is subscribe().with() blocking?

[rafaeltuelho]

Hi!

When I create a Mutiny and subscribe to it in the middle of a method like the one below, is this blocking equivalent to await() and also considered an antipattern?

public void addPower(Power power) {
  powers.add(power);
  Mutiny.fetch(power.getHeroes())
      .onItem()
      .invoke((heroes) -> power.getHeroes().add(this))
      .subscribe().with((heroes) -> logger.debugf("Hero (%s)<->Power(%s) association updated", this.getName(), power.getName()));
}

thanks in advance.

[Ladicek]

It is not blocking (AFAIK), but it is kinda "fire and forget". The caller can't know when the process completes, which might be OK or not. You also don't handle possible errors, which again might be OK or not.

[rafaeltuelho]

Got it! Any good practices for such a scenario when you need to call async ops without chaining to other Uni?

[jponge]

You can also add an error handler (2nd parameter) and a completion handler (3rd parameter) to .subscribe().with().

So the subscription triggers some async processing, and you would typically handle at least a success and a failure by passing 2 lambdas. I wouldn't consider it an anti-pattern: that's typically what you would do in pure Vert.x for instance. The key is to always care about errors.

• If you have async operations that shall happen in sequence, then you should .chain them.
• If you need to trigger multiple concurrent async operations you might find combining / joining them useful.

[rafaeltuelho]

Perfect! Thanks for clarifying, @jponge