Right, the proposals went beyond that. In this context though I thought
T.J. was looking for a control surface in promises. I shouldn't assume.
In any case, the original challenge here seems solved by something like:
```javascript
var wait = ms => new Promise(resolve => setTimeout(resolve, ms));
async function consumeReadableStream(stream) {
async function read() {
try {
for await (const chunk of stream) {
// do work
}
} catch (e) {
if (e.name != "AbortError") throw e;
}
}
await Promise.race([read(), wait(30000).then(() => stream.destroy())]);
}
```
...assuming .destroy() is overloaded to throw AbortError somehow, a
detail IMHO. But aren't we digressing?
For me, for-await still seems like a useful paradigm, and I'm not sure
readability is helped by using linear code to represent non-linear code
flow.
.: Jan-Ivar :.
On 8/1/17 4:29 PM, Domenic Denicola wrote:
That is not why.
------------------------------------------------------------------------
*From:* Jan-Ivar Bruaroey <[email protected]>
*Sent:* Aug 1, 2017 3:47 PM
*To:* [email protected]
*Subject:* Re: Stream + async await
Because a promise is not a control surface of the asynchronous action
fulfilling it; confuses owner with consumer.
https://stackoverflow.com/a/41417429/918910
.: Jan-Ivar :.
On 7/31/17 7:35 AM, T.J. Crowder wrote:
Related: https://esdiscuss.org/topic/how-about-awaiting-arrays
<https://esdiscuss.org/topic/how-about-awaiting-arrays> (particularly
the discussion of `await.race`), since effectively you're doing a
race between a timeout and each chunk. Also relevant is the former
work on cancelling promises, now withdrawn. (Can anyone point me at
*why* it was withdrawn?)
-- T.J. Crowder
On Mon, Jul 31, 2017 at 6:10 AM, kai zhu <[email protected]
<mailto:[email protected]>> wrote:
the timeout handler will not work as advertised, e.g. what if io
/ db issues causes a network stream to intermittently respond in
intervals far greater than 30000ms or not at all?
> On Jul 31, 2017, at 7:26 AM, James Browning
<[email protected] <mailto:[email protected]>> wrote:
>
> It'll look something like this:
>
> ```javascript
>
> async function consumeReadableStream(stream) {
> const start = Date.now()
> for await (const chunk of stream) {
>
> /* Do whatever you want with the chunk here e,g, await other
> async tasks with chunks
> send them off to wherever, etc
> */
>
> if (Date.now() - start > 30000) {
> throw new Error('30000 ms timeout')
> }
> }
> /* Instead of callbackOnce the returned promise from this
function
> itself can be used */
> }
>
> ```
> _______________________________________________
> es-discuss mailing list
> [email protected] <mailto:[email protected]>
> https://mail.mozilla.org/listinfo/es-discuss
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--
.: Jan-Ivar :.
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