[v9.x] stream: always reset awaitDrain when emitting data

[addaleax]

Backport of #18516, only conflict being the added debug() line that is being borrowed from 1e0f331

[addaleax]

CI: https://ci.nodejs.org/job/node-test-commit/16420/

[addaleax]

New CI: https://ci.nodejs.org/job/node-test-pull-request/13376/

Could I get an approval on this?

[MylesBorins]

@addaleax looks like this could use a rebase and another CI run

[addaleax]

@nodejs/streams I’m not sure why this test is failing, but it seems like it’s more complex and has to do with different timing between 9.x and master?

The failure looks like this:

Mismatched <anonymous> function calls. Expected exactly 3, actual 2.
    at Object.exports.mustCall (/home/sqrt/src/node/v9/test/common/index.js:437:10)
    at Object.<anonymous> (/home/sqrt/src/node/v9/test/parallel/test-stream-pipe-await-drain-push-while-write.js:17:17)
    at Module._compile (module.js:662:30)
    at Object.Module._extensions..js (module.js:673:10)
    at Module.load (module.js:575:32)
    at tryModuleLoad (module.js:515:12)
    at Function.Module._load (module.js:507:3)
    at Function.Module.runMain (module.js:703:10)
    at startup (bootstrap_node.js:193:16)

[mcollina]

'readable' is always deferred in master, that can explain it.

[MylesBorins]

@mcollina next steps for this PR?

[addaleax]

I’m not sure how to fix the issues I was getting here – and it does seem like this is still a valid and necessary bug fix, the test fails without the changes to the streams code on v9.x.

[mcollina]

I will need to have a look. The fix for v9.x (and 8.x) might be more complicated. This is probably leveraging #18515 (which is semver-major).

[mcollina]

I do not think this is backportable to 9 or 8.
The stream is left in a paused state with this change, as it relies on .push() deferring any activity to the next tick, which is semver major (#18515).

I think we can close this and flag #18516 as dont-land-on-9. It might be possible to do a completely different fix for the issue on 8 or 9, but I don't see this severe enough to be worth the effort (but happy to reconsider if there is a specific need).

[addaleax]

Ok, I’ll close this then. Thanks for investigating! And I agree, if somebody runs into this issue we can still look into it in more details.