I want `scanAudios ` and `scanVideos ` to execute first befo

Question

I want `scanAudios ` and `scanVideos ` to execute first before other stuff in this function ``` private suspend fun getFolderDataList List lt FolderData gt thisScope async scanAudios scanVideos await val audioFolderData = viewModel getAudioUris map uri gt FolderData Audio uri val videoFolderData = viewModel getVideoUris map uri gt FolderData Video uri return audioFolderData plus videoFolderData ``` Am I doing it correctly

Dominaezzz · Answer

Short answer is yes

Dominaezzz · Answer

I m a little sceptical about the immediate `await` after the `async` but it should do what you want

Dominaezzz · Answer

Why have you used `async` there

The Monster · Answer

I needed the function `await ` `launch ` does not have it `launch ` only has `invokeOnCompletion ` which I cannot use because the other code are also suspend functions

Dominaezzz · Answer

`launch` has `join`

Dominaezzz · Answer

Why not just call `scanAudios` and `scanVideos` without wrapping it in a coroutine

The Monster · Answer

oh I didn t know of `join` Let me check it out

The Monster · Answer

`scanAudios` and `scanVideos` need to complete first for the code after to be accurate

Dominaezzz · Answer

Sure but you can do that without wrapping them

Dominaezzz · Answer

The wrapping you ve added there doesn t change anything with regards to ordering

The Monster · Answer

oh how do I wait for them without the `join` or `await` then

Dominaezzz · Answer

``` private suspend fun getFolderDataList List lt FolderData gt scanAudios scanVideos val audioFolderData = viewModel getAudioUris map uri gt FolderData Audio uri val videoFolderData = viewModel getVideoUris map uri gt FolderData Video uri return audioFolderData plus videoFolderData ```

Dominaezzz · Answer

What do you mean by wait What does `scanAudios` do It s a suspend function right

The Monster · Answer

are you sure `getAudioUris ` and `getVideoUris ` won t be executed when `scanAudios` `scanVideos` are running

The Monster · Answer

yes `scanAudios` is a suspend function `getAudioUris` and `getVideoUris` are also suspend

Dominaezzz · Answer

Yes suspend functions suspend the coroutine when they are called You only get concurrency when you introduce it with `launch` or `async`

The Monster · Answer

wait here means I want `scanAudios` and `scanVideos` to finish first before calls to `getAudioUris` and `getVideoUris`

The Monster · Answer

ohh

Dominaezzz · Answer

Do you also want scanAudios and scanVideos to run at the same time

The Monster · Answer

Thanks for the help I haven t used coroutines for a while I must have confused between concurrency and suspension

The Monster · Answer

yes I want them to run at the same time

Dominaezzz · Answer

Ah in that case

Dominaezzz · Answer

``` private suspend fun getFolderDataList List lt FolderData gt coroutineScope launch scanAudios launch scanVideos val audioFolderData = viewModel getAudioUris map uri gt FolderData Audio uri val videoFolderData = viewModel getVideoUris map uri gt FolderData Video uri return audioFolderData plus videoFolderData ```

The Monster · Answer

perfect Thanks Your code helps this part of the doc makes more sense now <https kotlinlang org docs composing suspending functions html concurrent using async>

Joffrey · Answer

Calling suspend functions is like regular functions they don t return until they re done Using `async await ` is pointless and actually equivalent to just calling the functions The only difference here is you re using a particular scope so the coroutine context could be different but in terms of what waits and what doesn t it s equivalent

Joffrey · Answer

If you want to call `scanAudios` and `scanVideos` concurrently it s another story But it doesn t seem to be your goal here so you can keep things very simple