[Python-Dev] cpython (3.2): Fix #11583. Changed os.path.isdir to use GetFileAttributes instead of os.stat.

[Brian Curtin]

On Thu, Jun 9, 2011 at 04:05, Victor Stinner
<victor.stinner at haypocalc.com>wrote:

> Le jeudi 09 juin 2011 à 08:16 +0200, Georg Brandl a écrit :
> > On 06/09/11 02:00, brian.curtin wrote:
> > > http://hg.python.org/cpython/rev/88e318166eaf
> > > changeset:   70713:88e318166eaf
> > > branch:      3.2
> > > parent:      70700:0aa3064d1cef
> > > user:        Brian Curtin <brian at python.org>
> > > date:        Wed Jun 08 18:17:18 2011 -0500
> > > summary:
> > >   Fix #11583. Changed os.path.isdir to use GetFileAttributes instead of
> os.stat.
> > >
> > > By changing to the Windows GetFileAttributes API in nt._isdir we can
> figure
> > > out if the path is a directory without opening the file via os.stat.
> This has
> > > the minor benefit of speeding up os.path.isdir by at least 2x for
> regular
> > > files and 10-15x improvements were seen on symbolic links (which opened
> the
> > > file multiple times during os.stat). Since os.path.isdir is used in
> > > several places on interpreter startup, we get a minor speedup in
> startup time.
> > >
> > > files:
> > >   Lib/ntpath.py         |  13 ++++++++++
> > >   Misc/NEWS             |   3 ++
> > >   Modules/posixmodule.c |  37 +++++++++++++++++++++++++++++++
> > >   3 files changed, 53 insertions(+), 0 deletions(-)
> > >
> > >
> > > diff --git a/Lib/ntpath.py b/Lib/ntpath.py
> > > --- a/Lib/ntpath.py
> > > +++ b/Lib/ntpath.py
> > > @@ -672,3 +672,16 @@
> > >  def sameopenfile(f1, f2):
> > >      """Test whether two file objects reference the same file"""
> > >      return _getfileinformation(f1) == _getfileinformation(f2)
> > > +
> > > +
> > > +try:
> > > +    # The genericpath.isdir implementation uses os.stat and checks the
> mode
> > > +    # attribute to tell whether or not the path is a directory.
> > > +    # This is overkill on Windows - just pass the path to
> GetFileAttributes
> > > +    # and check the attribute from there.
> > > +    from nt import _isdir
> > > +except ImportError:
> > > +    from genericpath import isdir as _isdir
> > > +
> > > +def isdir(path):
> > > +    return _isdir(path)
> >
> > Not that it matters, but ISTM that this would be faster as
> >
> > try:
> >     from nt import _isdir as isdir
> > except ImportError:
> >     pass
>
> I would matter if _isdir() had a docstring, but it doesn't :-)
> genericpath.isdir() has the following doc:
>
> def isdir(s):
>    """Return true if the pathname refers to an existing directory."""


http://hg.python.org/lookup/d40609dd01e0 adds the docstring back in and
redoes the imports as Georg mentioned, which is better.
Thanks for having a look.
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