OpenStack Study: kvs.py

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# 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.

import datetime

from keystone.common import kvs

from keystone import config

from keystone.contrib import revoke

from keystone import exception

from keystone.openstack.common import timeutils

CONF = config.CONF

_EVENT_KEY = 'os-revoke-events'

_KVS_BACKEND = 'openstack.kvs.Memory'

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class Revoke(revoke.Driver):

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    def __init__(self, **kwargs):

        super(Revoke, self).__init__()

        self._store = kvs.get_key_value_store('os-revoke-driver')

        self._store.configure(backing_store=_KVS_BACKEND, **kwargs)

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    def _get_event(self):

        try:

            return self._store.get(_EVENT_KEY)

        except exception.NotFound:

            return []

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    def _prune_expired_events_and_get(self, last_fetch=None, new_event=None):

        pruned = []

        results = []

        expire_delta = datetime.timedelta(seconds=CONF.token.expiration)

        oldest = timeutils.utcnow() - expire_delta

        # TODO(ayoung): Store the time of the oldest event so that the

        # prune process can be skipped if none of the events have timed out.

        with self._store.get_lock(_EVENT_KEY) as lock:

            events = self._get_event()

            if new_event is not None:

                events.append(new_event)

            for event in events:

                revoked_at = event.revoked_at

                if revoked_at > oldest:

                    pruned.append(event)

                    if last_fetch is None or revoked_at > last_fetch:

                        results.append(event)

            self._store.set(_EVENT_KEY, pruned, lock)

        return results

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    def get_events(self, last_fetch=None):

        return self._prune_expired_events_and_get(last_fetch=last_fetch)

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    def revoke(self, event):

        self._prune_expired_events_and_get(new_event=event)