rsnext/test/e2e/cancel-request/sleep.ts
Justin Ridgewell 31d2b720d9
Reimplement stream cancellation (#52281)
### What?

This reimplements our stream cancellation code for a few more cases:
1. Adds support in all stream-returning APIs
2. Fixes cancellation detection in node 16
3. Implements out-of-band detection, so can cancel in the middle of a
read

It also (finally) adds tests for all the cases I'm aware of.

### Why?

To allow disconnecting from an AI service when a client disconnects. $$$

### How?

1. Reuses a single pipe function in all paths to push data from the
dev's `ReadableStream` into our `ServerResponse`
2. Uses `ServerResponse` to detect disconnect, instead of the
`IncomingMessage` (request)
    - The `close` event fire once all incoming body data is read
- The request `abort` event will not fire after the incoming body data
has been fully read
3. Using `on('close')` on the writable destination allows us to detect
close
- Checking for `res.destroyed` in the body of the loop meant we had to
wait for the `await stream.read()` to complete before we could possibly
cancel the stream

- - -

#52157 (and #51594) had an issue with Node 16, because I was using
`res.closed` to detect when the server response was closed by the client
disconnecting. But, `closed` wasn't
[added](https://github.com/nodejs/node/pull/45672) until
[v18.13.0](https://nodejs.org/en/blog/release/v18.13.0#:~:text=%5Bcbd710bbf4%5D%20%2D%20http%3A%20make%20OutgoingMessage%20more%20streamlike%20(Robert%20Nagy)%20%2345672).
This fixes it by using `res.destroyed`.

Reverts #52277
Relands #52157
Fixes #52809

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2023-07-26 12:57:34 -07:00

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TypeScript

export function sleep(ms: number) {
return new Promise((res) => setTimeout(res, ms))
}
export class Deferred<T> {
declare promise: Promise<T>
declare resolve: (v?: T | PromiseLike<T>) => void
declare reject: (r?: any) => void
constructor() {
this.promise = new Promise((res, rej) => {
this.resolve = res
this.reject = rej
})
}
}