stream: ensure finish is emitted in next tick

[ronag]

When using end() it was possible for 'finish' to be emitted synchronously causing incorrect behaviour and subtle bugs.

This is an edge case not usually encountered since a write() is usually pending and will be the one to initiate finishMaybe() through afterWrite which is always async.

This PR also cause _destroy() to be called in nextTick when autoDestroy is enabled during this edge case.

NOTE: 'prefinish' must be synchronous in order to not break Transform. I've got another PR in the works to sort this out.

Should probably be semver major.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[ronag]

@Trott: Who's familiar with net? When thinking about this I just realized that I'm not sure whether net ensures that it won't call _undestroy before 'close' (which I believe is a required invariant regardless of this PR, this PR might make it worse though if this is not the case). I wasn't able to determine this.

[Trott]

@Trott: Who's familiar with net?

Good question. I'm surprised there isn't a @nodejs/net team. Using git blame to identify the most recent author of lines in lib/net.js that call _undestroy(), that person is @mcollina so let's start with them.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/27252/

[lpinca]

CITGM: https://ci.nodejs.org/view/Node.js-citgm/job/citgm-smoker/2100/

[ronag]

@benjamingr can I get a nodejs/streams ping on this one?

[ronag]

net has a synchronous _destroy so _undestroy should be somewhat safe where it's called. See, #30832.

[benjamingr]

@nodejs/streams also this is terrifying :D

[addaleax]

This needs another @nodejs/tsc approval (@mcollina?) but should otherwise be good to go

[mcollina]

lgtm

[ronag]

@Trott: I think this needs a CITGM and then might be able to land? If CITGM is ok I think this can land?

[Trott]

CITGM looks good.

[Trott]

Landed in e13a37e