# -*- coding: utf-8 -*-
#
# Copyright (C) 2013-2014 eNovance Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from kazoo import client
from kazoo import exceptions
from kazoo import security
try:
from kazoo.handlers import eventlet as eventlet_handler
except ImportError:
eventlet_handler = None
from kazoo.handlers import threading as threading_handler
from kazoo.protocol import paths
from oslo_utils import encodeutils
from oslo_utils import strutils
import tooz
from tooz import coordination
from tooz import locking
from tooz import utils
class ZooKeeperLock(locking.Lock):
def __init__(self, name, lock):
super(ZooKeeperLock, self).__init__(name)
self._lock = lock
self._client = lock.client
def is_still_owner(self):
if not self.acquired:
return False
try:
data, _znode = self._client.get(
paths.join(self._lock.path, self._lock.node))
return data == self._lock.data
except (self._client.handler.timeout_exception,
exceptions.ConnectionLoss,
exceptions.ConnectionDropped,
exceptions.NoNodeError):
return False
except exceptions.KazooException as e:
utils.raise_with_cause(tooz.ToozError,
"operation error: %s" % (e),
cause=e)
def acquire(self, blocking=True, shared=False):
if shared:
raise tooz.NotImplemented
blocking, timeout = utils.convert_blocking(blocking)
return self._lock.acquire(blocking=blocking,
timeout=timeout)
def release(self):
if self.acquired:
self._lock.release()
return True
else:
return False
@property
def acquired(self):
return self._lock.is_acquired
[docs]class KazooDriver(coordination.CoordinationDriverCachedRunWatchers):
"""This driver uses the `kazoo`_ client against real `zookeeper`_ servers.
It **is** fully functional and implements all of the coordination
driver API(s). It stores data into `zookeeper`_ using znodes
and `msgpack`_ encoded values.
To configure the client to your liking a subset of the options defined at
http://kazoo.readthedocs.org/en/latest/api/client.html
will be extracted from the coordinator url (or any provided options),
so that a specific coordinator can be created that will work for you.
The Zookeeper coordinator url should look like::
zookeeper://[USERNAME:PASSWORD@][HOST[:PORT]][?OPTION1=VALUE1[&OPTION2=VALUE2[&...]]]
Currently the following options will be proxied to the contained client:
================ =============================== ====================
Name Source Default
================ =============================== ====================
hosts url netloc + 'hosts' option key localhost:2181
timeout 'timeout' options key 10.0 (kazoo default)
connection_retry 'connection_retry' options key None
command_retry 'command_retry' options key None
randomize_hosts 'randomize_hosts' options key True
================ =============================== ====================
.. _kazoo: http://kazoo.readthedocs.org/
.. _zookeeper: http://zookeeper.apache.org/
.. _msgpack: http://msgpack.org/
"""
#: Default namespace when none is provided.
TOOZ_NAMESPACE = b"tooz"
HANDLERS = {
'threading': threading_handler.SequentialThreadingHandler,
}
if eventlet_handler:
HANDLERS['eventlet'] = eventlet_handler.SequentialEventletHandler
"""
Restricted immutable dict of handler 'kinds' -> handler classes that
this driver can accept via 'handler' option key (the expected value for
this option is one of the keys in this dictionary).
"""
CHARACTERISTICS = (
coordination.Characteristics.NON_TIMEOUT_BASED,
coordination.Characteristics.DISTRIBUTED_ACROSS_THREADS,
coordination.Characteristics.DISTRIBUTED_ACROSS_PROCESSES,
coordination.Characteristics.DISTRIBUTED_ACROSS_HOSTS,
# Writes *always* go through a single leader process, but it may
# take a while for those writes to propagate to followers (and =
# during this time clients can read older values)...
coordination.Characteristics.SEQUENTIAL,
)
"""
Tuple of :py:class:`~tooz.coordination.Characteristics` introspectable
enum member(s) that can be used to interogate how this driver works.
"""
[docs] def __init__(self, member_id, parsed_url, options):
super(KazooDriver, self).__init__(member_id, parsed_url, options)
options = utils.collapse(options, exclude=['hosts'])
self.timeout = int(options.get('timeout', '10'))
self._namespace = options.get('namespace', self.TOOZ_NAMESPACE)
self._coord = self._make_client(parsed_url, options)
self._timeout_exception = self._coord.handler.timeout_exception
def _start(self):
try:
self._coord.start(timeout=self.timeout)
except self._coord.handler.timeout_exception as e:
e_msg = encodeutils.exception_to_unicode(e)
utils.raise_with_cause(coordination.ToozConnectionError,
"Operational error: %s" % e_msg,
cause=e)
try:
self._coord.ensure_path(self._paths_join("/", self._namespace))
except exceptions.KazooException as e:
e_msg = encodeutils.exception_to_unicode(e)
utils.raise_with_cause(tooz.ToozError,
"Operational error: %s" % e_msg,
cause=e)
self._leader_locks = {}
def _stop(self):
self._coord.stop()
@staticmethod
def _dumps(data):
return utils.dumps(data)
@staticmethod
def _loads(blob):
return utils.loads(blob)
def _create_group_handler(self, async_result, timeout,
timeout_exception, group_id):
try:
async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NodeExistsError:
raise coordination.GroupAlreadyExist(group_id)
except exceptions.NoNodeError as e:
utils.raise_with_cause(tooz.ToozError,
"Tooz namespace '%s' has not"
" been created" % self._namespace,
cause=e)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
[docs] def create_group(self, group_id):
group_path = self._path_group(group_id)
async_result = self._coord.create_async(group_path)
return ZooAsyncResult(async_result, self._create_group_handler,
timeout_exception=self._timeout_exception,
group_id=group_id)
@staticmethod
def _delete_group_handler(async_result, timeout,
timeout_exception, group_id):
try:
async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
raise coordination.GroupNotCreated(group_id)
except exceptions.NotEmptyError:
raise coordination.GroupNotEmpty(group_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
[docs] def delete_group(self, group_id):
group_path = self._path_group(group_id)
async_result = self._coord.delete_async(group_path)
return ZooAsyncResult(async_result, self._delete_group_handler,
timeout_exception=self._timeout_exception,
group_id=group_id)
@staticmethod
def _join_group_handler(async_result, timeout,
timeout_exception, group_id, member_id):
try:
async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NodeExistsError:
raise coordination.MemberAlreadyExist(group_id, member_id)
except exceptions.NoNodeError:
raise coordination.GroupNotCreated(group_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
[docs] def join_group(self, group_id, capabilities=b""):
member_path = self._path_member(group_id, self._member_id)
capabilities = self._dumps(capabilities)
async_result = self._coord.create_async(member_path,
value=capabilities,
ephemeral=True)
return ZooAsyncResult(async_result, self._join_group_handler,
timeout_exception=self._timeout_exception,
group_id=group_id, member_id=self._member_id)
@staticmethod
def _leave_group_handler(async_result, timeout,
timeout_exception, group_id, member_id):
try:
async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
raise coordination.MemberNotJoined(group_id, member_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
[docs] def heartbeat(self):
# Just fetch the base path (and do nothing with it); this will
# force any waiting heartbeat responses to be flushed, and also
# ensures that the connection still works as expected...
base_path = self._paths_join("/", self._namespace)
try:
self._coord.get(base_path)
except self._timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
pass
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
return self.timeout
[docs] def leave_group(self, group_id):
member_path = self._path_member(group_id, self._member_id)
async_result = self._coord.delete_async(member_path)
return ZooAsyncResult(async_result, self._leave_group_handler,
timeout_exception=self._timeout_exception,
group_id=group_id, member_id=self._member_id)
@staticmethod
def _get_members_handler(async_result, timeout,
timeout_exception, group_id):
try:
members_ids = async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
raise coordination.GroupNotCreated(group_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
else:
return set(m.encode('ascii') for m in members_ids)
[docs] def get_members(self, group_id):
group_path = self._paths_join("/", self._namespace, group_id)
async_result = self._coord.get_children_async(group_path)
return ZooAsyncResult(async_result, self._get_members_handler,
timeout_exception=self._timeout_exception,
group_id=group_id)
@staticmethod
def _update_capabilities_handler(async_result, timeout,
timeout_exception, group_id, member_id):
try:
async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
raise coordination.MemberNotJoined(group_id, member_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
[docs] def update_capabilities(self, group_id, capabilities):
member_path = self._path_member(group_id, self._member_id)
capabilities = self._dumps(capabilities)
async_result = self._coord.set_async(member_path, capabilities)
return ZooAsyncResult(async_result, self._update_capabilities_handler,
timeout_exception=self._timeout_exception,
group_id=group_id, member_id=self._member_id)
@classmethod
def _get_member_capabilities_handler(cls, async_result, timeout,
timeout_exception, group_id,
member_id):
try:
capabilities = async_result.get(block=True, timeout=timeout)[0]
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
raise coordination.MemberNotJoined(group_id, member_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
else:
return cls._loads(capabilities)
[docs] def get_member_capabilities(self, group_id, member_id):
member_path = self._path_member(group_id, member_id)
async_result = self._coord.get_async(member_path)
return ZooAsyncResult(async_result,
self._get_member_capabilities_handler,
timeout_exception=self._timeout_exception,
group_id=group_id, member_id=self._member_id)
@classmethod
def _get_member_info_handler(cls, async_result, timeout,
timeout_exception, group_id,
member_id):
try:
capabilities, znode_stats = async_result.get(block=True,
timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError:
raise coordination.MemberNotJoined(group_id, member_id)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
else:
member_info = {
'capabilities': cls._loads(capabilities),
'created_at': utils.millis_to_datetime(znode_stats.ctime),
'updated_at': utils.millis_to_datetime(znode_stats.mtime)
}
return member_info
[docs] def get_member_info(self, group_id, member_id):
member_path = self._path_member(group_id, member_id)
async_result = self._coord.get_async(member_path)
return ZooAsyncResult(async_result,
self._get_member_info_handler,
timeout_exception=self._timeout_exception,
group_id=group_id, member_id=self._member_id)
def _get_groups_handler(self, async_result, timeout, timeout_exception):
try:
group_ids = async_result.get(block=True, timeout=timeout)
except timeout_exception as e:
utils.raise_with_cause(coordination.OperationTimedOut,
encodeutils.exception_to_unicode(e),
cause=e)
except exceptions.NoNodeError as e:
utils.raise_with_cause(tooz.ToozError,
"Tooz namespace '%s' has not"
" been created" % self._namespace,
cause=e)
except exceptions.ZookeeperError as e:
utils.raise_with_cause(tooz.ToozError,
encodeutils.exception_to_unicode(e),
cause=e)
else:
return set(g.encode('ascii') for g in group_ids)
[docs] def get_groups(self):
tooz_namespace = self._paths_join("/", self._namespace)
async_result = self._coord.get_children_async(tooz_namespace)
return ZooAsyncResult(async_result, self._get_groups_handler,
timeout_exception=self._timeout_exception)
def _path_group(self, group_id):
return self._paths_join("/", self._namespace, group_id)
def _path_member(self, group_id, member_id):
return self._paths_join("/", self._namespace, group_id, member_id)
@staticmethod
def _paths_join(arg, *more_args):
"""Converts paths into a string (unicode)."""
args = [arg]
args.extend(more_args)
cleaned_args = []
for arg in args:
if isinstance(arg, bytes):
cleaned_args.append(
encodeutils.safe_decode(arg, incoming='ascii')
)
else:
cleaned_args.append(arg)
return paths.join(*cleaned_args)
def _make_client(self, parsed_url, options):
# Creates a kazoo client,
# See: https://github.com/python-zk/kazoo/blob/2.2.1/kazoo/client.py
# for what options a client takes...
if parsed_url.username and parsed_url.password:
username = parsed_url.username
password = parsed_url.password
digest_auth = "%s:%s" % (username, password)
digest_acl = security.make_digest_acl(username, password, all=True)
default_acl = (digest_acl,)
auth_data = [('digest', digest_auth)]
else:
default_acl = None
auth_data = None
maybe_hosts = [parsed_url.netloc] + list(options.get('hosts', []))
hosts = list(filter(None, maybe_hosts))
if not hosts:
hosts = ['localhost:2181']
randomize_hosts = options.get('randomize_hosts', True)
client_kwargs = {
'hosts': ",".join(hosts),
'timeout': float(options.get('timeout', self.timeout)),
'connection_retry': options.get('connection_retry'),
'command_retry': options.get('command_retry'),
'randomize_hosts': strutils.bool_from_string(randomize_hosts),
'auth_data': auth_data,
'default_acl': default_acl,
}
handler_kind = options.get('handler')
if handler_kind:
try:
handler_cls = self.HANDLERS[handler_kind]
except KeyError:
raise ValueError("Unknown handler '%s' requested"
" valid handlers are %s"
% (handler_kind,
sorted(self.HANDLERS.keys())))
client_kwargs['handler'] = handler_cls()
return client.KazooClient(**client_kwargs)
[docs] def stand_down_group_leader(self, group_id):
if group_id in self._leader_locks:
self._leader_locks[group_id].release()
return True
return False
def _get_group_leader_lock(self, group_id):
if group_id not in self._leader_locks:
self._leader_locks[group_id] = self._coord.Lock(
self._path_group(group_id) + "/leader",
encodeutils.safe_decode(self._member_id, incoming='ascii'))
return self._leader_locks[group_id]
[docs] def get_leader(self, group_id):
contenders = self._get_group_leader_lock(group_id).contenders()
if contenders and contenders[0]:
leader = contenders[0].encode('ascii')
else:
leader = None
return ZooAsyncResult(None, lambda *args: leader)
[docs] def get_lock(self, name):
z_lock = self._coord.Lock(
self._paths_join(b"/", self._namespace, b"locks", name),
encodeutils.safe_decode(self._member_id, incoming='ascii'))
return ZooKeeperLock(name, z_lock)
[docs] def run_elect_coordinator(self):
for group_id in self._hooks_elected_leader.keys():
leader_lock = self._get_group_leader_lock(group_id)
if leader_lock.is_acquired:
# Previously acquired/still leader, leave it be...
continue
if leader_lock.acquire(blocking=False):
# We are now leader for this group
self._hooks_elected_leader[group_id].run(
coordination.LeaderElected(
group_id,
self._member_id))
[docs] def run_watchers(self, timeout=None):
results = super(KazooDriver, self).run_watchers(timeout)
self.run_elect_coordinator()
return results
class ZooAsyncResult(coordination.CoordAsyncResult):
def __init__(self, kazoo_async_result, handler, **kwargs):
self._kazoo_async_result = kazoo_async_result
self._handler = handler
self._kwargs = kwargs
def get(self, timeout=None):
return self._handler(self._kazoo_async_result, timeout, **self._kwargs)
def done(self):
return self._kazoo_async_result.ready()
