a134930dd5
Create a base implementation of a jobboard which serves as a place to post work to be done, a place to get notified of new work, and a place which can be used to atomically acquire that work (so that it can be worked on) as well as transfer that work from one entity (say when that entity fails) to another entity (for further resumption or other policy/code driven recovery processes). Implements: blueprint job-reference-impl Change-Id: I1de1525df0deee612fb14ca36f0415ea7d2f707c
483 lines
20 KiB
Python
483 lines
20 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2013 Yahoo! 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 contextlib
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import functools
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import logging
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from kazoo import exceptions as k_exceptions
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from kazoo.protocol import paths as k_paths
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from kazoo.recipe import watchers
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import six
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from taskflow import exceptions as excp
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from taskflow.jobs import job as base_job
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from taskflow.jobs import jobboard
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from taskflow.openstack.common import excutils
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from taskflow.openstack.common import jsonutils
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from taskflow.persistence import logbook
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from taskflow import states
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from taskflow.utils import kazoo_utils
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from taskflow.utils import lock_utils
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from taskflow.utils import misc
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LOG = logging.getLogger(__name__)
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UNCLAIMED_JOB_STATES = (
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states.UNCLAIMED,
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)
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ALL_JOB_STATES = (
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states.UNCLAIMED,
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states.COMPLETE,
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states.CLAIMED,
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)
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# Transaction support was added in 3.4.0
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MIN_ZK_VERSION = (3, 4, 0)
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# Used to ensure that watchers don't try to overwrite jobs that are still being
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# posted (and may have not been completly posted yet), these jobs should not be
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# yield back until they are in the ready state.
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_READY = 'ready'
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_POSTING = 'posting'
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def _get_paths(base_path, job_uuid):
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job_path = k_paths.join(base_path, job_uuid)
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lock_path = k_paths.join(base_path, job_uuid, 'lock')
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return (job_path, lock_path)
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def _check_who(who):
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if not isinstance(who, six.string_types):
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raise TypeError("Job applicant must be a string type")
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if len(who) == 0:
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raise ValueError("Job applicant must be non-empty")
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class ZookeeperJob(base_job.Job):
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def __init__(self, name, board, client, backend,
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uuid=None, details=None, book=None, book_data=None):
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super(ZookeeperJob, self).__init__(name, uuid=uuid, details=details)
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self._board = board
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self._book = book
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if not book_data:
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book_data = {}
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self._book_data = book_data
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self._client = client
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self._backend = backend
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if all((self._book, self._book_data)):
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raise ValueError("Only one of 'book_data' or 'book'"
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" can be provided")
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@property
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def board(self):
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return self._board
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def _load_book(self, book_uuid, book_name):
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# No backend to attempt to fetch from :-(
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if self._backend is None:
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return logbook.LogBook(name=book_name, uuid=book_uuid)
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# TODO(harlowja): we are currently limited by assuming that the job
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# posted has the same backend as this loader (to start this seems to
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# be a ok assumption, and can be adjusted in the future if we determine
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# there is a use-case for multi-backend loaders, aka a registry of
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# loaders).
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with contextlib.closing(self._backend.get_connection()) as conn:
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return conn.get_logbook(book_uuid)
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@property
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def state(self):
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owner = self.board.find_owner(self)
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job_data = {}
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job_path, _lock_path = _get_paths(self.board.path, self.uuid)
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try:
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raw_data, _data_stat = self._client.get(job_path)
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job_data = misc.decode_json(raw_data)
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except k_exceptions.NoNodeError:
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pass
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except k_exceptions.SessionExpiredError:
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raise excp.ConnectionFailure("Can not fetch the state of %s,"
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" session expired" % (self.uuid))
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except self._client.handler.timeout_exception:
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raise excp.ConnectionFailure("Can not fetch the state of %s,"
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" connection timed out" % (self.uuid))
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except k_exceptions.KazooException as e:
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raise excp.InvalidJobOperation("Can not fetch the state of %s,"
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" internal error: %s"
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% (self.uuid, e))
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if not job_data:
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# No data this job has been completed (the owner that we might have
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# fetched will not be able to be fetched again, since the job node
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# is a parent node of the owner/lock node).
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return states.COMPLETE
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if not owner:
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# No owner, but data, still work to be done.
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return states.UNCLAIMED
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return states.CLAIMED
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@property
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def book(self):
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if self._book is None:
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loaded_book = None
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try:
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book_uuid = self._book_data['uuid']
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book_name = self._book_data['name']
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loaded_book = self._load_book(book_uuid, book_name)
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except (KeyError, TypeError):
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pass
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self._book = loaded_book
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return self._book
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class ZookeeperJobBoard(jobboard.JobBoard):
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def __init__(self, name, conf, client=None):
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super(ZookeeperJobBoard, self).__init__(name)
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self._conf = conf
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if client is not None:
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self._client = client
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self._owned = False
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else:
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self._client = kazoo_utils.make_client(self._conf)
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self._owned = True
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path = str(conf.get("path", "/taskflow/jobs"))
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if not path:
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raise ValueError("Empty zookeeper path is disallowed")
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if not k_paths.isabs(path):
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raise ValueError("Zookeeper path must be absolute")
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self._path = path
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# The backend to load the full logbooks from, since whats sent over
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# the zookeeper data connection is only the logbook uuid and name, and
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# not currently the full logbook (later when a zookeeper backend
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# appears we can likely optimize for that backend usage by directly
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# reading from the path where the data is stored, if we want).
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self._persistence = self._conf.get("persistence")
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# Misc. internal details
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self._known_jobs = {}
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self._job_mutate = self._client.handler.rlock_object()
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self._open_close_lock = self._client.handler.rlock_object()
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self._client.add_listener(self._state_change_listener)
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self._bad_paths = frozenset([path])
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self._job_watcher = None
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@property
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def path(self):
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return self._path
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@property
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def job_count(self):
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with self._job_mutate:
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known_jobs = list(six.itervalues(self._known_jobs))
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count = 0
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for (_job, posting_state) in known_jobs:
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if posting_state != _READY:
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continue
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count += 1
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return count
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def iterjobs(self, only_unclaimed=False):
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ok_states = ALL_JOB_STATES
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if only_unclaimed:
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ok_states = UNCLAIMED_JOB_STATES
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with self._job_mutate:
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known_jobs = list(six.itervalues(self._known_jobs))
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for (job, posting_state) in known_jobs:
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if posting_state != _READY:
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continue
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try:
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if job.state in ok_states:
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yield job
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except (excp.InvalidJobOperation, excp.ConnectionFailure) as e:
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LOG.warn("Failed determining the state of job %s"
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" due to: %s", job.uuid, e)
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def _remove_job(self, path):
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LOG.debug("Removing job that was at path: %s", path)
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self._known_jobs.pop(path, None)
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def _process_child(self, path, request):
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"""Receives the result of a child data fetch request."""
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try:
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raw_data, _stat = request.get()
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job_data = misc.decode_json(raw_data)
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with self._job_mutate:
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if path not in self._known_jobs:
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job = ZookeeperJob(job_data['name'], self,
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self._client, self._persistence,
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uuid=job_data['uuid'],
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book_data=job_data.get("book"),
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details=job_data.get("details", {}))
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self._known_jobs[path] = (job, _READY)
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except (ValueError, TypeError, KeyError):
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LOG.exception("Incorrectly formatted job data found"
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" at path: %s", path)
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except self._client.handler.timeout_exception:
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LOG.warn("Connection timed out fetching job data"
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" from path: %s", path)
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except k_exceptions.SessionExpiredError:
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LOG.warn("Session expired fetching job data from path: %s", path)
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except k_exceptions.NoNodeError:
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LOG.warn("No job node found at path: %s, it must have"
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" disappeared or was removed", path)
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except k_exceptions.KazooException:
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LOG.exception("Internal error fetching job data from"
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" path: %s", path)
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def _on_job_posting(self, children):
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LOG.debug("Got children %s under path %s", children, self.path)
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child_paths = [k_paths.join(self.path, c) for c in children]
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# Remove jobs that we know about but which are no longer children
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with self._job_mutate:
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removals = set()
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for path, (_job, posting_state) in six.iteritems(self._known_jobs):
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if posting_state != _READY:
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continue
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if path not in child_paths:
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removals.add(path)
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for path in removals:
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self._remove_job(path)
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# Ensure that we have a job record for each new job that has appeared
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for path in child_paths:
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if path in self._bad_paths:
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continue
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with self._job_mutate:
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if path not in self._known_jobs:
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# Fire off the request to populate this job asynchronously.
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#
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# This method is called from a asynchronous handler so it's
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# better to exit from this quickly to allow other
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# asynchronous handlers to be executed.
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func = functools.partial(self._process_child, path=path)
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result = self._client.get_async(path)
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result.rawlink(func)
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def _format_job(self, job):
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posting = {
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'uuid': job.uuid,
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'name': job.name,
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}
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if job.details is not None:
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posting['details'] = job.details
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if job.book is not None:
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posting['book'] = {
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'name': job.book.name,
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'uuid': job.book.uuid,
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}
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return misc.binary_encode(jsonutils.dumps(posting))
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def post(self, name, book, details=None):
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# Didn't work, clean it up.
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def try_clean(path):
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with self._job_mutate:
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self._remove_job(path)
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# NOTE(harlowja): Jobs are not ephemeral, they will persist until they
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# are consumed (this may change later, but seems safer to do this until
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# further notice).
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job = ZookeeperJob(name, self,
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self._client, self._persistence,
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book=book, details=details)
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job_path, _lock_path = _get_paths(self.path, job.uuid)
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# NOTE(harlowja): This avoids the watcher thread from attempting to
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# overwrite or delete this job which is not yet ready but is in the
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# process of being posted.
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with self._job_mutate:
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self._known_jobs[job_path] = (job, _POSTING)
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with self._wrap(job.uuid, "Posting failure: %s", ensure_known=False):
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try:
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self._client.create(job_path, value=self._format_job(job))
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with self._job_mutate:
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self._known_jobs[job_path] = (job, _READY)
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return job
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except k_exceptions.NodeExistsException:
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try_clean()
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raise excp.JobAlreadyExists("Duplicate job %s already posted"
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% job.uuid)
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except Exception:
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with excutils.save_and_reraise_exception():
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try_clean()
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def claim(self, job, who):
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_check_who(who)
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job_path, lock_path = _get_paths(self.path, job.uuid)
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with self._wrap(job.uuid, "Claiming failure: %s"):
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# NOTE(harlowja): post as json which will allow for future changes
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# more easily than a raw string/text.
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value = jsonutils.dumps({
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'owner': who,
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})
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try:
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self._client.create(lock_path,
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value=misc.binary_encode(value),
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ephemeral=True)
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except k_exceptions.NodeExistsException:
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# Try to see if we can find who the owner really is...
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try:
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owner = self.find_owner(job)
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except Exception:
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owner = None
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if owner:
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msg = "Job %s already claimed by '%s'" % (job.uuid, owner)
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else:
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msg = "Job %s already claimed" % (job.uuid)
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raise excp.UnclaimableJob(msg)
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@contextlib.contextmanager
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def _wrap(self, job_uuid, fail_msg_tpl="Failure: %s", ensure_known=True):
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if ensure_known:
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job_path, _lock_path = _get_paths(self.path, job_uuid)
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with self._job_mutate:
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if job_path not in self._known_jobs:
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fail_msg_tpl += ", unknown job"
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raise excp.JobNotFound(fail_msg_tpl % (job_uuid))
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try:
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yield
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except self._client.handler.timeout_exception:
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fail_msg_tpl += ", connection timed out"
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raise excp.ConnectionFailure(fail_msg_tpl % (job_uuid))
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except k_exceptions.SessionExpiredError:
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fail_msg_tpl += ", session expired"
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raise excp.ConnectionFailure(fail_msg_tpl % (job_uuid))
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except k_exceptions.NoNodeError:
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fail_msg_tpl += ", unknown job"
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raise excp.JobNotFound(fail_msg_tpl % (job_uuid))
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except k_exceptions.KazooException as e:
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fail_msg_tpl += ", internal error: %s"
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raise excp.InvalidJobOperation(fail_msg_tpl % (job_uuid, e))
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def find_owner(self, job):
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_job_path, lock_path = _get_paths(self.path, job.uuid)
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with self._wrap(job.uuid, "Owner query failure: %s"):
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try:
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self._client.sync(lock_path)
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raw_data, _lock_stat = self._client.get(lock_path)
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data = misc.decode_json(raw_data)
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owner = data.get("owner")
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except k_exceptions.NoNodeError:
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owner = None
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return owner
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def _get_owner_and_data(self, job):
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job_path, lock_path = _get_paths(self.path, job.uuid)
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lock_data, lock_stat = self._client.get(lock_path)
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job_data, job_stat = self._client.get(job_path)
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return (misc.decode_json(lock_data), lock_stat,
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misc.decode_json(job_data), job_stat)
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def consume(self, job, who):
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_check_who(who)
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job_path, lock_path = _get_paths(self.path, job.uuid)
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with self._wrap(job.uuid, "Consumption failure: %s"):
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try:
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owner_data = self._get_owner_and_data(job)
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lock_data, lock_stat, data, data_stat = owner_data
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except k_exceptions.NoNodeError:
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raise excp.InvalidJobOperation("Can not consume a job %s"
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" which we can not determine"
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" the owner of" % (job.uuid))
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if lock_data.get("owner") != who:
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raise excp.InvalidJobOperation("Can not consume a job %s"
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" which is not owned by %s"
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% (job.uuid, who))
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with self._client.transaction() as txn:
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txn.delete(lock_path, version=lock_stat.version)
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txn.delete(job_path, version=data_stat.version)
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with self._job_mutate:
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self._remove_job(job_path)
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def abandon(self, job, who):
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_check_who(who)
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job_path, lock_path = _get_paths(self.path, job.uuid)
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with self._wrap(job.uuid, "Abandonment failure: %s"):
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try:
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owner_data = self._get_owner_and_data(job)
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lock_data, lock_stat, data, data_stat = owner_data
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except k_exceptions.NoNodeError:
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raise excp.InvalidJobOperation("Can not abandon a job %s"
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" which we can not determine"
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" the owner of" % (job.uuid))
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if lock_data.get("owner") != who:
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raise excp.InvalidJobOperation("Can not abandon a job %s"
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" which is not owned by %s"
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% (job.uuid, who))
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with self._client.transaction() as txn:
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txn.delete(lock_path, version=lock_stat.version)
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def _state_change_listener(self, state):
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LOG.debug("Kazoo client has changed to state: %s", state)
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def _clear(self):
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with self._job_mutate:
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self._known_jobs = {}
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self._job_watcher = None
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@property
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def connected(self):
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return self._client.connected
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@lock_utils.locked(lock='_open_close_lock')
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def close(self):
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if self._owned:
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LOG.debug("Stopping client")
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kazoo_utils.finalize_client(self._client)
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self._clear()
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LOG.debug("Stopped & cleared local state")
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@lock_utils.locked(lock='_open_close_lock')
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def connect(self, timeout=10.0):
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def try_clean():
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# Attempt to do the needed cleanup if post-connection setup does
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# not succeed (maybe the connection is lost right after it is
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# obtained).
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try:
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self.close()
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except k_exceptions.KazooException:
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LOG.exception("Failed cleaning-up after post-connection"
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" initialization failed")
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try:
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if timeout is not None:
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timeout = float(timeout)
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self._client.start(timeout=timeout)
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except (self._client.handler.timeout_exception,
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k_exceptions.KazooException) as e:
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raise excp.ConnectionFailure("Failed to connect to"
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" zookeeper due to: %s" % (e))
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try:
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kazoo_utils.check_compatible(self._client, MIN_ZK_VERSION)
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self._client.ensure_path(self.path)
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self._job_watcher = watchers.ChildrenWatch(
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self._client,
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self.path,
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func=self._on_job_posting,
|
|
allow_session_lost=False)
|
|
except excp.IncompatibleVersion:
|
|
with excutils.save_and_reraise_exception():
|
|
try_clean()
|
|
except (self._client.handler.timeout_exception,
|
|
k_exceptions.KazooException) as e:
|
|
try_clean()
|
|
raise excp.ConnectionFailure("Failed to do post-connection"
|
|
" initialization due to: %s" % (e))
|