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238 lines
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238 lines
9.3 KiB
Plaintext
Metadata-Version: 2.1
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Name: scandir
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Version: 1.10.0
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Summary: scandir, a better directory iterator and faster os.walk()
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Home-page: https://github.com/benhoyt/scandir
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Author: Ben Hoyt
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Author-email: benhoyt@gmail.com
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License: New BSD License
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Platform: UNKNOWN
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Classifier: Development Status :: 5 - Production/Stable
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Classifier: Intended Audience :: Developers
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Classifier: Operating System :: OS Independent
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Classifier: License :: OSI Approved :: BSD License
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Classifier: Programming Language :: Python
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Classifier: Topic :: System :: Filesystems
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Classifier: Topic :: System :: Operating System
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Classifier: Programming Language :: Python
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Classifier: Programming Language :: Python :: 2
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Classifier: Programming Language :: Python :: 2.7
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Classifier: Programming Language :: Python :: 3
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Classifier: Programming Language :: Python :: 3.4
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Classifier: Programming Language :: Python :: 3.5
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Classifier: Programming Language :: Python :: 3.6
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Classifier: Programming Language :: Python :: 3.7
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Classifier: Programming Language :: Python :: Implementation :: CPython
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scandir, a better directory iterator and faster os.walk()
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=========================================================
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.. image:: https://img.shields.io/pypi/v/scandir.svg
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:target: https://pypi.python.org/pypi/scandir
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:alt: scandir on PyPI (Python Package Index)
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.. image:: https://travis-ci.org/benhoyt/scandir.svg?branch=master
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:target: https://travis-ci.org/benhoyt/scandir
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:alt: Travis CI tests (Linux)
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.. image:: https://ci.appveyor.com/api/projects/status/github/benhoyt/scandir?branch=master&svg=true
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:target: https://ci.appveyor.com/project/benhoyt/scandir
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:alt: Appveyor tests (Windows)
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``scandir()`` is a directory iteration function like ``os.listdir()``,
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except that instead of returning a list of bare filenames, it yields
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``DirEntry`` objects that include file type and stat information along
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with the name. Using ``scandir()`` increases the speed of ``os.walk()``
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by 2-20 times (depending on the platform and file system) by avoiding
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unnecessary calls to ``os.stat()`` in most cases.
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Now included in a Python near you!
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----------------------------------
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``scandir`` has been included in the Python 3.5 standard library as
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``os.scandir()``, and the related performance improvements to
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``os.walk()`` have also been included. So if you're lucky enough to be
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using Python 3.5 (release date September 13, 2015) you get the benefit
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immediately, otherwise just
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`download this module from PyPI <https://pypi.python.org/pypi/scandir>`_,
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install it with ``pip install scandir``, and then do something like
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this in your code:
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.. code-block:: python
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# Use the built-in version of scandir/walk if possible, otherwise
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# use the scandir module version
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try:
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from os import scandir, walk
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except ImportError:
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from scandir import scandir, walk
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`PEP 471 <https://www.python.org/dev/peps/pep-0471/>`_, which is the
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PEP that proposes including ``scandir`` in the Python standard library,
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was `accepted <https://mail.python.org/pipermail/python-dev/2014-July/135561.html>`_
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in July 2014 by Victor Stinner, the BDFL-delegate for the PEP.
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This ``scandir`` module is intended to work on Python 2.7+ and Python
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3.4+ (and it has been tested on those versions).
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Background
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----------
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Python's built-in ``os.walk()`` is significantly slower than it needs to be,
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because -- in addition to calling ``listdir()`` on each directory -- it calls
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``stat()`` on each file to determine whether the filename is a directory or not.
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But both ``FindFirstFile`` / ``FindNextFile`` on Windows and ``readdir`` on Linux/OS
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X already tell you whether the files returned are directories or not, so
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no further ``stat`` system calls are needed. In short, you can reduce the number
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of system calls from about 2N to N, where N is the total number of files and
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directories in the tree.
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In practice, removing all those extra system calls makes ``os.walk()`` about
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**7-50 times as fast on Windows, and about 3-10 times as fast on Linux and Mac OS
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X.** So we're not talking about micro-optimizations. See more benchmarks
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in the "Benchmarks" section below.
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Somewhat relatedly, many people have also asked for a version of
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``os.listdir()`` that yields filenames as it iterates instead of returning them
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as one big list. This improves memory efficiency for iterating very large
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directories.
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So as well as a faster ``walk()``, scandir adds a new ``scandir()`` function.
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They're pretty easy to use, but see "The API" below for the full docs.
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Benchmarks
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----------
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Below are results showing how many times as fast ``scandir.walk()`` is than
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``os.walk()`` on various systems, found by running ``benchmark.py`` with no
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arguments:
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==================== ============== =============
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System version Python version Times as fast
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==================== ============== =============
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Windows 7 64-bit 2.7.7 64-bit 10.4
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Windows 7 64-bit SSD 2.7.7 64-bit 10.3
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Windows 7 64-bit NFS 2.7.6 64-bit 36.8
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Windows 7 64-bit SSD 3.4.1 64-bit 9.9
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Windows 7 64-bit SSD 3.5.0 64-bit 9.5
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Ubuntu 14.04 64-bit 2.7.6 64-bit 5.8
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Mac OS X 10.9.3 2.7.5 64-bit 3.8
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==================== ============== =============
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All of the above tests were done using the fast C version of scandir
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(source code in ``_scandir.c``).
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Note that the gains are less than the above on smaller directories and greater
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on larger directories. This is why ``benchmark.py`` creates a test directory
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tree with a standardized size.
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The API
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-------
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walk()
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~~~~~~
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The API for ``scandir.walk()`` is exactly the same as ``os.walk()``, so just
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`read the Python docs <https://docs.python.org/3.5/library/os.html#os.walk>`_.
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scandir()
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~~~~~~~~~
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The full docs for ``scandir()`` and the ``DirEntry`` objects it yields are
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available in the `Python documentation here <https://docs.python.org/3.5/library/os.html#os.scandir>`_.
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But below is a brief summary as well.
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scandir(path='.') -> iterator of DirEntry objects for given path
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Like ``listdir``, ``scandir`` calls the operating system's directory
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iteration system calls to get the names of the files in the given
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``path``, but it's different from ``listdir`` in two ways:
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* Instead of returning bare filename strings, it returns lightweight
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``DirEntry`` objects that hold the filename string and provide
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simple methods that allow access to the additional data the
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operating system may have returned.
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* It returns a generator instead of a list, so that ``scandir`` acts
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as a true iterator instead of returning the full list immediately.
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``scandir()`` yields a ``DirEntry`` object for each file and
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sub-directory in ``path``. Just like ``listdir``, the ``'.'``
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and ``'..'`` pseudo-directories are skipped, and the entries are
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yielded in system-dependent order. Each ``DirEntry`` object has the
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following attributes and methods:
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* ``name``: the entry's filename, relative to the scandir ``path``
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argument (corresponds to the return values of ``os.listdir``)
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* ``path``: the entry's full path name (not necessarily an absolute
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path) -- the equivalent of ``os.path.join(scandir_path, entry.name)``
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* ``is_dir(*, follow_symlinks=True)``: similar to
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``pathlib.Path.is_dir()``, but the return value is cached on the
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``DirEntry`` object; doesn't require a system call in most cases;
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don't follow symbolic links if ``follow_symlinks`` is False
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* ``is_file(*, follow_symlinks=True)``: similar to
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``pathlib.Path.is_file()``, but the return value is cached on the
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``DirEntry`` object; doesn't require a system call in most cases;
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don't follow symbolic links if ``follow_symlinks`` is False
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* ``is_symlink()``: similar to ``pathlib.Path.is_symlink()``, but the
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return value is cached on the ``DirEntry`` object; doesn't require a
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system call in most cases
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* ``stat(*, follow_symlinks=True)``: like ``os.stat()``, but the
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return value is cached on the ``DirEntry`` object; does not require a
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system call on Windows (except for symlinks); don't follow symbolic links
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(like ``os.lstat()``) if ``follow_symlinks`` is False
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* ``inode()``: return the inode number of the entry; the return value
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is cached on the ``DirEntry`` object
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Here's a very simple example of ``scandir()`` showing use of the
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``DirEntry.name`` attribute and the ``DirEntry.is_dir()`` method:
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.. code-block:: python
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def subdirs(path):
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"""Yield directory names not starting with '.' under given path."""
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for entry in os.scandir(path):
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if not entry.name.startswith('.') and entry.is_dir():
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yield entry.name
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This ``subdirs()`` function will be significantly faster with scandir
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than ``os.listdir()`` and ``os.path.isdir()`` on both Windows and POSIX
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systems, especially on medium-sized or large directories.
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Further reading
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---------------
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* `The Python docs for scandir <https://docs.python.org/3.5/library/os.html#os.scandir>`_
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* `PEP 471 <https://www.python.org/dev/peps/pep-0471/>`_, the
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(now-accepted) Python Enhancement Proposal that proposed adding
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``scandir`` to the standard library -- a lot of details here,
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including rejected ideas and previous discussion
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Flames, comments, bug reports
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-----------------------------
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Please send flames, comments, and questions about scandir to Ben Hoyt:
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http://benhoyt.com/
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File bug reports for the version in the Python 3.5 standard library
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`here <https://docs.python.org/3.5/bugs.html>`_, or file bug reports
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or feature requests for this module at the GitHub project page:
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https://github.com/benhoyt/scandir
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