Initial draft of AsyncLocalStorage interoperable subset

[jasnell]

No description provided.

[littledan]

This document looks great! I just have a couple suggestions for clarity inline.

It'd be good if this document had an introduction explaining its rationale for existing, its relationship to AsyncContext, and how we hope that this will be a transitional subset rather than the recommended API forever.

[Qard]

I think AsyncResource is a bit of a code smell with how much of it is not actually relevant to AsyncLocalStorage. Can we add AsyncLocalStorage.bind(...) as a wrapper for the Node.js use of it to abstract away those additional irrelevant bits? The way this is written now closely matches how Node.js works currently but I think it should be fine to deviate a bit for the sake of a cleaner interface to share between runtimes.

[jasnell]

@Qard:

Can we add AsyncLocalStorage.bind(...) as a wrapper for the Node.js use of it to abstract away those additional irrelevant bits?

Let's separate this conversation. I have some concerns about the feasibility of per-AsyncLocalStorage propagation rules given the O(n) complexity that introduces.

[Qard]

Per-storage binding we can put aside, but I think a global bind would be suitable as a direct equivalent to AsyncResource, and matches what AsyncContext proposed with its wrap function.

[jasnell]

@Qard :

Per-storage binding we can put aside, but I think a global bind would be suitable as a direct equivalent to AsyncResource, and matches what AsyncContext proposed with its wrap function.

Let's take discussion about adding an AsyncLocalStore.bind(...) to a Node.js issue or PR. I'm in favor if the semantics are really just an alias for AsyncResource.bind(...) but I think there are a few other details to consider before we can replace AsyncResource and it's just better to discuss those details over there.

[jasnell]

Given that I think we have reasonable agreement on the basic API itself, I'm going to go ahead and merge this and we can continue to tweak as necessary with individual PRs