Telemetry: Create new profile creator large_profile_creator.

tools/perf/profile_creators/history_profile_extender.py

+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+import multiprocessing
+import tempfile
+import os
+
+from profile_creators import fast_navigation_profile_extender
+
+
+class HistoryProfileExtender(
+    fast_navigation_profile_extender.FastNavigationProfileExtender):
+  """This extender navigates Chrome to a large number of URIs pointing to local
+  files. It continues running until the history DB becomes full."""
+  _HISTORY_DB_MAX_SIZE_IN_MB = 10
+
+  def __init__(self):
+    # The rate limiting factors are the speed of page navigation, and the speed
+    # of python bindings. The former is larger than the latter, so having a
+    # large batch size skews the amortized average time per page load towards
+    # the latter.
+    maximum_batch_size = multiprocessing.cpu_count() * 2
+    super(HistoryProfileExtender, self).__init__(maximum_batch_size)
+
+    # A list of paths of temporary files. The instance is responsible for
+    # making sure that the files are deleted before they are removed from this
+    # list.
+    self._generated_temp_files = []
+
+  def _MakeTemporaryFile(self):
+    """Makes a temporary file and returns a URI to the file.
+
+    This method has the side effect of appending the temporary file to
+    self._generated_temp_files. The instance is responsible for deleting the
+    file at a later point in time.
+    """
+    # Adding a long suffix to the name of the file fills up the history
+    # database faster. The suffix can't be too long, since some file systems
+    # have a 256 character limit on the length of the path. While we could
+    # dynamically vary the length of the path, that would generate different
+    # profiles on different OSes, which is not ideal.
+    suffix = "reallylongsuffixintendedtoartificiallyincreasethelengthoftheurl"
+
+    # Neither tempfile.TemporaryFile() nor tempfile.NamedTemporaryFile() work
+    # well here. The former doesn't work at all, since it doesn't gaurantee a
+    # file-system visible path. The latter doesn't work well, since the
+    # returned file cannot be opened a second time on Windows. The returned
+    # file would have to be closed, and the method would need to be called with
+    # Delete=False, which makes its functionality no simpler than
+    # tempfile.mkstemp().
+    handle, path = tempfile.mkstemp(suffix=suffix)
+    os.close(handle)
+    self._generated_temp_files.append(path)
+
+    file_url = "file://" + path
+    return file_url
+
+  def GetUrlIterator(self):
+    """Superclass override."""
+    while True:
+      yield self._MakeTemporaryFile()
+
+  def ShouldExitAfterBatchNavigation(self):
+    """Superclass override."""
+    return self._IsHistoryDBAtMaxSize()
+
+  def TearDown(self):
+    """Superclass override."""
+    super(HistoryProfileExtender, self).TearDown()
+    for path in self._generated_temp_files:
+      os.remove(path)
+    self._generated_temp_files = []
+
+  def CleanUpAfterBatchNavigation(self):
+    """Superclass override."""
+    for path in self._generated_temp_files:
+      os.remove(path)
+    self._generated_temp_files = []
+
+  def _IsHistoryDBAtMaxSize(self):
+    """Whether the history DB has reached its maximum size."""
+    history_db_path = os.path.join(self.profile_path, "Default", "History")
+    stat_info = os.stat(history_db_path)
+    size = stat_info.st_size
+
+    max_size_threshold = 0.95
+    bytes_in_megabyte = 2**10
+    max_size = (bytes_in_megabyte *
+        HistoryProfileExtender._HISTORY_DB_MAX_SIZE_IN_MB * max_size_threshold)
+    return size > max_size