https://github.com/SPSCommerce/redlock-py

Redis distributed locks in Python
https://github.com/SPSCommerce/redlock-py

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Redis distributed locks in Python

• Host: GitHub
• URL: https://github.com/SPSCommerce/redlock-py
• Owner: SPSCommerce
• License: mit
• Archived: true
• Created: 2014-09-29T19:45:24.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2020-12-11T12:17:01.000Z (almost 4 years ago)
• Last Synced: 2024-07-16T14:09:38.141Z (4 months ago)
• Language: Python
• Size: 28.3 KB
• Stars: 571
• Watchers: 33
• Forks: 118
• Open Issues: 12
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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redlock-py - Redis distributed locks in Python

This python lib implements the Redis-based distributed lock manager algorithm [described in this blog post](http://redis.io/topics/distlock).

To create a lock manager:

    dlm = Redlock([{"host": "localhost", "port": 6379, "db": 0}, ])

To acquire a lock:

    my_lock = dlm.lock("my_resource_name",1000)

Where the resource name is an unique identifier of what you are trying to lock

and 1000 is the number of milliseconds for the validity time.

The returned value is `False` if the lock was not acquired (you may try again),

otherwise an namedtuple representing the lock is returned, having three fields:

* validity, an integer representing the number of milliseconds the lock will be valid.

* resource, the name of the locked resource as specified by the user.

* key, a random value which is used to safe reclaim the lock.

To release a lock:

    dlm.unlock(my_lock)

It is possible to setup the number of retries (by default 3) and the retry

delay (by default 200 milliseconds) used to acquire the lock.

Both `dlm.lock` and `dlm.unlock` raise a exception `MultipleRedlockException` if there are errors when communicating with one or more redis masters. The caller of `dlm` should

use a try-catch-finally block to handle this exception. A `MultipleRedlockException` object

encapsulates multiple `redis-py.exceptions.RedisError` objects.

**Disclaimer**: This code implements an algorithm which is currently a proposal, it was not formally analyzed. Make sure to understand how it works before using it in your production environments.

Further Reading:

http://redis.io/topics/distlock

http://martin.kleppmann.com/2016/02/08/how-to-do-distributed-locking.html

http://antirez.com/news/101

https://medium.com/@talentdeficit/redlock-unsafe-at-any-time-40ceac109dbb#.uj9ffh96x