tools/perf/perf_tools/histogram_measurement.py

   1 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4 from perf_tools import histogram as histogram_module
   5
   6 BROWSER_HISTOGRAM = 'browser_histogram'
   7 RENDERER_HISTOGRAM = 'renderer_histogram'
   8
   9 class HistogramMeasurement(object):
  10   def __init__(self, histogram, histogram_type):
  11     self.name = histogram['name']
  12     self.units = histogram['units']
  13     self.histogram_type = histogram_type
  14     self._start_values = dict()
  15
  16   def Start(self, page, tab):
  17     """Get the starting value for the histogram. This value will then be
  18     subtracted from the actual measurement."""
  19     data = self._GetHistogramFromDomAutomation(tab)
  20     if data:
  21       self._start_values[page.url + self.name] = data
  22
  23   def GetValue(self, page, tab, results):
  24     data = self._GetHistogramFromDomAutomation(tab)
  25     if not data:
  26       return
  27     new_histogram = histogram_module.SubtractHistogram(
  28         data, self._start_values[page.url + self.name])
  29     results.Add(self.name, self.units, new_histogram,
  30                 data_type='unimportant-histogram')
  31
  32   @property
  33   def histogram_function(self):
  34     if self.histogram_type == BROWSER_HISTOGRAM:
  35       return 'getBrowserHistogram'
  36     return 'getHistogram'
  37
  38   def _GetHistogramFromDomAutomation(self, tab):
  39     js = ('window.domAutomationController.%s ? '
  40           'window.domAutomationController.%s("%s") : ""' %
  41           (self.histogram_function, self.histogram_function, self.name))
  42     return tab.EvaluateJavaScript(js)