fix: Client.stream writableNeedDrain

[ronag]

Fixes: #441
Refs: nodejs/node#35348
Refs: nodejs/node#35341

[ronag]

Missing tests. WIP

[ronag]

@mcollina: PTAL

[ronag]

@indutny @addaleax I'm working around the fact that I can't pause the parser in a callback. Do you have any better suggestions on how to go about that?

[mcollina]

I don't understand this fix. Why is this needed at all?

(A slightly better implementation would go and replace the kOn* methods when paused to avoid the ifs on an hot path).

[ronag]

I don't understand this fix. Why is this needed at all?

Because currently when pausing we don't actually pause and the parser might invoke more callbacks. It's more of a hint.

A slightly better implementation would go and replace the kOn* methods when paused to avoid the ifs on an hot path

I think this is negligable.

[ronag]

I guess it's not entirely necessary... though the current implementation isn't strictly correct. The docs would need to be updated to reflect that returning false from onBody is only a hint.

[mcollina]

Have you benchmarked this?

[ronag]

Yes, difference is within margin of error (which is quite large, we should probably increase number of samples in benchmark again).

[ronag]

I've cleaned this up a bit and also added more assertions to make it clearer what this fixes.

[mcollina]

LGTM