使用RedisAtomicLong优化性能

前言

在项目中许多过这样的需求，记录留做备忘。
需要创建一个递增序列，这个序列会提供给多个应用来使用，这样就需要保持序列的原子递增。

RedisAtomicLong

spring-data-redis包中提供的，可以对数据中的Long类型进行原子性操作的类，下面是这个类的头：

/**
 * Atomic long backed by Redis. Uses Redis atomic increment/decrement and watch/multi/exec operations for CAS
 * operations.
 *  * @see java.util.concurrent.atomic.AtomicLong
 * @author Costin Leau
 * @author Thomas Darimont
 * @author Christoph Strobl
 * @author Mark Paluch
 */
public class RedisAtomicLong extends Number implements Serializable, BoundKeyOperations<String> {

我们可以看到java.util.concurrent.atomic.AtomicLong，和java自带的atomic包一样进行原子性操作，两者不同的是：

• AtomicLong只能在一个应用中使用
• RedisAtomicLong可以在所有与Redis有连接的应用中使用

开始优化

应用初始化时创建RedisAtomicLong实例。

 //
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package com.jiu.common.redis;

import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.support.atomic.RedisAtomicLong;

public class RedisSequenceFactory {
    private static final Logger log = LoggerFactory.getLogger(RedisSequenceFactory.class);
    @Autowired
    private ObjectRedisTemplate<Integer> redisTemplate;

    public RedisSequenceFactory() {
    }

    public void set(String key, long value) {
        RedisAtomicLong counter = new RedisAtomicLong(key, this.redisTemplate.getConnectionFactory());
        counter.set(value);
    }

    public long generate(String key, int increment) {
        RedisAtomicLong counter = new RedisAtomicLong(key, this.redisTemplate.getConnectionFactory());
        return counter.addAndGet((long)increment);
    }

    public List<Long> generateBatch(String key, int increment, int size) {
        RedisAtomicLong counter = new RedisAtomicLong(key, this.redisTemplate.getConnectionFactory());
        long max = counter.addAndGet((long)(increment * size));
        long min = max - (long)(increment * (size - 1));
        List<Long> list = new ArrayList();
        list.add(min);

        for(int i = 1; i < size; ++i) {
            list.add(min + (long)(increment * i));
        }

        return list;
    }

    public long queryValue(String key) {
        Integer val = (Integer)this.redisTemplate.get(key);
        return val == null ? 0L : (long)val.intValue();
    }
}

测试代码

public static String tradeIdIncRedisKey = "order:orderid_inc";
     @Test
    public long generateId(){
        return redisSequenceFactory.generate(tradeIdIncRedisKey,1);
    }