Class: Rack::SpeedTracer::Context

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/speedtracer/context.rb

Constant Summary collapse

TRACER_PATH = 
/^\/speedtracer/.freeze
CONTENT_TYPE = 
'application/json;charset=UTF-8'.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}, &blk) ⇒ Context

Returns a new instance of Context.



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# File 'lib/rack/speedtracer/context.rb', line 10

def initialize(app, options = {}, &blk)
  @app  = app
  @uuid = UUID.new

  # TODO: storage strategy...
  # initialize_options with options
  # yield self if block_given?

  @db = {}
end

Instance Attribute Details

#db ⇒ Object

Returns the value of attribute db.



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# File 'lib/rack/speedtracer/context.rb', line 8

def db
  @db
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/rack/speedtracer/context.rb', line 21

def call(env)
  if env['PATH_INFO'].match(TRACER_PATH)

    resp = Rack::Response.new('', 200)
    resp['Content-Type'] = CONTENT_TYPE

    case env['REQUEST_METHOD']
      when 'HEAD' then
        # SpeedTracer dispatches HEAD requests to verify the
        # tracer endpoint when it detects the X-TraceUrl
        # header for the first time. After the initial load
        # the verification is cached by the extension.
        #
        # By default, we'll return 200.

      when 'GET' then
        # GET requests for specific trace are generated by
        # the extension when the user expands the network
        # resource tab. Hence, server-side tracer data is
        # request on-demand, and we need to store it for
        # some time.

        qs = Rack::Utils.parse_query(env['QUERY_STRING'])
        if qs['id'] && @db[qs['id']]
          resp.write @db[qs['id']]
        else
          # Invalid request or missing request trace id
          resp.status = 404
        end
      else
        # SpeedTracer should only issue GET & HEAD requests
        resp.status = 400
    end

    return resp.finish
  end

  env['st.id']   = @uuid.generate
  env['st.tracer'] = Tracer.new(env['st.id'], env['REQUEST_METHOD'], env['REQUEST_URI'])

  @status, @headers, @response = @app.call(env)
  @db[env['st.id']] = env['st.tracer'].finish

  # set the TraceUrl header to notify SpeedTracer that
  # serverside meta-data is available for this request
  @headers['X-TraceUrl'] = '/speedtracer?id=' + env['st.id']

  [@status, @headers, @response]
end