开源框架编码技巧一(缓存设计篇)

原创

已于 2023-11-04 12:36:27 修改 · 389 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#缓存 #java

于 2023-05-03 22:09:07 首次发布

文章介绍了Nacos中缓存的设计，包括Cache接口及其通用缓存项配置，展示了SimpleCache、AutoExpireCache（实现过期清理）、SynchronizedCache（线程安全）和LruCache（LRU缓存）四种不同的实现方式，以及如何通过CacheBuilder构建不同特性的缓存。

一、本地缓存设计

1、Nacos的缓存结构设计为例,通用缓存为例,支持不同模式的缓存，

支持更复杂功能，可以直接使用Guava和Caffine直接使用.

①、Cache缓存接口.

package com.alibaba.nacos.common.cache;

import java.util.concurrent.Callable;

/**
 * Cache method collection definition.
 * @author zzq
 * @date 2021/7/30
 */
public interface Cache<K, V> {

    /**
     * Cache a pair of key value. If the key value already exists, the value will be overwritten.
     * @param key cache key
     * @param val cache value
     */
    void put(K key, V val);
    
    /**
     * Take the corresponding value from the cache according to the cache key.
     * @param key cache key
     * @return cache value
     */
    V get(K key);
    
    /**
     * Get the value in the cache according to the primary key, and put it into the cache after processing by the function.
     * @param key cache key
     * @param call a function, the return value of the function will be updated to the cache
     * @return cache value
     * @throws Exception callable function interface throw exception
     */
    V get(K key, Callable<? extends V> call) throws Exception;
    
    /**
     * Take the corresponding value from the cache according to the cache key, and remove this record from the cache.
     * @param key cache key
     * @return cache value
     */
    V remove(K key);
    
    /**
     * Clear the entire cache.
     */
    void clear();
    
    /**
     * Returns the number of key-value pairs in the cache.
     * @return  number of key-value pairs
     */
    int getSize();
}

②、CacheItemProperties【通用缓存项配置】

package com.alibaba.nacos.common.cache.builder;

/**
 * Cache item's own attributes.
 * @author zzq
 * @date 2021/7/30
 */
public class CacheItemProperties {
    
    private long expireNanos;
    
    public long getExpireNanos() {
        return expireNanos;
    }
    
    public void setExpireNanos(long expireNanos) {
        this.expireNanos = expireNanos;
    }
}

2、缓存实现

①、SimpleCache，不带任何功能.

package com.alibaba.nacos.common.cache.impl;

import com.alibaba.nacos.common.cache.Cache;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.Callable;

/**
 * Simple implementation of {@code Cache}.
 * @author zzq
 * @date 2021/7/30
 */
public class SimpleCache<K, V> implements Cache<K, V> {
    
    private Map<K, V> cache;