Measuring Response time based on POST and GET Parameters

using the following code, i was able to get the response time based on POST and GET Parameters, however i am still getting some TCL Error in logs

 

 

TCL error: Response_Time_2 - Illegal argument (line 9) invoked from within "HTTP::collect [HTTP::header Content-Length]" ("POST" arm line 3) invoked from within "switch [HTTP::method] { "GET"

 

 

when HTTP_REQUEST {
  
set http_request_time [clock clicks -milliseconds]
set theurl [HTTP::uri]
set theip [IP::client_addr]
set wmethod [HTTP::method]
set contype [HTTP::header Content-Type]
set POSTQuery ""
set GETQuery ""

  switch [HTTP::method] {
    "GET" {
       Inspect Query String
     
      set GETQuery [string tolower [URI::query "?&[HTTP::query]" hidActionName]]
    }
    "POST" {
      if { [HTTP::header Content-Type] eq "application/x-www-form-urlencoded" } {
        HTTP::collect [HTTP::header Content-Length]
      }
    }
  }
}

when HTTP_REQUEST_DATA {

set POSTQuery [string tolower [URI::query "?[HTTP::payload]" hidActionName]]
  }


when HTTP_RESPONSE {

set http_response_time [ clock clicks -milliseconds ]
log 10.0.10.16:514 local0. "CEF:0|XX|XX|10.2|200|Response Time|2|src=$theip request=$theurl cn1=[expr $http_response_time - $http_request_time] cs1=$wmethod cs2=$contype cs4=$POSTQuery cs6=$GETQuery"

}