[Engineering] [varnishkafka] RFC switch to VUT API for varnish 5.2+ support

Fri Apr 13 14:23:55 UTC 2018

Hello,

I am sorry if this is not the correct mailing list to discuss this.

At Camptocamp we are using varnishkafka, and we are looking to upgrade
to varnish 5.2, however since Varnish broke the VSM API we will need to
change varnishkafka too.

Since they decided to make VUT API public, I was thinking of switching
varnishkafka to it. Hopefully this API will be more stable than VSM API.

This would basically transform the whole while block into a single call
to VUT_Main() with a slightly modified dispatch function and some call
to VUT_Init/VUT_Setup correct params
(https://github.com/wikimedia/varnishkafka/blob/master/varnishkafka.c#L2150-L2195).

The only blocking point I can see, is the call to rd_kafka_poll which
will need to be made somehow outside of the "main" thread since VUT_Main
is a main loop (a periodic call via timer/thread with a while and
blocking call?).

I have only analyzed the possibility but not started coding. I prefer to
have some input first, what do you think of this proposal?

Best regards,

Diego Abelenda