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Contents
# frozen_string_literal: true
module Datadog
module Tracing
module Contrib
module Rack
# Retrieves the time spent in an upstream proxy
# for the current Rack request.
#
# This time captures the request delay introduced but
# such proxy before the request made it to the Ruby
# process.
module QueueTime
REQUEST_START = 'HTTP_X_REQUEST_START'
QUEUE_START = 'HTTP_X_QUEUE_START'
MINIMUM_ACCEPTABLE_TIME_VALUE = 1_000_000_000
module_function
def get_request_start(env, now = Time.now.utc)
header = env[REQUEST_START] || env[QUEUE_START]
return unless header
# nginx header is seconds in the format "t=1512379167.574"
# apache header is microseconds in the format "t=1570633834463123"
# heroku header is milliseconds in the format "1570634024294"
time_string = header.to_s.delete('^0-9')
return if time_string.nil?
# Return nil if the time is clearly invalid
time_value = "#{time_string[0, 10]}.#{time_string[10, 6]}".to_f
return if time_value.zero? || time_value < MINIMUM_ACCEPTABLE_TIME_VALUE
# return the request_start only if it's lesser than
# current time, to avoid significant clock skew
request_start = Time.at(time_value)
request_start.utc > now ? nil : request_start
rescue StandardError => e
# in case of an Exception we don't create a
# `request.queuing` span
Datadog.logger.debug("[rack] unable to parse request queue headers: #{e}")
nil
end
end
end
end
end
end
Version data entries
13 entries across 13 versions & 1 rubygems