Add etcd3 group support
Sem-Ver: feature Change-Id: I1ce3a61c8e28b874df3583e08aa6a70f9506dd11
This commit is contained in:
Julien Danjou
parent
f947d1f377
commit
e1af969a68
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@ -0,0 +1,4 @@
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---
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features:
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- |
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The etcd3 driver now supports the group membership API.
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@ -13,6 +13,8 @@
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# under the License.
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from __future__ import absolute_import
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import contextlib
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import functools
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import threading
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import etcd3
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@ -21,30 +23,37 @@ 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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@contextlib.contextmanager
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def _failure_translator():
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"""Translates common requests exceptions into tooz exceptions."""
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try:
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yield
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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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def _translate_failures(func):
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@six.wraps(func)
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def wrapper(*args, **kwargs):
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try:
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with _failure_translator():
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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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@ -100,7 +109,8 @@ class Etcd3Lock(locking.Lock):
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return False
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class Etcd3Driver(coordination.CoordinationDriver):
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class Etcd3Driver(coordination.CoordinationDriverCachedRunWatchers,
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coordination.CoordinationDriverWithExecutor):
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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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@ -124,8 +134,18 @@ class Etcd3Driver(coordination.CoordinationDriver):
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timeout = int(options.get('timeout', self.DEFAULT_TIMEOUT))
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self.client = etcd3.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.membership_timeout = int(options.get(
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'membership_timeout', timeout))
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self._acquired_locks = set()
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def _start(self):
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super(Etcd3Driver, self)._start()
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self._membership_lease = self.client.lease(self.membership_timeout)
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def _stop(self):
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super(Etcd3Driver, self)._stop()
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self._membership_lease.revoke()
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def get_lock(self, name):
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return Etcd3Lock(self, name, self.lock_timeout)
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@ -133,16 +153,191 @@ class Etcd3Driver(coordination.CoordinationDriver):
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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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# TODO(jd) use the same lease for locks?
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self._membership_lease.refresh()
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return min(self.lock_timeout, self.membership_timeout)
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def watch_join_group(self, group_id, callback):
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GROUP_PREFIX = b"tooz/groups/"
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def _encode_group_id(self, group_id):
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return self.GROUP_PREFIX + group_id + b"/"
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def _encode_group_member_id(self, group_id, member_id):
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return self._encode_group_id(group_id) + member_id
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def create_group(self, group_id):
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encoded_group = self._encode_group_id(group_id)
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@_translate_failures
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def _create_group():
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status, results = self.client.transaction(
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compare=[
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self.client.transactions.version(
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encoded_group) == 0
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],
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success=[
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self.client.transactions.put(encoded_group, b"")
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],
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failure=[],
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)
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if not status:
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raise coordination.GroupAlreadyExist(group_id)
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return EtcdFutureResult(self._executor.submit(_create_group))
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def _destroy_group(self, group_id):
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self.client.delete(self._encode_group_id(group_id))
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def delete_group(self, group_id):
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encoded_group = self._encode_group_id(group_id)
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@_translate_failures
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def _delete_group():
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members = list(self.client.get_prefix(encoded_group))
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if len(members) > 1:
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raise coordination.GroupNotEmpty(group_id)
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# Warning: as of this writing python-etcd3 does not support the
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# NOT_EQUAL operator so we use the EQUAL operator and will retry on
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# success, hihi
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status, results = self.client.transaction(
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compare=[
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self.client.transactions.version(encoded_group) == 0
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],
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success=[],
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failure=[
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self.client.transactions.delete(encoded_group)
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],
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)
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if status:
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raise coordination.GroupNotCreated(group_id)
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return EtcdFutureResult(self._executor.submit(_delete_group))
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def join_group(self, group_id, capabilities=b""):
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encoded_group = self._encode_group_id(group_id)
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@_retry.retry()
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@_translate_failures
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def _join_group():
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members = list(self.client.get_prefix(encoded_group))
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encoded_member = self._encode_group_member_id(
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group_id, self._member_id)
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group_metadata = None
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for cap, metadata in members:
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if metadata.key == encoded_member:
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raise coordination.MemberAlreadyExist(group_id,
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self._member_id)
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if metadata.key == encoded_group:
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group_metadata = metadata
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if group_metadata is None:
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raise coordination.GroupNotCreated(group_id)
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status, results = self.client.transaction(
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# This comparison makes sure the group has not been deleted in
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# the mean time
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compare=[
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self.client.transactions.version(encoded_group) ==
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group_metadata.version
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],
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success=[
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self.client.transactions.put(encoded_member,
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utils.dumps(capabilities),
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lease=self._membership_lease)
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],
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failure=[],
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)
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if not status:
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# TODO(jd) There's a small optimization doable by getting the
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# current range on failure and passing it to this function as
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# the first arg when retrying to avoid redoing a get_prefix()
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raise _retry.TryAgain
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return EtcdFutureResult(self._executor.submit(_join_group))
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def leave_group(self, group_id):
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encoded_group = self._encode_group_id(group_id)
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@_translate_failures
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def _leave_group():
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members = list(self.client.get_prefix(encoded_group))
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encoded_member = self._encode_group_member_id(
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group_id, self._member_id)
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for capabilities, metadata in members:
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if metadata.key == encoded_member:
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break
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else:
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raise coordination.MemberNotJoined(group_id,
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self._member_id)
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self.client.delete(encoded_member)
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return EtcdFutureResult(self._executor.submit(_leave_group))
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def get_members(self, group_id):
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encoded_group = self._encode_group_id(group_id)
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@_translate_failures
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def _get_members():
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members = set()
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group_found = False
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for cap, metadata in self.client.get_prefix(encoded_group):
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if metadata.key == encoded_group:
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group_found = True
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else:
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members.add(metadata.key[len(encoded_group):])
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if not group_found:
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raise coordination.GroupNotCreated(group_id)
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return members
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return EtcdFutureResult(self._executor.submit(_get_members))
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def get_member_capabilities(self, group_id, member_id):
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encoded_member = self._encode_group_member_id(
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group_id, member_id)
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@_translate_failures
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def _get_member_capabilities():
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capabilities, metadata = self.client.get(encoded_member)
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if capabilities is None:
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raise coordination.MemberNotJoined(group_id, member_id)
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return utils.loads(capabilities)
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return EtcdFutureResult(
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self._executor.submit(_get_member_capabilities))
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def update_capabilities(self, group_id, capabilities):
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encoded_member = self._encode_group_member_id(
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group_id, self._member_id)
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@_translate_failures
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def _update_capabilities():
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cap, metadata = self.client.get(encoded_member)
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if cap is None:
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raise coordination.MemberNotJoined(group_id, self._member_id)
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self.client.put(encoded_member, utils.dumps(capabilities),
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lease=self._membership_lease)
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return EtcdFutureResult(
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self._executor.submit(_update_capabilities))
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@staticmethod
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def watch_elected_as_leader(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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@staticmethod
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def unwatch_elected_as_leader(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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EtcdFutureResult = functools.partial(coordination.CoordinatorResult,
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failure_translator=_failure_translator)
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