Performance requests

[ronag]

Would be nice if:

• A flag that would cause llhttp to automatically lowercase response headers, so that higher level libraries do not need to perform an additional iteration over headers.

• Parse and include "keep-alive: timeout (\d+)s" in kOnMessageHeadersComplete, e.g. by changing the type of shouldKeepAlive to an integer, so that higher level libraries do not need to perform an additional iteration over headers.

Refs: https://github.com/mcollina/undici/pull/337/files#diff-50cfa59973c04321b5da0c6da0fdf4feR542-R566

[indutny]

I'll investigate, but the second sounds possible. As for the first one, llhttp does not modify the incoming data - it simply isn't possible for it to emit the data that isn't a part of the input. Sorry!

[indutny]

Is keep-alive header a part of this draft https://tools.ietf.org/id/draft-thomson-hybi-http-timeout-01.html ? How widespread is the implementation of it? At glance it looks like it is not part of standard HTTP protocol and that draft has expired...

[ronag]

https://tools.ietf.org/html/draft-thomson-hybi-http-timeout-03#section-2
https://tools.ietf.org/html/rfc7230#appendix-A.1.2

On server side it's supported by nginx and more recently Node. Probably more that I am not aware of. We want to add support for it in the Node core client as well.

It resolves a problem that otherwise cannot be worked around in terms of a connection close race between server and client.

[ronag]

nodejs/node#34561

[ronag]

http://nginx.org/en/docs/http/ngx_http_core_module.html#keepalive_timeout

[indutny]

Excellent! Thank you for sharing the references.

What do you think about the following plan: I'll make this change in a branch and we'll see how much difference it makes for undici. If there is a performance improvement for it - we'll polish the feature and release it, otherwise - we'll call the experiment a failure. Does this sound reasonable?

[ronag]

Sounds great. Thank you for helping out on this.

[indutny]

@ronag could you give a try to this branch please?

[ronag]

Sure. Just need to figure out how to make a node build with it.

[indutny]

Oh, right. Sorry!

I'd clone the repo, checkout the branch, run npm install and make release, and then copy over the contents of release/* into deps/llhttp in Node.js folder.

[ronag]

Hm, I did that, copied to deps/llhttp and overwrote the old files and confirmed they contain the changes. Did a ./configure --ninja and make -j4. However, Node seems to still be running with previous version (i.e. shouldKeepAlive is a boolean)... Any ideas? I'm not too good with the Node build system.

[ronag]

Found it! node_http_parser needs some tuning as well.

[indutny]

You have to patch up node so that it makes it an integer. Let me see what change would do it.