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############################################
portalocker - Cross-platform locking library
############################################
.. image:: https://travis-ci.org/WoLpH/portalocker.svg?branch=master
:alt: Linux Test Status
:target: https://travis-ci.org/WoLpH/portalocker
.. image:: https://ci.appveyor.com/api/projects/status/mgqry98hgpy4prhh?svg=true
:alt: Windows Tests Status
:target: https://ci.appveyor.com/project/WoLpH/portalocker
.. image:: https://coveralls.io/repos/WoLpH/portalocker/badge.svg?branch=master
:alt: Coverage Status
:target: https://coveralls.io/r/WoLpH/portalocker?branch=master
Overview
--------
Portalocker is a library to provide an easy API to file locking.
An important detail to note is that on Linux and Unix systems the locks are
advisory by default. By specifying the `-o mand` option to the mount command it
is possible to enable mandatory file locking on Linux. This is generally not
recommended however. For more information about the subject:
- https://en.wikipedia.org/wiki/File_locking
- http://stackoverflow.com/questions/39292051/portalocker-does-not-seem-to-lock
- https://stackoverflow.com/questions/12062466/mandatory-file-lock-on-linux
The module is currently maintained by Rick van Hattem <Wolph@wol.ph>.
The project resides at https://github.com/WoLpH/portalocker . Bugs and feature
requests can be submitted there. Patches are also very welcome.
Tips
----
On some networked filesystems it might be needed to force a `os.fsync()` before
closing the file so it's actually written before another client reads the file.
Effectively this comes down to:
::
with portalocker.Lock('some_file', 'rb+', timeout=60) as fh:
# do what you need to do
...
# flush and sync to filesystem
fh.flush()
os.fsync(fh.fileno())
Links
-----
* Documentation
- http://portalocker.readthedocs.org/en/latest/
* Source
- https://github.com/WoLpH/portalocker
* Bug reports
- https://github.com/WoLpH/portalocker/issues
* Package homepage
- https://pypi.python.org/pypi/portalocker
* My blog
- http://w.wol.ph/
Examples
--------
To make sure your cache generation scripts don't race, use the `Lock` class:
>>> import portalocker
>>> with portalocker.Lock('somefile', timeout=1) as fh:
print >>fh, 'writing some stuff to my cache...'
To customize the opening and locking a manual approach is also possible:
>>> import portalocker
>>> file = open('somefile', 'r+')
>>> portalocker.lock(file, portalocker.LOCK_EX)
>>> file.seek(12)
>>> file.write('foo')
>>> file.close()
Explicitly unlocking might not be needed in all cases:
https://github.com/AzureAD/microsoft-authentication-extensions-for-python/issues/42#issuecomment-601108266
But can be done through:
>>> portalocker.unlock(file)
Do note that your data might still be in a buffer so it is possible that your
data is not available until you `flush()` or `close()`.
More examples can be found in the
`tests <http://portalocker.readthedocs.io/en/latest/_modules/tests/tests.html>`_.
Changelog
---------
See the `changelog <http://portalocker.readthedocs.io/en/latest/changelog.html>`_ page.
License
-------
See the `LICENSE <https://github.com/WoLpH/portalocker/blob/develop/LICENSE>`_ file.
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