205 lines
6.5 KiB
Python
205 lines
6.5 KiB
Python
# -*- coding: utf-8 -*-
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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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from __future__ import absolute_import
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import base64
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import threading
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import uuid
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import etcd3gw
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from etcd3gw import exceptions as etcd3_exc
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from oslo_utils import encodeutils
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import six
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import tooz
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from tooz import _retry
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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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def _translate_failures(func):
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"""Translates common requests exceptions into tooz exceptions."""
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@six.wraps(func)
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def wrapper(*args, **kwargs):
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try:
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return func(*args, **kwargs)
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except etcd3_exc.ConnectionFailedError as e:
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utils.raise_with_cause(coordination.ToozConnectionError,
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encodeutils.exception_to_unicode(e),
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cause=e)
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except etcd3_exc.ConnectionTimeoutError as e:
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utils.raise_with_cause(coordination.OperationTimedOut,
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encodeutils.exception_to_unicode(e),
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cause=e)
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except etcd3_exc.Etcd3Exception as e:
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utils.raise_with_cause(coordination.ToozError,
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encodeutils.exception_to_unicode(e),
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cause=e)
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return wrapper
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class Etcd3Lock(locking.Lock):
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"""An etcd3-specific lock.
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Thin wrapper over etcd3's lock object basically to provide the heartbeat()
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semantics for the coordination driver.
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"""
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LOCK_PREFIX = b"/tooz/locks"
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def __init__(self, coord, name, timeout):
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super(Etcd3Lock, self).__init__(name)
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self._timeout = timeout
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self._coord = coord
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self._key = self.LOCK_PREFIX + name
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self._key_b64 = base64.b64encode(self._key).decode("ascii")
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self._uuid = base64.b64encode(uuid.uuid4().bytes).decode("ascii")
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self._lease = self._coord.client.lease(self._timeout)
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self._exclusive_access = threading.Lock()
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@_translate_failures
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def acquire(self, blocking=True, shared=False):
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if shared:
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raise tooz.NotImplemented
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@_retry.retry(stop_max_delay=blocking)
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def _acquire():
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# TODO(jd): save the created revision so we can check it later to
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# make sure we still have the lock
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txn = {
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'compare': [{
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'key': self._key_b64,
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'result': 'EQUAL',
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'target': 'CREATE',
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'create_revision': 0
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}],
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'success': [{
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'request_put': {
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'key': self._key_b64,
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'value': self._uuid,
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'lease': self._lease.id
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}
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}],
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'failure': [{
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'request_range': {
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'key': self._key_b64
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}
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}]
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}
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result = self._coord.client.transaction(txn)
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success = result.get('succeeded', False)
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if success is not True:
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if blocking is False:
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return False
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raise _retry.TryAgain
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self._coord._acquired_locks.add(self)
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return True
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return _acquire()
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@_translate_failures
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def release(self):
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txn = {
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'compare': [{
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'key': self._key_b64,
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'result': 'EQUAL',
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'target': 'VALUE',
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'value': self._uuid
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}],
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'success': [{
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'request_delete_range': {
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'key': self._key_b64
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}
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}]
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}
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with self._exclusive_access:
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result = self._coord.client.transaction(txn)
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success = result.get('succeeded', False)
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if success:
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self._coord._acquired_locks.remove(self)
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return True
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return False
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@_translate_failures
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def break_(self):
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if self._coord.client.delete(self._key):
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self._coord._acquired_locks.discard(self)
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return True
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return False
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@property
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def acquired(self):
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return self in self._coord._acquired_locks
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@_translate_failures
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def heartbeat(self):
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with self._exclusive_access:
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if self.acquired:
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self._lease.refresh()
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return True
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return False
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class Etcd3Driver(coordination.CoordinationDriver):
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"""An etcd based driver.
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This driver uses etcd provide the coordination driver semantics and
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required API(s).
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"""
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#: Default socket/lock/member/leader timeout used when none is provided.
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DEFAULT_TIMEOUT = 30
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#: Default hostname used when none is provided.
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DEFAULT_HOST = "localhost"
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#: Default port used if none provided (4001 or 2379 are the common ones).
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DEFAULT_PORT = 2379
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def __init__(self, member_id, parsed_url, options):
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super(Etcd3Driver, self).__init__(member_id, parsed_url, options)
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host = parsed_url.hostname or self.DEFAULT_HOST
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port = parsed_url.port or self.DEFAULT_PORT
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options = utils.collapse(options)
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timeout = int(options.get('timeout', self.DEFAULT_TIMEOUT))
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self.client = etcd3gw.client(host=host, port=port, timeout=timeout)
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self.lock_timeout = int(options.get('lock_timeout', timeout))
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self._acquired_locks = set()
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def get_lock(self, name):
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return Etcd3Lock(self, name, self.lock_timeout)
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def heartbeat(self):
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# NOTE(jaypipes): Copying because set can mutate during iteration
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for lock in self._acquired_locks.copy():
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lock.heartbeat()
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return self.lock_timeout
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def watch_join_group(self, group_id, callback):
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raise tooz.NotImplemented
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def unwatch_join_group(self, group_id, callback):
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raise tooz.NotImplemented
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def watch_leave_group(self, group_id, callback):
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raise tooz.NotImplemented
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def unwatch_leave_group(self, group_id, callback):
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raise tooz.NotImplemented
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