tools/metrics/histograms/update_extension_functions.py

   1 # Copyright 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
   5 """Updates ExtensionFunctions enum in histograms.xml file with values read from
   6 extension_function_histogram_value.h.
   7
   8 If the file was pretty-printed, the updated version is pretty-printed too.
   9 """
  10
  11 import logging
  12 import re
  13 import sys
  14
  15 from xml.dom import minidom
  16
  17 from diffutil import PromptUserToAcceptDiff
  18 from pretty_print import PrettyPrintNode
  19
  20 HISTOGRAMS_PATH = 'histograms.xml'
  21 ENUM_NAME = 'ExtensionFunctions'
  22
  23 EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH = \
  24   '../../../chrome/browser/extensions/extension_function_histogram_value.h'
  25 ENUM_START_MARKER = "^enum HistogramValue {"
  26 ENUM_END_MARKER = "^ENUM_BOUNDARY"
  27
  28
  29 class UserError(Exception):
  30   def __init__(self, message):
  31     Exception.__init__(self, message)
  32
  33   @property
  34   def message(self):
  35     return self.args[0]
  36
  37 def ExtractRegexGroup(line, regex):
  38     m = re.match(regex, line)
  39     if m:
  40       return m.group(1)
  41     else:
  42       return None
  43
  44
  45 def ReadHistogramValues(filename):
  46   """Returns a list of pairs (label, value) corresponding to HistogramValue.
  47
  48   Reads the extension_functions_histogram_value.h file, locates the
  49   HistogramValue enum definition and returns a pair for each entry.
  50   """
  51
  52   # Read the file as a list of lines
  53   with open(filename) as f:
  54     content = f.readlines()
  55
  56   # Locate the enum definition and collect all entries in it
  57   inside_enum = False # We haven't found the enum definition yet
  58   result = []
  59   for line in content:
  60     line = line.strip()
  61     if inside_enum:
  62       # Exit condition: we reached last enum value
  63       if re.match(ENUM_END_MARKER, line):
  64         inside_enum = False
  65       else:
  66         # Inside enum: generate new xml entry
  67         label = ExtractRegexGroup(line.strip(), "^([\w]+)")
  68         if label:
  69           result.append((label, enum_value))
  70           enum_value += 1
  71     else:
  72       if re.match(ENUM_START_MARKER, line):
  73         inside_enum = True
  74         enum_value = 0 # Start at 'UNKNOWN'
  75   return result
  76
  77
  78 def UpdateHistogramDefinitions(histogram_values, document):
  79   """Sets the children of <enum name="ExtensionFunctions" ...> node in
  80   |document| to values generated from policy ids contained in
  81   |policy_templates|.
  82
  83   Args:
  84     histogram_values: A list of pairs (label, value) defining each extension
  85                       function
  86     document: A minidom.Document object representing parsed histogram
  87               definitions XML file.
  88
  89   """
  90   # Find ExtensionFunctions enum.
  91   for enum_node in document.getElementsByTagName('enum'):
  92     if enum_node.attributes['name'].value == ENUM_NAME:
  93         extension_functions_enum_node = enum_node
  94         break
  95   else:
  96     raise UserError('No policy enum node found')
  97
  98   # Remove existing values.
  99   while extension_functions_enum_node.hasChildNodes():
 100     extension_functions_enum_node.removeChild(
 101       extension_functions_enum_node.lastChild)
 102
 103   # Add a "Generated from (...)" comment
 104   comment = ' Generated from {0} '.format(
 105     EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
 106   extension_functions_enum_node.appendChild(document.createComment(comment))
 107
 108   # Add values generated from policy templates.
 109   for (label, value) in histogram_values:
 110     node = document.createElement('int')
 111     node.attributes['value'] = str(value)
 112     node.attributes['label'] = label
 113     extension_functions_enum_node.appendChild(node)
 114
 115 def Log(message):
 116   logging.info(message)
 117
 118 def main():
 119   if len(sys.argv) > 1:
 120     print >>sys.stderr, 'No arguments expected!'
 121     sys.stderr.write(__doc__)
 122     sys.exit(1)
 123
 124   Log('Reading histogram enum definition from "%s".'
 125       % (EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH))
 126   histogram_values = ReadHistogramValues(
 127     EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
 128
 129   Log('Reading existing histograms from "%s".' % (HISTOGRAMS_PATH))
 130   with open(HISTOGRAMS_PATH, 'rb') as f:
 131     histograms_doc = minidom.parse(f)
 132     f.seek(0)
 133     xml = f.read()
 134
 135   Log('Comparing histograms enum with new enum definition.')
 136   UpdateHistogramDefinitions(histogram_values, histograms_doc)
 137
 138   Log('Writing out new histograms file.')
 139   new_xml = PrettyPrintNode(histograms_doc)
 140   if PromptUserToAcceptDiff(xml, new_xml, 'Is the updated version acceptable?'):
 141     with open(HISTOGRAMS_PATH, 'wb') as f:
 142       f.write(new_xml)
 143
 144   Log('Done.')
 145
 146
 147 if __name__ == '__main__':
 148   main()