Class: StackifyRubyAPM::ResponseManipulator

Inherits:
Object
  • Object
show all
Defined in:
lib/stackify_apm/response_manipulator.rb

Overview

an abstraction for manipulating the HTML we capture in the middleware

Constant Summary collapse

SCAN_LIMIT =

examine in order to look for a RUM insertion point.

50_000
HEAD_START = 
'<head'.freeze
HEAD_END = 
'</head'.freeze
RUM_SCRIPT_VARIABLE = 
'[RUM_SCRIPT_VARIABLE'.freeze
BRKT = 
']'.freeze
GT = 
'>'.freeze
CHARSET_RE = 
/<\s*meta[^>]+charset\s*=[^>]*>/
X_UA_COMPATIBLE_RE = 
/<\s*meta[^>]+http-equiv\s*=\s*['"]x-ua-compatible['"][^>]*>/

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(env, rack_response, config) ⇒ ResponseManipulator

Returns a new instance of ResponseManipulator.



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# File 'lib/stackify_apm/response_manipulator.rb', line 24

def initialize(env, rack_response, config)
  @env = env
  @rack_response = rack_response

  @rack_status = rack_response[0]
  @rack_headers = rack_response[1]
  @rack_body = rack_response[2]
  @rack_flagger = nil
  @config = config
end

Instance Attribute Details

#env ⇒ Object (readonly)

Returns the value of attribute env.



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# File 'lib/stackify_apm/response_manipulator.rb', line 12

def env
  @env
end

#jsfile_to_inject ⇒ Object (readonly)

Returns the value of attribute jsfile_to_inject.



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# File 'lib/stackify_apm/response_manipulator.rb', line 10

def jsfile_to_inject
  @jsfile_to_inject
end

#rack_body ⇒ Object (readonly)

Returns the value of attribute rack_body.



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# File 'lib/stackify_apm/response_manipulator.rb', line 11

def rack_body
  @rack_body
end

#Rack_flagger ⇒ Object (readonly)

Returns the value of attribute Rack_flagger.



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# File 'lib/stackify_apm/response_manipulator.rb', line 11

def Rack_flagger
  @Rack_flagger
end

#rack_headers ⇒ Object (readonly)

Returns the value of attribute rack_headers.



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# File 'lib/stackify_apm/response_manipulator.rb', line 11

def rack_headers
  @rack_headers
end

#rack_response ⇒ Object (readonly)

Returns the value of attribute rack_response.



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# File 'lib/stackify_apm/response_manipulator.rb', line 10

def rack_response
  @rack_response
end

#rack_status ⇒ Object (readonly)

Returns the value of attribute rack_status.



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# File 'lib/stackify_apm/response_manipulator.rb', line 11

def rack_status
  @rack_status
end

Instance Method Details

#adjust_pagehtml_response(rum_variable_script = false) ⇒ Object

rubocop:disable Metrics/CyclomaticComplexity rubocop:disable Metrics/PerceivedComplexity



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# File 'lib/stackify_apm/response_manipulator.rb', line 59

def adjust_pagehtml_response(rum_variable_script = false)
  response = @rack_body
  source = gather_source(response)
  close_old_response(response)
  return nil unless source

  client_id = @config.client_id
  device_id = @config.device_id
  client_rundomain = @config.client_run_domain
  inject_flag = false

  if client_rundomain != '' && StackifyRubyAPM.check_isdomain(client_rundomain) && client_id && device_id
    inject_flag = true
  else
    warn 'ClientRumDomain might be empty or Invalid URL stackify.properties.'
  end

  return unless inject_flag
  jsfile_to_inject = StackifyRubyAPM.inject_rum_script

  # Only scan the first 50k (roughly) then give up.
  beginning_of_source = source[0..SCAN_LIMIT]

  meta_tag_positions = [
    find_x_ua_compatible_position(beginning_of_source),
    find_charset_position(beginning_of_source)
  ].compact

  insertion_index = if !meta_tag_positions.empty?
                      meta_tag_positions.max
                    else
                      find_end_of_head_open(beginning_of_source)
                    end

  if insertion_index && inject_flag
    source = source[0...insertion_index] <<
             jsfile_to_inject <<
             source[insertion_index..-1]
    source = source.gsub('[RUM_SCRIPT_VARIABLE]', '') if rum_variable_script
  end
  source
end

#call_manipulate ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 35

def call_manipulate
  if check_rumscript_variable
    adjust_pagehtml_response(true)
  else
    adjust_pagehtml_response
  end
end

#check_rumscript_variable ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 43

def check_rumscript_variable
  response = @rack_body
  source = gather_source(response)
  close_old_response(response)
  return false unless source

  return true if source.include?(RUM_SCRIPT_VARIABLE)
  false
end

#close_old_response(response) ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 130

def close_old_response(response)
  response.close if response.respond_to?(:close)
end

#find_charset_position(beginning_of_source) ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 119

def find_charset_position(beginning_of_source)
  match = CHARSET_RE.match(beginning_of_source)
  match.end(0) if match
end

#find_end_of_head_open(beginning_of_source) ⇒ Object

rubocop:enable Metrics/CyclomaticComplexity rubocop:enable Metrics/PerceivedComplexity



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# File 'lib/stackify_apm/response_manipulator.rb', line 104

def find_end_of_head_open(beginning_of_source)
  head_open = beginning_of_source.index(HEAD_END)
  beginning_of_source.index(GT, head_open) - 6 if head_open
end

#find_rum_script_variable_index(beginning_of_source) ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 109

def find_rum_script_variable_index(beginning_of_source)
  head_open = beginning_of_source.index(RUM_SCRIPT_VARIABLE)
  beginning_of_source.index(BRKT, head_open) - 20 if head_open
end

#find_x_ua_compatible_position(beginning_of_source) ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 114

def find_x_ua_compatible_position(beginning_of_source)
  match = X_UA_COMPATIBLE_RE.match(beginning_of_source)
  match.end(0) if match
end

#gather_source(response) ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 124

def gather_source(response)
  source = nil
  response.each { |fragment| source ? (source << fragment.to_s) : (source = fragment.to_s) }
  source
end

#rebuild_rack_response ⇒ Object 



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# File 'lib/stackify_apm/response_manipulator.rb', line 53

def rebuild_rack_response
  [rack_status, rack_headers, rack_body]
end