Application tips for decrypting Guava cache: an artifact to improve application performance

Guava cache usage tips

Guava cache is a high-performance memory cache that can significantly improve application performance. It provides a variety of caching strategies, and you can choose the most appropriate caching strategy according to different scenarios.

Basic use of Guava cache

The basic use of Guava cache is very simple and only requires a few lines of code.

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

public class GuavaCacheExample {

    public static void main(String[] args) {
        // 创建一个缓存，最大容量为100个元素，过期时间为10秒
        LoadingCache<String, String> cache = CacheBuilder.newBuilder()
                .maximumSize(100)
                .expireAfterAccess(10, TimeUnit.SECONDS)
                .build(new CacheLoader<String, String>() {
                    @Override
                    public String load(String key) {
                        // 从数据库中加载数据
                        return loadFromDatabase(key);
                    }
                });

        // 将数据放入缓存中
        cache.put("key1", "value1");

        // 从缓存中获取数据
        String value = cache.get("key1");

        // 判断缓存中是否存在数据
        boolean exists = cache.getIfPresent("key1") != null;
    }

    private static String loadFromDatabase(String key) {
        // 模拟从数据库中加载数据
        return "value" + key;
    }
}

Caching strategy of Guava cache

Guava cache provides a variety of caching strategies, and you can choose the most appropriate caching strategy according to different scenarios.

Size-based caching strategy

Size-based caching strategy refers to deciding whether to put data into the cache based on the size of the cache. Guava cache provides two size-based caching strategies:

• maximumSize(): Set the maximum capacity of the cache. When the cache reaches maximum capacity, the oldest data put into the cache will be evicted.
• weigher(): Set the cache weight function. The weight function can calculate the weight of data based on its size or other factors. When the cache reaches its maximum capacity, the data with the greatest weight will be evicted.

Time-based caching strategy

The time-based caching strategy refers to deciding whether to put data into the cache based on the expiration time of the data. Guava cache provides two time-based caching strategies:

• expireAfterWrite(): Set the expiration time of data in the cache. When the data stored in the cache exceeds the expiration time, it will be eliminated.
• expireAfterAccess(): Set the expiration time after the data is accessed in the cache. When the data is accessed in the cache, the expiration time is recalculated.

Reference-based caching strategy

Reference-based caching strategy refers to deciding whether to put data into the cache based on the reference count of the data. Guava cache provides two reference-based caching strategies:

• weakKeys(): Set cache keys to weak references. When a key is garbage collected, the data in the cache will be evicted.
• softValues(): Set cached values ​​to soft references. When a value is garbage collected, the data in the cache is evicted.

Tips for using Guava cache

When using Guava cache, you can pay attention to the following points:

• Choose the appropriate caching strategy: Choose the most appropriate caching strategy according to different scenarios.
• Set the cache capacity reasonably: The cache capacity should not be too large, otherwise it will occupy too much memory.
• Set the expiration time reasonably: The expiration time should not be too long, otherwise the data in the cache may become invalid.
• Pay attention to concurrent access to the cache: If the cache is accessed by multiple threads at the same time, you need to consider the concurrency control of the cache.
• Clear the cache regularly: Cleaning the cache regularly can prevent the data in the cache from becoming outdated.

Conclusion

Guava cache is a high-performance memory cache that can significantly improve application performance. Through reasonable use of Guava cache, the performance and scalability of the application can be effectively improved.

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