zc.lockfile 1.1.0

Detailed Documentation

Lock file support

The ZODB lock_file module provides support for creating file system locks. These are locks that are implemented with lock files and OS-provided locking facilities. To create a lock, instantiate a LockFile object with a file name:

>>> import zc.lockfile
>>> lock = zc.lockfile.LockFile('lock')

If we try to lock the same name, we’ll get a lock error:

>>> import zope.testing.loggingsupport
>>> handler = zope.testing.loggingsupport.InstalledHandler('zc.lockfile')
>>> try:
...     zc.lockfile.LockFile('lock')
... except zc.lockfile.LockError:
...     print("Can't lock file")
Can't lock file

>>> for record in handler.records: # doctest: +ELLIPSIS
...     print(record.levelname+' '+record.getMessage())
ERROR Error locking file lock; pid=...

To release the lock, use it’s close method:

>>> lock.close()

The lock file is not removed. It is left behind:

>>> import os
>>> os.path.exists('lock')
True

Of course, now that we’ve released the lock, we can create it again:

>>> lock = zc.lockfile.LockFile('lock')
>>> lock.close()

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