Configure resolver to generate resolver context

[kxl-adsk]

Address issue reported by #1236. FWIW. We are still planning on exploring Ar 2.0 so things may change here.

[kxl-adsk]

@dj-mcg @fabal @pmolodo Please review and raise concerns.

[dolivares-spinvfx]

Might this be another relevant location?

https://github.com/Autodesk/maya-usd/blob/dev/lib/mayaUsd/utils/utilFileSystem.cpp#L57

[dj-mcg]

Looks good, thanks!

[fabal]

That's a good thing to have 👍

Did you consider using ResolverContext objects too?
Typically in places like this where a call like ArGetResolver().CreateDefaultContextForAsset(fileString) has become the default standard in many places (usdview, solaris).

A step further would be to be able to apply arbitrary resolver contexts to proxyShapes.

[kxl-adsk]

@fabal Thanks for bringing this up. I'm catching up on docs around this, it's unclear to me why we need this extra ArGetResolver().CreateDefaultContextForAsset(fileString) . A call to ConfigureResolverForAsset will update the default context. Why do we have to create it again explicitly instead of querying what was already configured?

Regardless, I updated the change to include suggestions raised in this review and matched the code to what is here.

@dolivares-spinvfx please give it a try since you raised this issue originally.

[fabal]

Admittedly, that explicit call to CreateDefaultContextForAsset is not needed in that particular case as Stage::Open does this by default but I guess it could be a good start towards explicit resolver contexts.
Over time, we steered clear of the default resolver context as it can lead to asset resolution "leaks" in complex scenarios (e.g. several proxyShapes, using dedicated resolver context). By "leaks", I don't mean a USD bug, I mean resolution overrides of one asset leaking into another one.
In relation to that, we also ended up guarding most of our calls to Sdf::Layer::FindOrOpen with a resolver context binder.
These comments are mainly for complex asset resolution use cases though, however I believe it is worth mentioning.

[dolivares-spinvfx]

Was just able to test this today due to a disk failure. Seems like asset resolution is working with this change. Thanks!