[Flight] Include env in ReactAsyncInfo and ReactIOInfo #33400
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eps1lon
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This lets us keep track of which environment this was fetched and awaited. Currently the IO and await is in the same environment. Once we support forwarding information from a Promise fetched from another environment, the await can end up being in a different environment.
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…#33402) Stacked on #33400. <img width="1261" alt="Screenshot 2025-06-01 at 10 27 47 PM" src="https://github.com/user-attachments/assets/a5a73ee2-49e0-4851-84ac-e0df6032efb5" /> This is emitted with the start/end time and stack of the "await". Which may be different than the thing that started the I/O. These awaits aren't quite as simple as just every await since you can start a sequence in parallel there can actually be multiple overlapping awaits and there can be CPU work interleaved with the await on the same component. ```js function getData() { await fetch(...); await fetch(...); } const promise = getData(); doWork(); await promise; ``` This has two "I/O" awaits but those are actually happening in parallel with `doWork()`. Since these also could have started before we started rendering this sequence (e.g. a component) we have to clamp it so that we don't consider awaits that start before the component. What we're conceptually trying to convey is the time this component was blocked due to that I/O resource. Whether it's blocked from completing the last result or if it's blocked from issuing a waterfall request.
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Stacked on #33395.
This lets us keep track of which environment this was fetched and awaited.
Currently the IO and await is in the same environment. It's just kept when forwarded. Once we support forwarding information from a Promise fetched from another environment and awaited in this environment then the await can end up being in a different environment.
There's a question of when the await is inside Flight itself such as when you return a promise fetched from another environment whether that should mean that the await is in the current environment. I don't think so since the original stack trace is the best stack trace. It's only if you
awaitit in user space in this environment first that this might happen and even then it should only be considered if there wasn't a better await earlier or if reading from the other environment was itself I/O.The timing of when we read
environmentName()is a little interesting here too.