Welcome to Flockcontext’s documentation!

Contents:

Flockcontext

Improves fcntl.flock usage.

flock is a Unix command for file locking, the mecanism that controls access restrictions of files.

Usage

Exclusive blocking lock:

from flockcontext import FlockOpen

with FlockOpen('/tmp/my.lock', 'w') as lock:
    lock.fd.write('Locked\n')

Exclusive blocking lock with 1 second timeout:

from flockcontext import FlockOpen

with FlockOpen('/tmp/my.lock', 'w', timeout=1) as lock:
    lock.fd.write('Locked\n')

Exclusive non-blocking lock:

from flockcontext import FlockOpen

try:
    with FlockOpen('/tmp/my.lock', 'w', blocking=False) as lock:
        lock.fd.write('Locked\n')
except IOError as e:
    print('Can not acquire lock')

Shared blocking lock:

from flockcontext import Flock

with FlockOpen('/tmp/my.lock', 'w', exclusive=False) as lock:
    lock.fd.write('Locked\n')

Acquire and release within context:

from flockcontext import FlockOpen

with FlockOpen('/tmp/my.lock', 'w') as lock:
    print('Lock acquired')
    lock.fd.write('Locked\n')

    lock.release()
    print('Lock released')

    lock.acquire()
    print('Lock acquired')
    lock.fd.write('Locked\n')

Locking already opened file:

from flockcontext import Flock

with open('/tmp/my.lock', 'w') as fd:
    with Flock(fd):
        fd.write('Locked\n')

License

• Free software: BSD license

Installation

At the command line:

$ pip install flockcontext

Or, if you have virtualenvwrapper installed:

$ mkvirtualenv flockcontext
$ pip install flockcontext

Usage

flockcontext provide two context manager for fcntl.flock. Flock locks an opened file while FlockOpen does the same job but opens the file for you.

FlockOpen exemples

Exclusive blocking lock:: python

from flockcontext import FlockOpen

with FlockOpen(‘/tmp/my.lock’, ‘w’) as lock:

lock.fd.write(‘Lockedn’)

Exclusive non-blocking lock:: python

from flockcontext import FlockOpen

try:

with FlockOpen(‘/tmp/my.lock’, ‘w’, blocking=False) as lock:

lock.fd.write(‘Lockedn’)

except IOError as e:

print(‘Can not acquire lock’)

Shared blocking lock:: python

from flockcontext import Flock

with FlockOpen(‘/tmp/my.lock’, ‘w’, exclusive=False) as lock:

lock.fd.write(‘Lockedn’)

Acquire and release within context:: python

from flockcontext import FlockOpen

with FlockOpen(‘/tmp/my.lock’, ‘w’) as lock:

print(‘Lock acquired’) lock.fd.write(‘Lockedn’)

lock.release() print(‘Lock released’)

lock.acquire() print(‘Lock acquired’) lock.fd.write(‘Lockedn’)

Flock exemples

Blocking lock:: python

from flockcontext import Flock

with open(‘/tmp/my.lock’, ‘w’) as fd:

with Flock(fd):

fd.write(‘Lockedn’)

Non blocking lock:: python

from flockcontext import Flock

with open(‘/tmp/my.lock’, ‘w’) as fd:

try:

with Flock(fd, blocking=False):

fd.write(‘Lockedn’)

except IOError as e:

print(‘Can not acquire lock’)

Shared lock:: python

from flockcontext import Flock

with open(‘/tmp/my.lock’, ‘w’) as fd:

with Flock(fd, exclusive=False):

fd.write(‘Lockedn’)

Acquire and release within context:: python

from flockcontext import Flock

with open(‘/tmp/my.lock’, ‘w’) as fd:

with Flock(fd) as lock:

print(‘Lock acquired’) fd.write(‘Lockedn’)

lock.release() print(‘Lock released’)

lock.acquire() print(‘Lock acquired’) fd.write(‘Lockedn’)

Contributing

Contributions are welcome, and they are greatly appreciated! Every little bit helps, and credit will always be given.

You can contribute in many ways:

Types of Contributions

Report Bugs

Report bugs at https://github.com/AntoineCezar/flockcontext/issues.

If you are reporting a bug, please include:

• Your operating system name and version.
• Any details about your local setup that might be helpful in troubleshooting.
• Detailed steps to reproduce the bug.

Fix Bugs

Look through the GitHub issues for bugs. Anything tagged with “bug” is open to whoever wants to implement it.

Implement Features

Look through the GitHub issues for features. Anything tagged with “feature” is open to whoever wants to implement it.

Write Documentation

Flockcontext could always use more documentation, whether as part of the official Flockcontext docs, in docstrings, or even on the web in blog posts, articles, and such.

Submit Feedback

The best way to send feedback is to file an issue at https://github.com/AntoineCezar/flockcontext/issues.

If you are proposing a feature:

• Explain in detail how it would work.
• Keep the scope as narrow as possible, to make it easier to implement.
• Remember that this is a volunteer-driven project, and that contributions are welcome :)

Get Started!

Ready to contribute? Here’s how to set up flockcontext for local development.

1. Fork the flockcontext repo on GitHub.

2. Clone your fork locally:

   $ git clone git@github.com:your_name_here/flockcontext.git
   

3. Install your local copy into a virtualenv. Assuming you have virtualenvwrapper installed, this is how you set up your fork for local development:

   $ mkvirtualenv flockcontext
   $ cd flockcontext/
   $ make develop
   

4. Create a branch for local development:

   $ git checkout -b name-of-your-bugfix-or-feature
   

   Now you can make your changes locally.

5. When you’re done making changes, check that your changes pass the tests::

   $ make test

6. Check also that they pass the linter::

   $ pip install flake8 $ make lint

7. And that they pass other Python versions (requires https://docs.docker.com/)::

   $ make test-all

8. Commit your changes and push your branch to GitHub:

   $ git add .
   $ git commit -m "Your detailed description of your changes."
   $ git push origin name-of-your-bugfix-or-feature
   

9. Submit a pull request through the GitHub website.

Pull Request Guidelines

Before you submit a pull request, check that it meets these guidelines:

1. The pull request should include tests.
2. If the pull request adds functionality, the docs should be updated. Put your new functionality into a function with a docstring, and add the feature to the list in README.rst.
3. The pull request should work for Python 2.6, 2.7, 3.3, and 3.4, and for PyPy. Check https://travis-ci.org/AntoineCezar/flockcontext/pull_requests and make sure that the tests pass for all supported Python versions.

Credits

Development Lead

• Antoine Cezar <antoine@cezar.fr>

Contributors

• Mathieu Leplatre <contact@mathieu-leplatre.info>

History

0.4.0 (2019-07-03)

• Use docker for mutiple Python version testing from 2.7 to 3.7
• Add proper BSD licence file
• Add timeout for blocking lock
• Upgrade development status to Production/Stable

0.3.1 (2015-08-24)

• Add syntax highlighting for code exemples
• Add Flock manager exemple in README

0.3.0 (2015-08-21)

• Add FlockOpen context manager.

0.2.0 (2015-08-20)

• Add Flock relase and acquire capability withing context.

0.1.0 (2015-08-19)

• Add Flock context manager.

Indices and tables

• Index
• Module Index
• Search Page