[esp-nghttp]: ability to tune NGHTTP2_INBOUND_BUFFER_LENGTH (IEC-325)

[bryghtlabs-richard]

Is your feature request related to a problem?

I don't have internal space for more threads, and there's plenty of buffering at TCP & TLS layers for my application already.

Describe the solution you'd like.

I'd like the ability to adjust NGHTTP2_INBOUND_BUFFER_LENGTH through sdkconfig. 16KB is a lot to ask of many embedded devices.

Describe alternatives you've considered.

No response

Additional context.

No response

[mahavirj]

I briefly checked on this, feature will need changes to upstream nghttp2 library. I think changes may go beyond nghttp2/nghttp2#2470, as I can see few more places where there is assumption about max inbound buffer length. Probably working with upstream maintainers will help.

Once the buffer size is configurable in upstream library version, we can update the component on our side.

[bryghtlabs-richard]

Probably working with upstream maintainers will help.

Is there anything else I should do besides the pull request?

I think changes may go beyond nghttp2/nghttp2#2470, as I can see few more places where there is assumption about max inbound buffer length.

I double-checked our fork and upstream but I only saw it used in nghttp2_session_recv(). I believe all the uses of said buffer involve involve sizeof(buf). We've been using that patch for a couple months now in production.

[mahavirj]

@bryghtlabs-richard

I took a deeper look and it appears that your proposed change should be good enough. Earlier, I was skeptical about NGHTTP2_MAX_PAYLOADLEN but that controls maximum frame payload size. Please send a reminder to your upstream PR and let's hope that it gets merged.

[bryghtlabs-richard]

I pinged them. Perhaps a mention by someone from Espressif might help too?