#

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.