RedisTemplate pipline

when a job need to update alot redis k/v
use normal command loop is low efficiency plan
that cause tcp connection time-wait exceed several ten thousand.
so we use redis pipline operation merge command connection.

Use RedisTemplate read obj

Set User class deserializer first

private static final Jackson2JsonRedisSerializer userSerializer = new Jackson2JsonRedisSerializer(User.class);
redisTemplate.setValueSerializer(userSerializer);

pip execute multi get command

List<User> result = redisTemplate.executePipelined(new RedisCallback<List<User>>() {
    @Override
    public List<User> doInRedis(RedisConnection connection) throws DataAccessException {
        for (Object obj: keys)
            connection.get((RedisConstant.USER + obj).getBytes());
        return null;
    }
}, redisTemplate.getValueSerializer());

Use RedisTemplate write obj

Same as above use User class serializer first

private static final Jackson2JsonRedisSerializer userSerializer = new Jackson2JsonRedisSerializer(User.class);
userSerializer.serialize(user);

pip execute multi set command

redisTemplate.executePipelined(new RedisCallback<List>() {
    @Override
    public List doInRedis(RedisConnection connection) throws DataAccessException {
        for (Map.Entry<byte[], byte[]> entry : map.entrySet())
            connection.set(entry.getKey(), entry.getValue());
        return null;
    }
});

Caution

1. connection return is byte array, it need deserializer method.

2. doInRedis return must be null, the return value has been take over by executePipelined.

   if (result != null)
     throw new InvalidDataAccessApiUsageException(
       "Callback cannot return a non-null value as it gets overwritten by the pipeline");

3. don’t call connection.closePipeline(), it will return result and no deserialize.

4. Deserialize need deserializer object. like these
   

https://blog.csdn.net/xiaoliu598906167/article/details/82218525
https://blog.csdn.net/huilixiang/article/details/19484921
https://blog.csdn.net/xiaolyuh123/article/details/78682200
https://my.oschina.net/yuyidi/blog/499951
https://www.cnblogs.com/EasonJim/p/7803067.html#autoid-2-6-0