Telemetry: Adds a Windows PGO profiler.

tools/telemetry/telemetry/core/platform/profiler/win_pgo_profiler.py

Index: tools/telemetry/telemetry/core/platform/profiler/win_pgo_profiler.py
diff --git a/tools/telemetry/telemetry/core/platform/profiler/win_pgo_profiler.py b/tools/telemetry/telemetry/core/platform/profiler/win_pgo_profiler.py
new file mode 100644
index 0000000000000000000000000000000000000000..693191504723dc48a4aeec6fcad9a11633bd2a1a
--- /dev/null
+++ b/tools/telemetry/telemetry/core/platform/profiler/win_pgo_profiler.py
@@ -0,0 +1,102 @@
+# Copyright 2014 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 glob
+import os
+import subprocess
+import sys
+
+from telemetry.core.platform import profiler
+
+
+_PGOSWEEP_EXECUTABLE = 'pgosweep.exe'
+
+
+class WinPGOProfiler(profiler.Profiler):
+  """A profiler that run the Visual Studio PGO utility 'pgosweep.exe' before
+  terminating a browser or a renderer process.
+  """
+
+  def __init__(self, browser_backend, platform_backend, output_path, state):
+    super(WinPGOProfiler, self).__init__(
+        browser_backend, platform_backend, output_path, state)
+
+    pgosweep_is_in_path = False

[tonyg, 2014/05/17 08:49:42]

Just curious whether support_binaries.FindSupportBinary('pgosweep') works here.
We might also consider uploading it to internal cloud storage.
http://www.chromium.org/developers/telemetry/upload_to_cloud_storage

[Sébastien Marchand, 2014/05/21 15:15:27]

It seems that FindSupportBinary looks for the binaries in the source tree,
pgosweep.exe is a part of the toolchain (it comes with cl.exe, link.exe etc...).
This is already in our internal cloud storage as a part of the win toolchain
(checked in depot_tools).

Also FindSupportBinary doesn't seem to be present in my checkout (part of a
Chromium checkout), is this normal ? (It's also not on code search:
https://code.google.com/p/chromium/codesearch#chromium/src/tools/telemetry/te...)

+    for entry in os.environ['PATH'].split(os.pathsep):
+      if os.path.exists(os.path.join(entry, _PGOSWEEP_EXECUTABLE)):
+        pgosweep_is_in_path = True
+        break
+    if not pgosweep_is_in_path:
+      raise IOError(2, '%s isn\'t in the current path, run vcvarsall.bat to fix'
+           ' this.' % _PGOSWEEP_EXECUTABLE)
+
+    self._browser_dir = browser_backend.browser_directory
+    self._chrome_pgc_counter = self._GetNextProfileIndex('chrome')
+    self._chrome_child_pgc_counter = self._GetNextProfileIndex('chrome_child')
+
+  def _GetNextProfileIndex(self, dll_name):
+    """Scan the directory containing the DLL |dll_name| to find the next index
+    to use for the profile data files.
+
+    Args:
+      dll_name: The name of the DLL for which we want to get the next index to
+          to use.
+    """
+    max_index = 0
+    pgc_files = glob.glob(os.path.join(self._browser_dir,
+                                       '%s!*.pgc' % dll_name))
+    for pgc_file in pgc_files:
+      max(max_index,
+          int(os.path.splitext(os.path.split(pgc_file)[1])[0].split('!')[1]))
+    return max_index + 1
+
+  def _RunPGOSweep(self, pid, dll_name, index):
+    """Run the pgosweep utility to gather the profile data of a given process.
+
+    Args:
+      pid: The PID of the process we're interested in.
+      dll_name: The name of the DLL for which we want the profile data.
+      index: The index to use for the profile data file.
+
+    Returns the name of the profile data file.
+    """
+    pgc_filename = '%s\\%s!%d.pgc' % (self._browser_dir, dll_name, index)
+    subprocess.Popen([_PGOSWEEP_EXECUTABLE,
+                      '/pid:%d' % pid,
+                      '%s.dll' % dll_name,
+                      pgc_filename]
+                    ).wait()
+    return pgc_filename
+
+  @classmethod
+  def name(cls):
+    return 'win_pgo_profiler'
+
+  @classmethod
+  def is_supported(cls, browser_type):
+    # This profiler only make sense when doing a Windows build with Visual
+    # Studio (minimal supported version is 2013 Update 2).
+    return sys.platform.startswith('win')
+
+  @classmethod
+  def CustomizeBrowserOptions(cls, browser_type, options):
+    # The sandbox need to be disabled if we want to be able to gather the
+    # profile data.

[tonyg, 2014/05/17 08:49:42]

No action necessary, but I do just idly wonder how much this hurts the quality
of the profile.

[Sébastien Marchand, 2014/05/21 15:15:27]

This might have alter the data a little bit (e.g. we won't optimize the
sandbox...) but we don't really have a choice here :(

+    options.AppendExtraBrowserArgs('--no-sandbox')
+
+  def CollectProfile(self):
+    """Collect the profile data for the current processes."""
+    output_files = []
+    for pid, output_file in self._GetProcessOutputFileMap().iteritems():
+      if 'renderer' in output_file:
+        output_files.append(self._RunPGOSweep(pid,
+                                              'chrome_child',
+                                              self._chrome_child_pgc_counter))
+        self._chrome_child_pgc_counter += 1
+      elif 'browser0' in output_file:
+        output_files.append(self._RunPGOSweep(pid,
+                                              'chrome',
+                                              self._chrome_pgc_counter))
+        self._chrome_pgc_counter += 1
+    return output_files