py-filelock man page
py-filelock — py-filelock Documentation
py-filelock is a single Python module, which implements a platform independent file lock. The lock is thread safe and easy to use:
lock = filelock.FileLock("my_lock_file") with lock: shutil.copy("...", "...")
The lock implements also a counter, which allows you to acquire the lock multiple times without blocking:
lock = filelock.FileLock("my_lock_file") def update_files1(): with lock: assert lock.is_locked # ... return None def update_files2(): with lock: assert lock.is_locked # ... return None def update_all_files(): with lock: assert lock.is_locked update_files1() assert lock.is_locked update_files2() assert lock.is_locked assert not lock.is_locked return None update_all_files()
This package is listed on PyPi, so you’re done with:
$ pip3 install filelock
import filelock lock = filelock.FileLock("my_lock_file") # Simply use the lock into a with statement. with lock: pass # If you want to set a timeout parameter, you can do it by: with lock.acquire(timeout = 10): pass # You can also set a default timeout value, which is used, when no # special timeout value is given to the *acquire()* method: lock.timeout = 20 with lock: # 20s timeout pass with lock.acquire() # 20s timeout pass with lock.acquire(timeout = 10) # 10s timeout pass # If you want to use a timeout value, you should consider to catch # a Timeout exception: try: with lock.acquire(timeout = 10): pass except filelock.Timeout: pass # If you can not use the *with* statement, use a try-finally construct # instead: lock.acquire() try: pass finally: lock.release() # Please note, that you can acquire the lock multiple times without # blocking. The lock will count, how often it has been acquired and releases # the lock, as soon as the counter is 0. with lock: assert lock.is_locked with lock: assert lock.is_locked assert lock.is_locked assert (not lock.is_locked)
A platform independent file lock that supports the with-statement.
- exception filelock.Timeout(lock_file)
Raised when the lock could not be acquired in timeout seconds.
- lock_file = None
The path of the file lock.
- class filelock.BaseFileLock(lock_file, timeout=-1)
Implements the base class of a file lock.
- acquire(timeout=None, poll_intervall=0.05)
Acquires the file lock or fails with a Timeout error.
# You can use this method in the context manager (recommended) with lock.acquire(): pass # Or you use an equal try-finally construct: lock.acquire() try: pass finally: lock.release()
- timeout (float) – The maximum time waited for the file lock. If timeout <= 0, there is no timeout and this method will block until the lock could be acquired. If timeout is None, the default timeout is used.
- poll_intervall (float) – We check once in poll_intervall seconds if we can acquire the file lock.
Timeout – if the lock could not be acquired in timeout seconds.
Changed in version 2.0.0: This method returns now a proxy object instead of self, so that it can be used in a with statement without side effects.
True, if the object holds the file lock.
Changed in version 2.0.0: This was previously a method and is now a property.
The path to the lock file.
Releases the file lock.
Please note, that the lock is only completly released, if the lock counter is 0.
Also note, that the lock file itself is not automatically deleted.
force (bool) – If true, the lock counter is ignored and the lock is released in every case.
You can set a default timeout for the filelock. It will be used as fallback value in the acquire method, if no timeout value (None) is given.
If you want to disable the timeout, set it to a negative value.
A timeout of 0 means, that there is exactly one attempt to acquire the file lock.
New in version 2.0.0.
- class filelock.WindowsFileLock(lock_file, timeout=-1)
Uses the msvcrt.locking() function to hard lock the lock file on windows systems.
- class filelock.UnixFileLock(lock_file, timeout=-1)
Uses the fcntl.flock() to hard lock the lock file on unix systems.
- class filelock.SoftFileLock(lock_file, timeout=-1)
Simply watches the existence of the lock file.
Alias for the lock, which should be used for the current platform. On Windows, this is an alias for WindowsFileLock, on Unix for UnixFileLock and otherwise for SoftFileLock.
alias of UnixFileLock
py-filelock is public domain:
This is free and unencumbered software released into the public domain. Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means. In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. For more information, please refer to <http://unlicense.org>
This module is hosted on GitHub. If you have any questions or suggestions, don’t hesitate to open a new issue :).
2015, Benedikt Schmitt