ReactiveMailer not working

[Neonell]

Describe the bug

ReactiveMailer Email are not send or logged anymore.

The normal Mailer service is working fine.

Expected behavior

ReactiveMail send Method with or without attachment should send an email or log the email content in mock modus.

Actual behavior

ReactiveMail send Method with or without attachment is returning without doing anything. The Mail is never sent.
I implemented both, the non reactive version is working fine, Email are logged or sent when the mock mode is disabled.

How to Reproduce?

1. Create a new service in Quarkus 3.2+

     private final Mailer mailer;
	private final ReactiveMailer reactiveMailer;

	public Uni<Void> sendEmail(String to, String subject, String content) {
		return reactiveMailer.send(
				Mail.withHtml(
						to,
						subject,
						content
				)
		);
	}


	public Void sendEmailNormal(String to, String subject, String content) {
		mailer.send(
				Mail.withHtml(
						to,
						subject,
						content
				)
		);
		return null;
	}

2. Call the Methods, sendEmailNormal is working, either logging or actually sending the email, the sendEmail Method never send or log anything, just return after the toMailMessage() from the MutinyMailerImpl is called without calling the actual send method. The same method is called by the sendEmailNormal and after the toMailMessage() actually call the send method as expected.
3. Somehow the send method chained is not called by reactive call.

Output of uname -a or ver

Linux nbdvb144 5.19.0-50-generic #50-Ubuntu SMP PREEMPT_DYNAMIC Mon Jul 10 18:24:29 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

Output of java -version

openjdk version "17.0.6" 2023-01-17

GraalVM version (if different from Java)

No response

Quarkus version or git rev

3.2.2.Final

Build tool (ie. output of mvnw --version or gradlew --version)

Apache Maven 3.8.8

Additional information

No response

[quarkus-bot]

/cc @cescoffier (mailer)

[gastaldi]

How are you performing the call to the reactive API? Are you subscribing to the returned Uni<Void>?

[Neonell]

Hello @gastaldi ,

No I don't do it explicitly, I'm using the CountDownLatch Class in order to wait for the operation to complete in my test:

                CountDownLatch latch = new CountDownLatch(1);
		// Call the asynchronous method
		mailService.sendEmail(TO, SUBJECT, HTML_CONTENT);

		// Wait for the asynchronous operation to complete
		boolean completed = latch.await(2, TimeUnit.SECONDS);
		Assertions.assertTrue(completed);

This is not a rest endpoint but an internal Service that should be called when needed to notify user about different actions. Maybe that's the difference and I'm pretty new to Asynchronous programming. For now I just tried to write a test, then I tried to bind the method in a Synchronous Rest Endpoint and I wrotted an Asynchronous Document upload and download solution but throug a rest endpoint. Maybe that's the difference.

Thank you for the response I'm gonna read about subscription in java. I know the subscribe mechanisms from Angular but not the one from Java.

And the solution was in the subscrition:

mailService.sendEmail(TO, SUBJECT, HTML_CONTENT).subscribe().with(
				(item) -> latch.countDown()
		, failure -> {
			// Handle any failure if needed
		});

It works now, and I understand why the call was never made. Sorry for that :(

Cheers,
Frédéric

[gastaldi]

You're welcome! If you have any problems, feel free to start a discussion thread at https://github.com/quarkusio/quarkus/discussions instead ;)

[Neonell]

Oh merci beaucoup, that's really nice I'm pretty new flying out of the wildfly world to the quarkus one. It's really good to know. And yeah I can almost guess that the powerfull Resteasy library auto-scan Rest resources to identify the async one. It probably auto-create some subscription when a rest call is received.

Next time I ask in the discussions topic instead. Thank you for beeing nice :) I wish you all the best!