Description:
We want to record timestamps in a Lua filter so that we know when requests and responses occur (and eventually derive the duration).
It appears Lua doesn't have a function to do this - os.time provides current time, but only at seconds, not millis or ns. os.clock provides a timestamp, but only for time spent in Lua.

Maybe something like request_handle:timestamp?

Relevant Links:
https://stackoverflow.com/questions/463101/lua-current-time-in-milliseconds