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

[Victor Stinner]

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."""

Victor