Question

Is there a Python equivalent to Ruby’s officer gem? It is a distributed locking server, basically allows you to have locks across a network rather than just between threads.

I’ve been looking at elock which has a Python library for it, however elock is unlicensed so we can’t really use it for commercial software (also it has more or less been abandoned).

Ideally the equivalent will fit into twisted, but that’s not necessary.

Answer 1

I ended up solving this by using memcached since it has atomic updates.

The solution is fairly simple:

import memcache

mc = memcache.Client(hosts, debug=1)

# to lock:
def request_lock(key, timeout=300):
    if mc == None:
        raise Exception("Memcache is not connected!")

    # just store a "1" in that location - this is an atomic operation so if two
    # nodes request a lock at the same time, only one of them will get a True
    return mc.add(key, "1", timeout)

# to unlock:
def request_unlock(key):
    if mc == None:
        raise Exception("Memcache is not connected!")

    return mc.delete(key) > 0