Rewrite async modules to non-experimental coroutines

[czyzby]

Experimental coroutine APIs are deprecated and yield errors in Kotlin 1.3.

[czyzby]

ktx-async uses some APIs deprecated as of 0.26.1. The full test suite passes for now, though.

[lokeshj]

@czyzby Now that coroutines are 1.0, could you please take a look at this again?

[czyzby]

@lokeshj Sure, but probably no sooner than this weekend.

[jcornaz]

ktxAsync should be an extension on CoroutineScope as well to be consistant with other coroutine builders of kotlinx.coroutines and to make life-cycle mangements easier.

[czyzby]

The develop branch is compatible with 1.0.1 coroutines API as of merging #170, although I still think ktx-async should be rewritten to leverage new coroutine APIs. See #169.

[jcornaz]

I know it is likely to be solved when you'll rewrite the async module, but I'd like to report here a bug I've fount using 3.9.9-SNAPSHOT today: AssetStorage.load is not thread safe.

Example:

ktxAsync {
  val texture1 = async { assetStoreage.load<Texture>("texture1.png") }
  val texture2 = async { assetStoreage.load<Texture>("texture2.png") }

  addScreen(MyScreen(texture1.await(), texture2.await())
  setScreen<MyScreen>()
}

With the code above, I experienced visual glitch like inverted textures, or getting only partial or scaled texture. Removing usages of async solved the problem.

Thread safety is an implicit contract of any suspend function. If necessary the function may use Mutex.withLock, withContext or channels to achieve its thread safety. But I always expect from a suspending function to be callable from any context.

[czyzby]

I know, the new solution uses a single assets mutable collection protected by a Mutex.

[czyzby]

Just wanted to let you know that I'm currently dealing with work and the end of semester at my uni, so I had to postpone this "a little". I should be done in a few weeks.

[czyzby]

@jcornaz I finished the documentation of the new ktx-async module and pushed the overhaul to the develop branch. I decided to remove the AssetStorage, since I don't think it should be strictly connected with the core coroutines utilities and I have to admit I'm not done with that one yet. Could you take a look at the new API?

[czyzby]

I'm closing this issue for now, AssetStorage will be implemented separately in 1.9.9-b2.

#182