You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
81 lines
2.2 KiB
81 lines
2.2 KiB
"""ZooKeeper Leader Elections
|
|
|
|
:Maintainer: None
|
|
:Status: Unknown
|
|
|
|
"""
|
|
from kazoo.exceptions import CancelledError
|
|
|
|
|
|
class Election(object):
|
|
"""Kazoo Basic Leader Election
|
|
|
|
Example usage with a :class:`~kazoo.client.KazooClient` instance::
|
|
|
|
zk = KazooClient()
|
|
zk.start()
|
|
election = zk.Election("/electionpath", "my-identifier")
|
|
|
|
# blocks until the election is won, then calls
|
|
# my_leader_function()
|
|
election.run(my_leader_function)
|
|
|
|
"""
|
|
|
|
def __init__(self, client, path, identifier=None):
|
|
"""Create a Kazoo Leader Election
|
|
|
|
:param client: A :class:`~kazoo.client.KazooClient` instance.
|
|
:param path: The election path to use.
|
|
:param identifier: Name to use for this lock contender. This
|
|
can be useful for querying to see who the
|
|
current lock contenders are.
|
|
|
|
"""
|
|
self.lock = client.Lock(path, identifier)
|
|
|
|
def run(self, func, *args, **kwargs):
|
|
"""Contend for the leadership
|
|
|
|
This call will block until either this contender is cancelled
|
|
or this contender wins the election and the provided leadership
|
|
function subsequently returns or fails.
|
|
|
|
:param func: A function to be called if/when the election is
|
|
won.
|
|
:param args: Arguments to leadership function.
|
|
:param kwargs: Keyword arguments to leadership function.
|
|
|
|
"""
|
|
if not callable(func):
|
|
raise ValueError("leader function is not callable")
|
|
|
|
try:
|
|
with self.lock:
|
|
func(*args, **kwargs)
|
|
|
|
except CancelledError:
|
|
pass
|
|
|
|
def cancel(self):
|
|
"""Cancel participation in the election
|
|
|
|
.. note::
|
|
|
|
If this contender has already been elected leader, this
|
|
method will not interrupt the leadership function.
|
|
|
|
"""
|
|
self.lock.cancel()
|
|
|
|
def contenders(self):
|
|
"""Return an ordered list of the current contenders in the
|
|
election
|
|
|
|
.. note::
|
|
|
|
If the contenders did not set an identifier, it will appear
|
|
as a blank string.
|
|
|
|
"""
|
|
return self.lock.contenders()
|