Class Persistence.createEntityManagerFactory() used in Verticle produced new Vertx Instance

[codingxu97]

Here is my code:

Console printed the following message:

[DavideD]

I'm working on the documentation of this part, but basically you need to register the already existing Vert.x instance when you create the SessionFactory.

I've explained how to do it as an answer to this question.

Let me know if that helps. I will add that section to the documentation before the final release

[codingxu97]

Thanks!
But I prefer using JPA Persistence instead of hibernate Configuration class,for it's simple and general.

[DavideD]

The service loader mechanism described in the answer should work with the JPA approach as well.

[codingxu97]

I tried to do this,but it not works.
Here is my code:

Then,run the code:

In addition,service loader seems to be used with classes which have a zero-argument constructor.

So,Class MyProvider in my code used default constructor.

ProvidedVertxInstance seems to be the best choice to use in service loader,but it has no zero-argument constructor.

[DavideD]

Please, it would be better if you could attach the code as preformatted text and not using images.

You don't show what the class MyProvider looks like so I cannot tell you why it doesn't work.
Also, you don't need to access the VertxInstance service.

These are the two approaches:

1. Create the factory programmatically:

   import org.hibernate.cfg.Configuration;
   
   public Stage.SessionFactory createFactory() {
       Configuration configuration = new Configuration();
       // ... set the values for your configuration 
   
      StandardServiceRegistryBuilder builder = new ReactiveServiceRegistryBuilder()
                               // Add the service that returns the current Vert.x instance
   			.addService( VertxInstance.class, (VertxInstance) () -> vertx )
   			.applySettings( configuration.getProperties() );
   
      StandardServiceRegistry registry = builder.build();
      return configuration.buildSessionFactory( registry )
          .unwrap( Stage.SessionFactory.class );
   }
   

UPDATED: I don't think the example I wrote initially for case 2 will work. I will test it and update the answer if I can find a better solution

2. Implementing the interface VertxInstace.
   I'm not sure exactly how to make this work in this case. The problem is that you need to define a class that can access the
   Vert.x instance in MainClass. I will think a bit more about it and let you know if I can find a solution

I guess in this case you should go with the first solution.

[DavideD]

Actually, I'm not sure the second approach will work. I will create a test and get back to you

[codingxu97]

Sorry,I will no longer use code images.

As you told,the second approach didn't work.

I used MainVerticle which implements VertxInstace instead of MyProvider.

class MainVerticle : CoroutineVerticle(), VertxInstance {  }

But,it still create a new Vertx instance When I run following code:

override suspend fun start() {
    val sessionFactoryAwait = vertx.executeBlocking<Stage.SessionFactory> {
        // Get SessionFactory
        val sf: SessionFactory =
            Persistence
                .createEntityManagerFactory("mysql-demo")
                .unwrap(SessionFactory::class.java)
        // Get VertxInstance via docs
        val vertxViaDoc: VertxInstance =
            sf.unwrap(SessionFactoryImplementor::class.java)
                .serviceRegistry
                .getService(VertxInstance::class.java)
        // Get VertxInstance via Service Loader
        val loaderViaSpi: ServiceLoader<VertxInstance> = ServiceLoader.load(VertxInstance::class.java)
        val vertxViaSpi: VertxInstance = loaderViaSpi.single()
    
        println(vertxViaDoc.javaClass.simpleName)
        println(vertxViaSpi.javaClass.simpleName)
    
        val stageSf = sf.unwrap(Stage.SessionFactory::class.java)
        it.complete(stageSf)
    }
    
    val sessionFactory: Stage.SessionFactory = sessionFactoryAwait.await()
}

Run result:

18:25:50.322 [vert.x-worker-thread-0] WARN io.vertx.core.impl.VertxImpl - You're already on a Vert.x context, are you sure you want to create a new Vertx instance?
DefaultVertxInstance
MainVerticle

Here is my MainClass code:

suspend fun main() {
    val vertx = Vertx.vertx()
    vertx
        .deployVerticle("com.fospot.trader.hibernatetest.MainVerticle")
        .await()
}

[DavideD]

I suppose you could try something like this:

suspend fun main() {
    val vertx = Vertx.vertx()
   MyProvider.vertx= vertx;
    vertx
        .deployVerticle("com.fospot.trader.hibernatetest.MainVerticle")
        .await()
}

public class MyProvider implements VertxInstance {
    public static Vertx vertx = null;

   @Override
   public void getVertx() {
       return vertx;
   }
}

But using the Hibernate configuration instead of the Persistence one looks better IMHO.

By the way, you can change the code to something more reactive by using this approach.

[codingxu97]

Thanks a lot!

On your suggestion,it still create new one.Maybe I should give up using Persistence.

But,is there any possibility that Hibernate reactive could support to use Persistence in Verticle in the future?It seems that persistence.xml was more general than hibernate.cfg.xml IMHO.

[DavideD]

On your suggestion,it still create new one.Maybe I should give up using Persistence.

That's weird, are you sure the service is defined correctly in your app? Does MyProvider get created and called?
If you could provide a test project I will check.

But,is there any possibility that Hibernate reactive could support to use Persistence in Verticle in the future?It seems that persistence.xml was more general than hibernate.cfg.xml IMHO.

The persistence.xml and the use of the class Persistence come from JPA JSR. This specification is not designed for reactive code and it doesn't define how to interact with Vert.x.

I think what we already have allows this already. How would you pass an instance of Vert.x in the persistence.xml?

[codingxu97]

Here is my demo:
https://github.com/Mr-CodingXu/hibernate-demo.git

By the way, first approach using hibernate.cfg.xml works, Thanks!

[DavideD]

I can see that the ServiceLoader is not loading MyProvider.

[codingxu97]

Here is run result:

20:26:08.654 [vert.x-worker-thread-0] WARN io.vertx.core.impl.VertxImpl - You're already on a Vert.x context, are you sure you want to create a new Vertx instance?
DefaultVertxInstance
MyProvider

So, MyProvider will be printed to the console when I invoke ServiceLoader.load(VertxInstance::class.java).single().

[DavideD]

Mmmh... I think you have found a bug

[codingxu97]

Oh, I see!

In fact, I'd read the source code roughly yesterday, it seems that VertxInstanceInitiator instantiates VertxInstance using DefaultVertxInstance class, and I couldn't find out where service loader changes it.

// Definitely exclusive to Hibernate Reactive, as it marks the registry as Reactive:
serviceInitiators.add( ReactiveMarkerServiceInitiator.INSTANCE );

// Exclusive to Hibernate Reactive:
serviceInitiators.add( VertxInstanceInitiator.INSTANCE );
serviceInitiators.add( VertxContextInitiator.INSTANCE );

// Exclusive to Hibernate Reactive:
serviceInitiators.add( SqlClientPoolConfigurationInitiator.INSTANCE );
serviceInitiators.add( ReactiveConnectionPoolInitiator.INSTANCE );

In addtion, here is the method start() in DefaultVertxInstance class:

@Override
public void start() {
    vertx = Vertx.vertx();
}

Could Vertx.currentContext().owner() be used instead of Vertx.vertx() like following code?

@Override
public void start() {
    Context currentContext = Vertx.currentContext();
    vertx = currentContext != null ? currentContext.owner() : Vertx.vertx();
}

[DavideD]

Could Vertx.currentContext().owner() be used instead of Vertx.vertx() like following code?

You know, I think that was the initial plan. @gavinking?
We could create it if there is no context and stop the service only in that case.

Anyway, I understand now why the service loader is not working.
I was loading the wrong service, I will publish the changes that work

[DavideD]

@Mr-CodingXu Would you like to send a PR about changing DefaultVertxInstance? Just make sure to stop vert.x only if we are the one that have created it

[DavideD]

Anyway, to register a custom VertxInstance using the java ServiceLoader the correct approach is to use a ServiceContributor:

package com.coding.demo.hibernate.provider

import org.hibernate.boot.registry.StandardServiceRegistryBuilder
import org.hibernate.reactive.vertx.VertxInstance
import org.hibernate.service.spi.ServiceContributor

class MyProviderContributor : ServiceContributor {
    override fun contribute(nullable: StandardServiceRegistryBuilder?) {
        var serviceRegistryBuilder = nullable!!
        serviceRegistryBuilder.addService(VertxInstance::class.java, MyProvider())
    }
}

and then regsiter it using the file:

/META-INF/services/org.hibernate.service.spi.ServiceContributor

I've forked the project you've provided and updated it on my repository: https://github.com/DavideD/hibernate-demo
Thanks a lot!

[codingxu97]

@Mr-CodingXu Would you like to send a PR about changing DefaultVertxInstance? Just make sure to stop vert.x only if we are the one that have created it

Oh, yes! I'll think it over and try to do it in the shortest time.

[codingxu97]

I've forked the project you've provided and updated it on my repository: https://github.com/DavideD/hibernate-demo Thanks a lot!

Your code refactoring offers me another train of thought for better code, thanks!

[DavideD]

Thanks :-)
I'm not familiar with Kotlin so I'm sure there is space for improvement.

I'm closing this issue. It seems we figure out what we need to improve.
I've created #1001 to keep track of the changes to DefaultVertxInstance.

Thanks a lot again!

[DavideD]

I've clened up the demo a bit more: DavideD/hibernate-demo@c7c96aa