Redis CacheClient

This tool solves Redis Cache breakdown of 、 Cache penetration 、 Caching avalanches , For more information, refer to generics and Function Use ！ A very good way ！

Be careful , The following code depends on Hutool tool kit , And references to several character constants , Change to any character by yourself ！

Introduce ：

 Cache breakdown  queryWithPassThrough
 Cache penetration  queryWithMutex
 Cache avalanche  queryWithLogicalExpire

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import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

@Slf4j
@Component //  register as IOC Container of Bean, Use direct Autowired
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    //  Define a thread pool , It is convenient to open threads to perform operations 
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    //  Add one String Key value pairs of type 
    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    //  Set logical expiration Key, To avoid cache breakdown 
    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        //  Set logical expiration 
        HashMap<String, Object> hashMap = new HashMap();
        hashMap.put("data", value);
        hashMap.put("expireTime", LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //  write in Redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(hashMap));
        /**
         RedisData redisData = new RedisData();
         //redisData.setData(value);
         //redisData.setExpireTime();
         //  write in Redis
         stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
         **/
    }

    //  Cache penetration solution ： Normal query , Walk normally . If DB No data , Insert with TTL Null value of 
    public <R, ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        // 1. from redis Query store cache 
        String json = stringRedisTemplate.opsForValue().get(key);
        // 2. Judge whether it exists 
        if (StrUtil.isNotBlank(json)) {
            // 3. There is , Go straight back to 
            return JSONUtil.toBean(json, type);
        }
        //  Determine whether the hit is null 
        if (json != null) {
            //  Return an error message 
            return null;
        }
        // 4. non-existent , according to id Query the database 
        R r = dbFallback.apply(id);
        // 5. non-existent , Returns an error 
        if (r == null) {
            //  Write null values to redis
            stringRedisTemplate.opsForValue().set(key, "", 5, TimeUnit.MINUTES);
            //  Return error message 
            return null;
        }
        // 6. There is , write in redis
        this.set(key, r, time, unit);
        return r;
    }

    //  Cache avalanche solution ： Query logic expired , If it's out of date , Then reinsert it 
    public <R, ID> R queryWithLogicalExpire(
            String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        // 1. from redis Query store cache 
        String json = stringRedisTemplate.opsForValue().get(key);
        // 2. Judge whether it exists 
        if (StrUtil.isBlank(json)) {
        // 3. There is , Go straight back to 
            return null;
        }
        // 4. hit , Need first json Deserialize to object 
        HashMap<String,Object> hashMap = JSONUtil.toBean(json, HashMap.class);
        R r = JSONUtil.toBean((JSONObject) hashMap.get("data"), type);
        /**
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
         **/
        LocalDateTime localDateTime = LocalDateTime.parse((CharSequence) hashMap.get("expireTime"), DateTimeFormatter.ofPattern("yyyy-MM-dd E HH:mm:ss"));
        // 5. Judge whether it is overdue , Using pure JDK Tools for 
        if (localDateTime.isAfter(LocalDateTime.now())) {
            // 5.1. Not expired , Directly return the store information 
            return r;
        }
        // 5.2. Has expired , Cache rebuild required 
        // 6. Cache rebuild 
        // 6.1. Get mutex 
        String lockKey = "LOCK_SHOP_KEY" + id;
        boolean isLock = tryLock(lockKey);
        // 6.2. Judge whether the lock is obtained successfully 
        if (isLock) {
            // 6.3. success , Turn on independent threads , Realize cache reconstruction 
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //  Query the database 
                    R newR = dbFallback.apply(id);
                    //  Rebuild cache 
                    this.setWithLogicalExpire(key, newR, time, unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //  Release the lock 
                    unlock(lockKey);
                }
            });
        }
        // 6.4. Return expired shop information 
        return r;
    }

    //  Cache avalanche solution ： The mutex ： I will call myself , If Key non-existent , Then only one thread performs the insertion DB operation 
    public <R, ID> R queryWithMutex(
            String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        // 1. from redis Query store cache 
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2. Judge whether it exists 
        if (StrUtil.isNotBlank(shopJson)) {
            // 3. There is , Go straight back to 
            return JSONUtil.toBean(shopJson, type);
        }
        //  Determine whether the hit is null 
        if (shopJson != null) {
            //  Return an error message 
            return null;
        }
        // 4. Realize cache reconstruction 
        // 4.1. Get mutex 
        String lockKey = "Operate:AddLock" + id;
        R r = null;
        try {
            boolean isLock = tryLock(lockKey);
                // 4.2. Judge if you are successful 
            if (!isLock) {
                // 4.3. Lock acquisition failed , Hibernate and try again 
                Thread.sleep(50);
                return queryWithMutex(keyPrefix, id, type, dbFallback, time, unit);
            }
            // 4.4. Lock acquired successfully , according to id Query the database 
            r = dbFallback.apply(id);
            // 5. non-existent , Returns an error 
            if (r == null) {
                //  Write null values to redis
                stringRedisTemplate.opsForValue().set(key, "", 5, TimeUnit.MINUTES);
            //  Return error message 
                return null;
            }
            // 6. There is , write in redis
            this.set(key, r, time, unit);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // 7. Release the lock 
            unlock(lockKey);
        }
        // 8. return 
        return r;
    }

    //  Try to lock 
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    //  Unlock 
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }
}

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