529 lines
22 KiB
Python
529 lines
22 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright (C) 2013-2014 eNovance Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import collections
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import copy
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from kazoo import client
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from kazoo import exceptions
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from kazoo.protocol import paths
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from oslo_utils import strutils
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import six
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from six.moves import filter as compat_filter
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from tooz import coordination
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from tooz import locking
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from tooz import utils
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class ZooKeeperLock(locking.Lock):
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def __init__(self, name, lock):
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super(ZooKeeperLock, self).__init__(name)
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self._lock = lock
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self.acquired = False
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def acquire(self, blocking=True):
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if isinstance(blocking, bool):
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timeout = None
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else:
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blocking = True
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timeout = float(blocking)
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self.acquired = self._lock.acquire(blocking=blocking,
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timeout=timeout)
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return self.acquired
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def release(self):
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if self.acquired:
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self._lock.release()
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self.acquired = False
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return True
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else:
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return False
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class BaseZooKeeperDriver(coordination.CoordinationDriver):
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"""Initialize the zookeeper driver.
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:param timeout: connection timeout to wait when first connecting to the
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zookeeper server
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"""
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#: Default namespace when none is provided.
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TOOZ_NAMESPACE = b"tooz"
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def __init__(self, member_id, parsed_url, options):
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super(BaseZooKeeperDriver, self).__init__()
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options = utils.collapse(options, exclude=['hosts'])
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self._options = options
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self._member_id = member_id
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self.timeout = int(options.get('timeout', '10'))
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self._namespace = options.get('namespace', self.TOOZ_NAMESPACE)
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def _start(self):
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try:
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self._coord.start(timeout=self.timeout)
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except self._coord.handler.timeout_exception as e:
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coordination.raise_with_cause(coordination.ToozConnectionError,
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"operation error: %s" % (e),
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cause=e)
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try:
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self._coord.ensure_path(self.paths_join("/", self._namespace))
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except exceptions.KazooException as e:
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coordination.raise_with_cause(coordination.ToozError,
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"operation error: %s" % (e),
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cause=e)
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self._group_members = collections.defaultdict(set)
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self._watchers = collections.deque()
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self._leader_locks = {}
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def _stop(self):
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self._coord.stop()
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@staticmethod
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def _dumps(data):
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return utils.dumps(data)
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@staticmethod
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def _loads(blob):
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return utils.loads(blob)
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@staticmethod
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def _create_group_handler(async_result, timeout,
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timeout_exception, group_id):
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try:
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async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NodeExistsError:
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raise coordination.GroupAlreadyExist(group_id)
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except exceptions.NoNodeError:
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raise coordination.ToozError("tooz namespace has not been created")
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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def create_group(self, group_id):
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group_path = self._path_group(group_id)
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async_result = self._coord.create_async(group_path)
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return ZooAsyncResult(async_result, self._create_group_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id)
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@staticmethod
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def _delete_group_handler(async_result, timeout,
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timeout_exception, group_id):
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try:
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async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NoNodeError:
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raise coordination.GroupNotCreated(group_id)
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except exceptions.NotEmptyError:
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raise coordination.GroupNotEmpty(group_id)
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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def delete_group(self, group_id):
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group_path = self._path_group(group_id)
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async_result = self._coord.delete_async(group_path)
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return ZooAsyncResult(async_result, self._delete_group_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id)
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@staticmethod
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def _join_group_handler(async_result, timeout,
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timeout_exception, group_id, member_id):
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try:
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async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NodeExistsError:
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raise coordination.MemberAlreadyExist(group_id, member_id)
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except exceptions.NoNodeError:
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raise coordination.GroupNotCreated(group_id)
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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def join_group(self, group_id, capabilities=b""):
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member_path = self._path_member(group_id, self._member_id)
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capabilities = self._dumps(capabilities)
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async_result = self._coord.create_async(member_path,
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value=capabilities,
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ephemeral=True)
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return ZooAsyncResult(async_result, self._join_group_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id, member_id=self._member_id)
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@staticmethod
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def _leave_group_handler(async_result, timeout,
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timeout_exception, group_id, member_id):
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try:
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async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NoNodeError:
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raise coordination.MemberNotJoined(group_id, member_id)
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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def leave_group(self, group_id):
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member_path = self._path_member(group_id, self._member_id)
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async_result = self._coord.delete_async(member_path)
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return ZooAsyncResult(async_result, self._leave_group_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id, member_id=self._member_id)
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@staticmethod
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def _get_members_handler(async_result, timeout,
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timeout_exception, group_id):
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try:
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members_ids = async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NoNodeError:
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raise coordination.GroupNotCreated(group_id)
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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else:
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return set(m.encode('ascii') for m in members_ids)
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def get_members(self, group_id):
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group_path = self.paths_join("/", self._namespace, group_id)
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async_result = self._coord.get_children_async(group_path)
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return ZooAsyncResult(async_result, self._get_members_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id)
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@staticmethod
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def _update_capabilities_handler(async_result, timeout,
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timeout_exception, group_id, member_id):
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try:
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async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NoNodeError:
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raise coordination.MemberNotJoined(group_id, member_id)
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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def update_capabilities(self, group_id, capabilities):
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member_path = self._path_member(group_id, self._member_id)
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capabilities = self._dumps(capabilities)
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async_result = self._coord.set_async(member_path, capabilities)
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return ZooAsyncResult(async_result, self._update_capabilities_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id, member_id=self._member_id)
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@classmethod
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def _get_member_capabilities_handler(cls, async_result, timeout,
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timeout_exception, group_id,
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member_id):
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try:
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capabilities = async_result.get(block=True, timeout=timeout)[0]
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NoNodeError:
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raise coordination.MemberNotJoined(group_id, member_id)
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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else:
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return cls._loads(capabilities)
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def get_member_capabilities(self, group_id, member_id):
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member_path = self._path_member(group_id, member_id)
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async_result = self._coord.get_async(member_path)
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return ZooAsyncResult(async_result,
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self._get_member_capabilities_handler,
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timeout_exception=self._timeout_exception,
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group_id=group_id, member_id=self._member_id)
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@staticmethod
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def _get_groups_handler(async_result, timeout, timeout_exception):
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try:
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group_ids = async_result.get(block=True, timeout=timeout)
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except timeout_exception as e:
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coordination.raise_with_cause(coordination.OperationTimedOut,
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utils.exception_message(e),
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cause=e)
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except exceptions.NoNodeError:
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raise coordination.ToozError("tooz namespace has not been created")
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except exceptions.ZookeeperError as e:
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coordination.raise_with_cause(coordination.ToozError,
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utils.exception_message(e),
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cause=e)
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else:
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return set(g.encode('ascii') for g in group_ids)
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def get_groups(self):
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tooz_namespace = self.paths_join("/", self._namespace)
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async_result = self._coord.get_children_async(tooz_namespace)
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return ZooAsyncResult(async_result, self._get_groups_handler,
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timeout_exception=self._timeout_exception)
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def _path_group(self, group_id):
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return self.paths_join("/", self._namespace, group_id)
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def _path_member(self, group_id, member_id):
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return self.paths_join("/", self._namespace,
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group_id, member_id)
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@staticmethod
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def paths_join(*args):
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lpaths = []
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for arg in args:
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if isinstance(arg, six.binary_type):
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lpaths.append(arg.decode('ascii'))
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else:
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lpaths.append(arg)
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return paths.join(*lpaths)
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class KazooDriver(BaseZooKeeperDriver):
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"""This driver uses the `kazoo`_ client against real `zookeeper`_ servers.
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It **is** fully functional and implements all of the coordination
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driver API(s). It stores data into `zookeeper`_ using znodes
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and `msgpack`_ encoded values.
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To configure the client to your liking a subset of the options defined at
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http://kazoo.readthedocs.org/en/latest/api/client.html
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will be extracted from the coordinator url (or any provided options),
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so that a specific coordinator can be created that will work for you.
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Currently the following options will be proxied to the contained client:
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================ =============================== ====================
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Name Source Default
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================ =============================== ====================
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hosts url netloc + 'hosts' option key localhost:2181
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timeout 'timeout' options key 10.0 (kazoo default)
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connection_retry 'connection_retry' options key None
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command_retry 'command_retry' options key None
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randomize_hosts 'randomize_hosts' options key True
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================ =============================== ====================
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.. _kazoo: http://kazoo.readthedocs.org/
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.. _zookeeper: http://zookeeper.apache.org/
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.. _msgpack: http://msgpack.org/
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"""
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def __init__(self, member_id, parsed_url, options):
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super(KazooDriver, self).__init__(member_id, parsed_url, options)
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self._coord = self._make_client(parsed_url, self._options)
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self._member_id = member_id
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self._timeout_exception = self._coord.handler.timeout_exception
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def _make_client(self, parsed_url, options):
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# Creates a kazoo client,
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# See: https://github.com/python-zk/kazoo/blob/2.2.1/kazoo/client.py
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# for what options a client takes...
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maybe_hosts = [parsed_url.netloc] + list(options.get('hosts', []))
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hosts = list(compat_filter(None, maybe_hosts))
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if not hosts:
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hosts = ['localhost:2181']
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randomize_hosts = options.get('randomize_hosts', True)
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client_kwargs = {
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'hosts': ",".join(hosts),
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'timeout': float(options.get('timeout', self.timeout)),
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'connection_retry': options.get('connection_retry'),
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'command_retry': options.get('command_retry'),
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'randomize_hosts': strutils.bool_from_string(randomize_hosts),
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}
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return client.KazooClient(**client_kwargs)
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def _watch_group(self, group_id):
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get_members_req = self.get_members(group_id)
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def on_children_change(children):
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# If we don't have any hook, stop watching
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if not self._has_hooks_for_group(group_id):
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return False
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children = set(children)
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last_children = self._group_members[group_id]
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for member_id in (children - last_children):
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# Copy function in case it's removed later from the
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# hook list
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hooks = copy.copy(self._hooks_join_group[group_id])
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self._watchers.append(
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lambda: hooks.run(
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coordination.MemberJoinedGroup(
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group_id,
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utils.to_binary(member_id))))
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for member_id in (last_children - children):
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# Copy function in case it's removed later from the
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# hook list
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hooks = copy.copy(self._hooks_leave_group[group_id])
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self._watchers.append(
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lambda: hooks.run(
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coordination.MemberLeftGroup(
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group_id,
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utils.to_binary(member_id))))
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self._group_members[group_id] = children
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# Initialize the current member list
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self._group_members[group_id] = get_members_req.get()
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try:
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self._coord.ChildrenWatch(self._path_group(group_id),
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on_children_change)
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except exceptions.NoNodeError:
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raise coordination.GroupNotCreated(group_id)
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def watch_join_group(self, group_id, callback):
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# Check if we already have hooks for this group_id, if not, start
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# watching it.
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already_being_watched = self._has_hooks_for_group(group_id)
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# Add the hook before starting watching to avoid race conditions
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# as the watching executor can be in a thread
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super(BaseZooKeeperDriver, self).watch_join_group(
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group_id, callback)
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if not already_being_watched:
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try:
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self._watch_group(group_id)
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except Exception:
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# Rollback and unregister the hook
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self.unwatch_join_group(group_id, callback)
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raise
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def unwatch_join_group(self, group_id, callback):
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return super(BaseZooKeeperDriver, self).unwatch_join_group(
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group_id, callback)
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def watch_leave_group(self, group_id, callback):
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# Check if we already have hooks for this group_id, if not, start
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# watching it.
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already_being_watched = self._has_hooks_for_group(group_id)
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# Add the hook before starting watching to avoid race conditions
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# as the watching executor can be in a thread
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super(BaseZooKeeperDriver, self).watch_leave_group(
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group_id, callback)
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if not already_being_watched:
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try:
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self._watch_group(group_id)
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except Exception:
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# Rollback and unregister the hook
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self.unwatch_leave_group(group_id, callback)
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raise
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def unwatch_leave_group(self, group_id, callback):
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return super(BaseZooKeeperDriver, self).unwatch_leave_group(
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group_id, callback)
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def watch_elected_as_leader(self, group_id, callback):
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return super(BaseZooKeeperDriver, self).watch_elected_as_leader(
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group_id, callback)
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def unwatch_elected_as_leader(self, group_id, callback):
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return super(BaseZooKeeperDriver, self).unwatch_elected_as_leader(
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group_id, callback)
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def stand_down_group_leader(self, group_id):
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if group_id in self._leader_locks:
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self._leader_locks[group_id].release()
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return True
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return False
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def _get_group_leader_lock(self, group_id):
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if group_id not in self._leader_locks:
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self._leader_locks[group_id] = self._coord.Lock(
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self._path_group(group_id) + "/leader",
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self._member_id.decode('ascii'))
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return self._leader_locks[group_id]
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def get_leader(self, group_id):
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contenders = self._get_group_leader_lock(group_id).contenders()
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if contenders and contenders[0]:
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leader = contenders[0].encode('ascii')
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else:
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leader = None
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return ZooAsyncResult(None, lambda *args: leader)
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def get_lock(self, name):
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return ZooKeeperLock(
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name,
|
|
self._coord.Lock(
|
|
self.paths_join(b"/", self._namespace, b"locks", name),
|
|
self._member_id.decode('ascii')))
|
|
|
|
def run_elect_coordinator(self):
|
|
for group_id in six.iterkeys(self._hooks_elected_leader):
|
|
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))
|
|
|
|
def run_watchers(self, timeout=None):
|
|
results = []
|
|
while self._watchers:
|
|
cb = self._watchers.popleft()
|
|
results.extend(cb())
|
|
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=10):
|
|
return self._handler(self._kazoo_async_result, timeout, **self._kwargs)
|
|
|
|
def done(self):
|
|
return self._kazoo_async_result.ready()
|