Best place for metrics module

[donatasm]

I want to write my custom nginx module for measuring request processing time
for every HTTP request received. I need to start counting request processing
time as early as nginx receives first byte of a request and finish, when it
sends the last byte in a response.  What would the best place be in nginx
request processing pipeline to plug in my module and these measuring hooks?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,259040,259040#msg-259040