question: order of stream handlers
dvic opened this issue · comments
I noticed that when compress is set to true, the order of the stream handlers is: [:cowboy_compress_h | @default_stream_handlers], where @default_stream_handlers is [:cowboy_telemetry_h, :cowboy_stream_h].
Does this work as I understand it in that the telemetry does not take into account the compression handler? Is this working as intended or should the compression be taken into account? I can imagine this is a breaking change but we could put it behind a flag or support compress: [metrics: true] or something like that.
Good catch. I think we can simply have two sets of default handlers, one for compressed and another for non compressed. Would that work?
yes for me it would :) and then just keep the current compress: boolean() as an option? i’m not sure if this is considered a breaking change (as the metric meaning will change)
The only metric meaning that will change is that will measure more, right?! If so, that’s ok. /cc @binaryseed
The only metric meaning that will change is that will measure more, right?! If so, that’s ok. /cc @binaryseed
correct
The way cowboy_telemetry works is by wrapping cowboy_metrics_h. The metrics stream handler marks its ending measurement in the terminate cowboy stream handler callback. Since cowboy_compress_h does all its compression work in the data stream handler callback, I believe that the compression time is already included in the overall duration reported.
Thanks @binaryseed !
That clears it up, thanks!