliminated. The implementation code is as follows:

Let's take a look at the test code:

The screenshot of the running effect is as follows:

The above is how to use LinkedHashMap to build FIFO and LRU cache systems. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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