Is there any way to say "switch back to caller thr...

# rx

[ghedeon]

Is there any way to say "switch back to caller thread"? For example, I want to wrap some callback call into a single, but the implementation of the callback is switching my thread to Main. As a result, the whole chain is now on the Main, which is not obvious, if you look at the declaration.
Ex:

....
   .map { single_that_switches_the_thread_to_Main() }
   .map {}  // <--- NOT io
  .subscribeOn(io)

So, I'd like to be able to tell to this single_that_switches_the_thread_to_Main() to switch to the caller thread, inside of it, not on the usage side.

[gsala]

is the caller thread the "io" thread since you have the subscribeOn(io)?

[ghedeon]

in this particular case yes, the caller thread is IO. The thing is, you can't do assumptions about caller thread when you create the Single inside single_that_switches_the_thread_to_Main()

[gsala]

so calling observeOn(io) after the single_... wouldn't do it because you are not sure the caller thread was io?

[ghedeon]

observeOn(io) does the trick of course. But it's a fix on the usage side. Let say I'm exposing this single_that_switches_thread. Now, I need to make sure to tell everybody "hey, warning, it fuck ups your chain, fix it with observeOn!". And then you have this hacks all over the code. I was wondering if it's possible to fix it on the creation side, in the provider of this single itself.

[rook]

You could have single_that_switches_thread exposed through a method that takes a “source thread” scheduler and then just call observeOn for the caller

[rook]

that way no one can have access to single_that_switches_thread without explicitly stating which thread it’s being called from

[ghedeon]

yes.. that would be the last resort. Was just curious if it's possible to make it to operate on a "non particular thread", like most of the rx operators do. Thank you!

[rook]

I’m not sure if I’m misunderstanding you, but there is a newThread scheduler.

[ursus]

no, if it applies its scheduler then you cannot undo it, just switch somewhere else once it emits