media/PRESUBMIT.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 """Top-level presubmit script for Chromium media component.
   6
   7 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
   8 for more details about the presubmit API built into depot_tools.
   9 """
  10
  11 def _FilterFile(affected_file):
  12   """Return true if the file could contain code requiring a presubmit check."""
  13   return affected_file.LocalPath().endswith(
  14       ('.h', '.cc', '.cpp', '.cxx', '.mm'))
  15
  16
  17 def _CheckForUseOfWrongClock(input_api, output_api):
  18   """Make sure new lines of media code don't use a clock susceptible to skew."""
  19
  20   # Regular expression that should detect any explicit references to the
  21   # base::Time type (or base::Clock/DefaultClock), whether in using decls,
  22   # typedefs, or to call static methods.
  23   base_time_type_pattern = r'(^|\W)base::(Time|Clock|DefaultClock)(\W|$)'
  24
  25   # Regular expression that should detect references to the base::Time class
  26   # members, such as a call to base::Time::Now.
  27   base_time_member_pattern = r'(^|\W)(Time|Clock|DefaultClock)::'
  28
  29   # Regular expression to detect "using base::Time" declarations.  We want to
  30   # prevent these from triggerring a warning.  For example, it's perfectly
  31   # reasonable for code to be written like this:
  32   #
  33   #   using base::Time;
  34   #   ...
  35   #   int64 foo_us = foo_s * Time::kMicrosecondsPerSecond;
  36   using_base_time_decl_pattern = r'^\s*using\s+(::)?base::Time\s*;'
  37
  38   # Regular expression to detect references to the kXXX constants in the
  39   # base::Time class.  We want to prevent these from triggerring a warning.
  40   base_time_konstant_pattern = r'(^|\W)Time::k\w+'
  41
  42   problem_re = input_api.re.compile(
  43       r'(' + base_time_type_pattern + r')|(' + base_time_member_pattern + r')')
  44   exception_re = input_api.re.compile(
  45       r'(' + using_base_time_decl_pattern + r')|(' +
  46       base_time_konstant_pattern + r')')
  47   problems = []
  48   for f in input_api.AffectedSourceFiles(_FilterFile):
  49     for line_number, line in f.ChangedContents():
  50       if problem_re.search(line):
  51         if not exception_re.search(line):
  52           problems.append(
  53               '  %s:%d\n    %s' % (f.LocalPath(), line_number, line.strip()))
  54
  55   if problems:
  56     return [output_api.PresubmitPromptOrNotify(
  57         'You added one or more references to the base::Time class and/or one\n'
  58         'of its member functions (or base::Clock/DefaultClock). In media\n'
  59         'code, it is rarely correct to use a clock susceptible to time skew!\n'
  60         'Instead, could you use base::TimeTicks to track the passage of\n'
  61         'real-world time?\n\n' +
  62         '\n'.join(problems))]
  63   else:
  64     return []
  65
  66
  67 def _CheckForMessageLoopProxy(input_api, output_api):
  68   """Make sure media code only uses MessageLoopProxy for accessing the current
  69   loop."""
  70
  71   message_loop_proxy_re = input_api.re.compile(
  72       r'\bMessageLoopProxy(?!::current\(\))')
  73
  74   problems = []
  75   for f in input_api.AffectedSourceFiles(_FilterFile):
  76     for line_number, line in f.ChangedContents():
  77       if message_loop_proxy_re.search(line):
  78         problems.append('%s:%d' % (f.LocalPath(), line_number))
  79
  80   if problems:
  81     return [output_api.PresubmitError(
  82       'MessageLoopProxy should only be used for accessing the current loop.\n'
  83       'Use the TaskRunner interfaces instead as they are more explicit about\n'
  84       'the run-time characteristics. In most cases, SingleThreadTaskRunner\n'
  85       'is a drop-in replacement for MessageLoopProxy.', problems)]
  86
  87   return []
  88
  89
  90 def _CheckForHistogramOffByOne(input_api, output_api):
  91   """Make sure histogram enum maxes are used properly"""
  92
  93   # A general-purpose chunk of regex to match whitespace and/or comments
  94   # that may be interspersed with the code we're interested in:
  95   comment = r'/\*.*?\*/|//[^\n]*'
  96   whitespace = r'(?:[\n\t ]|(?:' + comment + r'))*'
  97
  98   # The name is assumed to be a literal string.
  99   histogram_name = r'"[^"]*"'
 100
 101   # This can be an arbitrary expression, so just ensure it isn't a ; to prevent
 102   # matching past the end of this statement.
 103   histogram_value = r'[^;]*'
 104
 105   # In parens so we can retrieve it for further checks.
 106   histogram_max = r'([^;,]*)'
 107
 108   # This should match a uma histogram enumeration macro expression.
 109   uma_macro_re = input_api.re.compile(
 110       r'\bUMA_HISTOGRAM_ENUMERATION\(' + whitespace + histogram_name + r',' +
 111       whitespace + histogram_value + r',' + whitespace + histogram_max +
 112       whitespace + r'\)' + whitespace + r';(?:' + whitespace +
 113       r'\/\/ (PRESUBMIT_IGNORE_UMA_MAX))?')
 114
 115   uma_max_re = input_api.re.compile(r'.*(?:Max|MAX).* \+ 1')
 116
 117   problems = []
 118
 119   for f in input_api.AffectedSourceFiles(_FilterFile):
 120     contents = input_api.ReadFile(f)
 121
 122     # We want to match across lines, but still report a line number, so we keep
 123     # track of the line we're on as we search through the file.
 124     line_number = 1
 125
 126     # We search the entire file, then check if any violations are in the changed
 127     # areas, this is inefficient, but simple. A UMA_HISTOGRAM_ENUMERATION call
 128     # will often span multiple lines, so finding a match looking just at the
 129     # deltas line-by-line won't catch problems.
 130     match = uma_macro_re.search(contents)
 131     while match:
 132       line_number += contents.count('\n', 0, match.start())
 133       max_arg = match.group(1) # The third argument.
 134
 135       if (not uma_max_re.match(max_arg) and match.group(2) !=
 136           'PRESUBMIT_IGNORE_UMA_MAX'):
 137         uma_range = range(match.start(), match.end() + 1)
 138         # Check if any part of the match is in the changed lines:
 139         for num, line in f.ChangedContents():
 140           if line_number <= num <= line_number + match.group().count('\n'):
 141             problems.append('%s:%d' % (f, line_number))
 142             break
 143
 144       # Strip off the file contents up to the end of the match and update the
 145       # line number.
 146       contents = contents[match.end():]
 147       line_number += match.group().count('\n')
 148       match = uma_macro_re.search(contents)
 149
 150   if problems:
 151     return [output_api.PresubmitError(
 152       'UMA_HISTOGRAM_ENUMERATION reports in src/media/ are expected to adhere\n'
 153       'to the following guidelines:\n'
 154       ' - The max value (3rd argument) should be an enum value equal to the\n'
 155       '   last valid value, e.g. FOO_MAX = LAST_VALID_FOO.\n'
 156       ' - 1 must be added to that max value.\n'
 157       'Contact rileya@chromium.org if you have questions.' , problems)]
 158
 159   return []
 160
 161
 162 def _CheckChange(input_api, output_api):
 163   results = []
 164   results.extend(_CheckForUseOfWrongClock(input_api, output_api))
 165   results.extend(_CheckForMessageLoopProxy(input_api, output_api))
 166   results.extend(_CheckForHistogramOffByOne(input_api, output_api))
 167   return results
 168
 169
 170 def CheckChangeOnUpload(input_api, output_api):
 171   return _CheckChange(input_api, output_api)
 172
 173
 174 def CheckChangeOnCommit(input_api, output_api):
 175   return _CheckChange(input_api, output_api)