URL_response timing metrics explanation

Issue/Introduction:

How the timing metrics are captured and computed by url_response probe?

Environment:

Release:
Component: UIMURL

Resolution:

-- QOS_URL_RESPONSE
Normally QOS_URL_RESPONSE is CURLINFO_TOTAL_TIME but in case ignore connection time is enabled CURLINFO_TOTAL_TIME is the difference between CURLINFO_TOTAL_TIME and CURLINFO_CONNECT_TIME

-- QOS_URL_DNSRESOLVE_TIME
QOS_URL_DNSRESOLVE_TIME is CURLINFO_NAMELOOKUP_TIME.

-- QOS_URL_DOWNLOAD_TIME
QOS_URL_DOWNLOAD_TIME is the difference between CURLINFO_TOTAL_TIME and CURLINFO_STARTTRANSFER_TIME

-- QOS_URL_TCPCONNECT_TIME
QOS_URL_TCPCONNECT_TIME is the difference between CURLINFO_CONNECT_TIME and CURLINFO_NAMELOOKUP_TIME

-- QOS_URL_FIRSTBYTE_TIME
QOS_URL_FIRSTBYTE_TIME is the difference between CURLINFO_STARTTRANSFER_TIME and CURLINFO_CONNECT_TIME

-- QOS_URL_LASTBYTE_TIME
QOS_URL_LASTBYTE_TIME is the difference between CURLINFO_TOTAL_TIME and CURLINFO_CONNECT_TIME

-- QOS_URL_REDIRECT_TIME
QOS_URL_REDIRECT_TIME is CURLINFO_REDIRECT_TIME

The CURL APIs provides data in second as a unit of time, multiply it with 1000 to provide QOS data in ms.

Additional Information:

CURLINFO_TOTAL_TIME
https://curl.haxx.se/libcurl/c/CURLINFO_TOTAL_TIME.html

CURLINFO_STARTTRANSFER_TIME
https://curl.haxx.se/libcurl/c/CURLINFO_STARTTRANSFER_TIME.html

CURLINFO_CONNECT_TIME
https://curl.haxx.se/libcurl/c/CURLINFO_CONNECT_TIME.html

CURLINFO_NAMELOOKUP_TIME
https://curl.haxx.se/libcurl/c/CURLINFO_NAMELOOKUP_TIME.html

CURLINFO_REDIRECT_TIME
https://curl.haxx.se/libcurl/c/CURLINFO_REDIRECT_TIME.html

Commands to run the CURL variables:

https://blog.cloudflare.com/a-question-of-timing/

https://netbeez.net/blog/http-transaction-timing-breakdown-with-curl/