module NewRelic::Agent::Instrumentation::QueueTime
docs.newrelic.com/docs/features/tracking-front-end-time Record queue time metrics based on any of three headers which can be set on the request.
Constants
- CANDIDATE_HEADERS
- DIVISORS
- EARLIEST_ACCEPTABLE_TIME
-
any timestamps before this are thrown out and the parser will try again with a larger unit (2000/1/1 UTC)
- MIDDLEWARE_START_HEADER
- QUEUE_START_HEADER
- REQUEST_START_HEADER
Public Instance Methods
Source
# File lib/new_relic/agent/instrumentation/queue_time.rb, line 29 def parse_frontend_timestamp(headers, now = Process.clock_gettime(Process::CLOCK_REALTIME)) earliest = nil CANDIDATE_HEADERS.each do |header| if headers[header] parsed = parse_timestamp(timestamp_string_from_header_value(headers[header])) if parsed && (!earliest || parsed < earliest) earliest = parsed end end end if earliest && earliest > now NewRelic::Agent.logger.debug("Negative queue time detected, treating as zero: start=#{earliest.to_f} > now=#{now}") earliest = now end earliest end
Source
# File lib/new_relic/agent/instrumentation/queue_time.rb, line 58 def parse_timestamp(string) DIVISORS.each do |divisor| begin t = (string.to_f / divisor) return t if t > EARLIEST_ACCEPTABLE_TIME rescue RangeError # On Ruby versions built with a 32-bit time_t, attempting to # instantiate a Time object in the far future raises a RangeError, # in which case we know we've chosen the wrong divisor. end end nil end
Source
# File lib/new_relic/agent/instrumentation/queue_time.rb, line 49 def timestamp_string_from_header_value(value) case value when /^\s*([\d+\.]+)\s*$/ then $1 # following regexp intentionally unanchored to handle # (ie ignore) leading server names when /t=([\d+\.]+)/ then $1 end end