[Installer Test] Update chrome_helper.GetProcessIDAndPathPairs() to use psutil.

chrome/test/mini_installer/chrome_helper.py

 # Copyright 2013 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.
 
 """Common helper module for working with Chrome's processes and windows."""
 
 import ctypes

[grt (UTC plus 2), 2014/09/12 15:01:11]

unused

[huangs, 2014/09/12 18:25:33]

Done.

+import psutil
 import pywintypes

[grt (UTC plus 2), 2014/09/12 15:01:11]

unused

[huangs, 2014/09/12 18:25:33]

Done.

 import re
 import win32con

[grt (UTC plus 2), 2014/09/12 15:01:11]

unused

[huangs, 2014/09/12 18:25:33]

Done.

 import win32gui
 import win32process
 
 
 def GetProcessIDAndPathPairs():
   """Returns a list of 2-tuples of (process id, process path).
-
-  This is needed because psutil is not available on Windows slave machines (see:
-  http://crbug.com/257696).
-  TODO(sukolsak): Use psutil.process_iter() once it becomes available.
   """
   process_id_and_path_pairs = []
-  for process_id in win32process.EnumProcesses():
-    process_handle = ctypes.windll.kernel32.OpenProcess(
-        win32con.PROCESS_QUERY_INFORMATION | win32con.PROCESS_VM_READ, False,
-        process_id)
-    if not process_handle:
-      continue
+  for process in psutil.process_iter():
     try:
-      process_path = win32process.GetModuleFileNameEx(process_handle, 0)
-      process_id_and_path_pairs.append((process_id, process_path))
-    except pywintypes.error:
+      process_id_and_path_pairs.append((process.pid, process.exe))

[grt (UTC plus 2), 2014/09/12 15:01:11]

http://pythonhosted.org/psutil/#psutil.Process says: "When accessing methods of
this class always be prepared to catch NoSuchProcess and AccessDenied
exceptions." Please add another "except" clause to handle NoSuchProcess since
it's possible that the process terminates between the time the iterator returns
the Process instance and the pid/path are retrieved.

[grt (UTC plus 2), 2014/09/12 15:01:11]

process.exe -> process.exe()

[huangs, 2014/09/12 18:25:33]

Catching psutil.Error, per suggested below.

[huangs, 2014/09/12 18:25:33]

From
https://code.google.com/p/psutil/wiki/Documentation
.exe is a string.

I tested the code by printing the return value of GetProcessIDAndPathPairs(),
while 64-bit Chrome was running (also verified that the old code was not
working).

[grt (UTC plus 2), 2014/09/12 18:35:20]

Odd. http://pythonhosted.org/psutil/#psutil.Process.exe says it's a method, as
does https://code.google.com/p/psutil/source/browse/psutil/__init__.py#509

+    except psutil._error.AccessDenied:

[grt (UTC plus 2), 2014/09/12 15:01:11]

perhaps just catch psutil.Error here, since that's the base for NoSuchProcess
and AccessDenied.

[huangs, 2014/09/12 18:25:33]

Done.

       # It's normal that some processes are not accessible.
       pass
   return process_id_and_path_pairs
 
 
 def GetProcessIDs(process_path):
   """Returns a list of IDs of processes whose path is |process_path|.
 
   Args:
     process_path: The path to the process.
 
   Returns:
     A list of process IDs.
   """
   return [pid for (pid, path) in GetProcessIDAndPathPairs() if
           path == process_path]
 
 
 def GetWindowHandles(process_ids):

[grt (UTC plus 2), 2014/09/12 15:01:11]

this looks unnecessarily racy for the case where it's called by
quit_chrome.py:CloseWindows(). i think it would be better if CloseWindows()
ended up doing something more like this (possibly indirectly via helper
functions in a pythonic way):
  for each hwnd,pid pair found by EnumWindows (dynamically, not caching all
pairs and then looping over them):
    process = psutil.Process(pid)
    if process.exe() == process_path and process.is_running():
      post WM_CLOSE to the hwnd
it may make sense to cache the Process instances (mapped by pid) while doing the
window iteration since each proc may have many, many hwnds. reset the item in
the cache if is_running() ever returns false, since that will mean the pid has
potentially been reused.

swing by to chat if this doesn't seem to make any sense. :-)

[huangs, 2014/09/12 18:25:33]

EnumWindow() only looks at top-level windows, so there won't be 10,000 entries;
more like in the order of 100.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms633497(v=vs.85).aspx

Ideally we should use "yield".  Problem is win32gui.EnumWindows() does not allow
this.  Solving this would lead to overengineering, so per discussion, keeping
the array way...  :(

   """Returns a list of handles of windows owned by processes in |process_ids|.
 
   Args:
     process_ids: A list of process IDs.
 
   Returns:
     A list of handles of windows owned by processes in |process_ids|.
   """
   hwnds = []
   def EnumerateWindowCallback(hwnd, _):
@@ skipping 16 matching lines @@
     process_ids: A list of process IDs.
     class_pattern: The regular expression pattern of the window class name.
 
   Returns:
     A boolean indicating whether such window exists.
   """
   for hwnd in GetWindowHandles(process_ids):
     if re.match(class_pattern, win32gui.GetClassName(hwnd)):
       return True
   return False