I'm trying to run x number of async operations and then combine the results when the async operation...

# coroutines

[Dave Jensen]

I'm trying to run x number of async operations and then combine the results when the async operations are all done. Kinda like Promises.all

[Dave Jensen]

Here's a convoluted example but it should get the point across:

[Dave Jensen]

Untitled

[octylFractal]

there's an extension function for List<Deferred<T>>, awaitAll(): List<T>

[Dave Jensen]

Awesome, thanks!

[Dave Jensen]

My followup question, is this the "best" way of doing this? Or is another technique more idiomatic?

[octylFractal]

if you specifically want them to be async, then this is probably the simplest way

[octylFractal]

depending on how complicated it gets, Flow may be useful, but it doesn't yet have good concurrency primitives, it's best for serial processing. You can emulate concurrent processing by using .map { async { } } and .buffered, but it's certainly more complex than this

[Dave Jensen]

What if getInt contains a blocking call? Like an http library that doesn't support coroutines?

[octylFractal]

you should wrap it with a suspend function + withContext(<http://Dispatchers.IO|Dispatchers.IO>), e.g.:

suspend fun suspendGetInt(i: Int) = withContext(<http://Dispatchers.IO|Dispatchers.IO>) { getInt(i) }

[octylFractal]

if you have e.g. callbacks, other async tools, there are more efficient ways to wrap those as well

[octylFractal]

but if the only option is to block, this is the solution

[Dave Jensen]

We're kinda stuck with what Swagger generates for us. Still looking for a swagger code-gen that supports coroutines.

[Dave Jensen]

What if we have a callback (or even a Promise)?

[octylFractal]

https://medium.com/@elizarov/callbacks-and-kotlin-flows-2b53aa2525cf#130e

[Dave Jensen]

Thank you!

[octylFractal]

I think you can do something similar with a Promise (.then is basically a callback)