Please consider supporting Java 8 Date/Time type when serializing with Kryo

[kennyliao1982]

Environment

• Dubbo version: 2.6.2
• Java version: 1.8

I am using java.time.LocalDateTime and Dubbo complains "class java.time.LocalDateTime has no zero-arg constructor and this will affect the serialization performance", which is caused by Dubbo's wrapper class "CompatibleKryo"

Any thoughts ??

package com.alibaba.dubbo.common.serialize.kryo;

import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.common.serialize.kryo.utils.ReflectionUtils;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.Serializer;
import com.esotericsoftware.kryo.serializers.JavaSerializer;

public class CompatibleKryo extends Kryo {

    private static final Logger logger = LoggerFactory.getLogger(CompatibleKryo.class);

    @Override
    public Serializer getDefaultSerializer(Class type) {
        if (type == null) {
            throw new IllegalArgumentException("type cannot be null.");
        }

        if (!type.isArray() && !type.isEnum() && !ReflectionUtils.checkZeroArgConstructor(type)) {
            if (logger.isWarnEnabled()) {
                logger.warn(type + " has no zero-arg constructor and this will affect the serialization performance");
            }
            return new JavaSerializer();
        }
        return super.getDefaultSerializer(type);
    }
}

[jtanza]

hi, I haven't contributed before but would like to take this one on, is that okay? I am not actually sure of how to best address this one, but may get a better handle on things after taking a closer look at this portion of the code

[beiwei30]

@jtanza, feel free to give it a try, pls. submit a pull request once you finish it :)

[jtanza]

Awesome, will do!

[chickenlj]

I think this snippet works, only too much warn logs, is that right?

if (!type.isArray() && !type.isEnum() && !ReflectionUtils.checkZeroArgConstructor(type)) {
            if (logger.isWarnEnabled()) {
                logger.warn(type + " has no zero-arg constructor and this will affect the serialization performance");
            }
            return new JavaSerializer();
        }

[chickenlj]

It seems that Kryo 4.0.1 used by Dubbo already support Java 8 Date types. It's the CompatibleKryo short-circuited that logic by checking zero-arg constructor.

[kennyliao1982]

Thank you all guys for working on this issue.
May I know what's the plan to release this fix??