tools/perf/profile_creators/history_profile_extender.py

   1 # Copyright 2015 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 import multiprocessing
   5 import os
   6 import tempfile
   7
   8 from profile_creators import fast_navigation_profile_extender
   9
  10
  11 class HistoryProfileExtender(
  12     fast_navigation_profile_extender.FastNavigationProfileExtender):
  13   """This extender navigates Chrome to a large number of URIs pointing to local
  14   files. It continues running until the history DB becomes full."""
  15   _HISTORY_DB_MAX_SIZE_IN_MB = 10
  16
  17   def __init__(self, finder_options):
  18     # The rate limiting factors are the speed of page navigation, and the speed
  19     # of python bindings. The former is larger than the latter, so having a
  20     # large batch size skews the amortized average time per page load towards
  21     # the latter.
  22     maximum_batch_size = multiprocessing.cpu_count() * 2
  23     super(HistoryProfileExtender, self).__init__(
  24         finder_options, maximum_batch_size)
  25
  26     # A list of paths of temporary files. The instance is responsible for
  27     # making sure that the files are deleted before they are removed from this
  28     # list.
  29     self._generated_temp_files = []
  30
  31   def _MakeTemporaryFile(self):
  32     """Makes a temporary file and returns a URI to the file.
  33
  34     This method has the side effect of appending the temporary file to
  35     self._generated_temp_files. The instance is responsible for deleting the
  36     file at a later point in time.
  37     """
  38     # Adding a long suffix to the name of the file fills up the history
  39     # database faster. The suffix can't be too long, since some file systems
  40     # have a 256 character limit on the length of the path. While we could
  41     # dynamically vary the length of the path, that would generate different
  42     # profiles on different OSes, which is not ideal.
  43     suffix = "reallylongsuffixintendedtoartificiallyincreasethelengthoftheurl"
  44
  45     # Neither tempfile.TemporaryFile() nor tempfile.NamedTemporaryFile() work
  46     # well here. The former doesn't work at all, since it doesn't gaurantee a
  47     # file-system visible path. The latter doesn't work well, since the
  48     # returned file cannot be opened a second time on Windows. The returned
  49     # file would have to be closed, and the method would need to be called with
  50     # Delete=False, which makes its functionality no simpler than
  51     # tempfile.mkstemp().
  52     handle, path = tempfile.mkstemp(suffix=suffix)
  53     os.close(handle)
  54     self._generated_temp_files.append(path)
  55
  56     file_url = "file://" + path
  57     return file_url
  58
  59   def GetUrlIterator(self):
  60     """Superclass override."""
  61     while True:
  62       yield self._MakeTemporaryFile()
  63
  64   def ShouldExitAfterBatchNavigation(self):
  65     """Superclass override."""
  66     return self._IsHistoryDBAtMaxSize()
  67
  68   def TearDownBrowser(self):
  69     """Superclass override."""
  70     super(HistoryProfileExtender, self).TearDownBrowser()
  71     for path in self._generated_temp_files:
  72       os.remove(path)
  73     self._generated_temp_files = []
  74
  75   def CleanUpAfterBatchNavigation(self):
  76     """Superclass override."""
  77     for path in self._generated_temp_files:
  78       os.remove(path)
  79     self._generated_temp_files = []
  80
  81   def _IsHistoryDBAtMaxSize(self):
  82     """Whether the history DB has reached its maximum size."""
  83     history_db_path = os.path.join(self.profile_path, "Default", "History")
  84     stat_info = os.stat(history_db_path)
  85     size = stat_info.st_size
  86
  87     max_size_threshold = 0.95
  88     bytes_in_megabyte = 2**20
  89     max_size = (bytes_in_megabyte *
  90         HistoryProfileExtender._HISTORY_DB_MAX_SIZE_IN_MB * max_size_threshold)
  91     return size > max_size