Files
deb-python-taskflow/taskflow/jobs/backends/impl_zookeeper.py

672 lines
26 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
#
# 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 collections
import contextlib
import functools
import logging
import threading
from concurrent import futures
from kazoo import exceptions as k_exceptions
from kazoo.protocol import paths as k_paths
from kazoo.recipe import watchers
import six
from taskflow import exceptions as excp
from taskflow.jobs import job as base_job
from taskflow.jobs import jobboard
from taskflow.openstack.common import excutils
from taskflow.openstack.common import jsonutils
from taskflow.openstack.common import uuidutils
from taskflow import states
from taskflow.types import timing as tt
from taskflow.utils import kazoo_utils
from taskflow.utils import lock_utils
from taskflow.utils import misc
LOG = logging.getLogger(__name__)
UNCLAIMED_JOB_STATES = (
states.UNCLAIMED,
)
ALL_JOB_STATES = (
states.UNCLAIMED,
states.COMPLETE,
states.CLAIMED,
)
# Transaction support was added in 3.4.0
MIN_ZK_VERSION = (3, 4, 0)
LOCK_POSTFIX = ".lock"
JOB_PREFIX = 'job'
def _check_who(who):
if not isinstance(who, six.string_types):
raise TypeError("Job applicant must be a string type")
if len(who) == 0:
raise ValueError("Job applicant must be non-empty")
class ZookeeperJob(base_job.Job):
def __init__(self, name, board, client, backend, path,
uuid=None, details=None, book=None, book_data=None,
created_on=None):
super(ZookeeperJob, self).__init__(name, uuid=uuid, details=details)
self._board = board
self._book = book
if not book_data:
book_data = {}
self._book_data = book_data
self._client = client
self._backend = backend
if all((self._book, self._book_data)):
raise ValueError("Only one of 'book_data' or 'book'"
" can be provided")
self._path = path
self._lock_path = path + LOCK_POSTFIX
self._created_on = created_on
self._node_not_found = False
@property
def lock_path(self):
return self._lock_path
@property
def path(self):
return self._path
def _get_node_attr(self, path, attr_name, trans_func=None):
try:
_data, node_stat = self._client.get(path)
attr = getattr(node_stat, attr_name)
if trans_func is not None:
return trans_func(attr)
else:
return attr
except k_exceptions.NoNodeError as e:
raise excp.NotFound("Can not fetch the %r attribute"
" of job %s (%s), path %s not found"
% (attr_name, self.uuid, self.path, path), e)
except self._client.handler.timeout_exception as e:
raise excp.JobFailure("Can not fetch the %r attribute"
" of job %s (%s), connection timed out"
% (attr_name, self.uuid, self.path), e)
except k_exceptions.SessionExpiredError as e:
raise excp.JobFailure("Can not fetch the %r attribute"
" of job %s (%s), session expired"
% (attr_name, self.uuid, self.path), e)
except (AttributeError, k_exceptions.KazooException) as e:
raise excp.JobFailure("Can not fetch the %r attribute"
" of job %s (%s), internal error" %
(attr_name, self.uuid, self.path), e)
@property
def last_modified(self):
modified_on = None
try:
if not self._node_not_found:
modified_on = self._get_node_attr(
self.path, 'mtime',
trans_func=misc.millis_to_datetime)
except excp.NotFound:
self._node_not_found = True
return modified_on
@property
def created_on(self):
# This one we can cache (since it won't change after creation).
if self._node_not_found:
return None
if self._created_on is None:
try:
self._created_on = self._get_node_attr(
self.path, 'ctime',
trans_func=misc.millis_to_datetime)
except excp.NotFound:
self._node_not_found = True
return self._created_on
@property
def board(self):
return self._board
def _load_book(self):
book_uuid = self.book_uuid
if self._backend is not None and book_uuid is not None:
# TODO(harlowja): we are currently limited by assuming that the
# job posted has the same backend as this loader (to start this
# seems to be a ok assumption, and can be adjusted in the future
# if we determine there is a use-case for multi-backend loaders,
# aka a registry of loaders).
with contextlib.closing(self._backend.get_connection()) as conn:
return conn.get_logbook(book_uuid)
# No backend to fetch from or no uuid specified
return None
@property
def state(self):
owner = self.board.find_owner(self)
job_data = {}
try:
raw_data, _data_stat = self._client.get(self.path)
job_data = misc.decode_json(raw_data)
except k_exceptions.NoNodeError:
pass
except k_exceptions.SessionExpiredError as e:
raise excp.JobFailure("Can not fetch the state of %s,"
" session expired" % (self.uuid), e)
except self._client.handler.timeout_exception as e:
raise excp.JobFailure("Can not fetch the state of %s,"
" connection timed out" % (self.uuid), e)
except k_exceptions.KazooException as e:
raise excp.JobFailure("Can not fetch the state of %s, internal"
" error" % (self.uuid), e)
if not job_data:
# No data this job has been completed (the owner that we might have
# fetched will not be able to be fetched again, since the job node
# is a parent node of the owner/lock node).
return states.COMPLETE
if not owner:
# No owner, but data, still work to be done.
return states.UNCLAIMED
return states.CLAIMED
def __cmp__(self, other):
return cmp(self.path, other.path)
def __hash__(self):
return hash(self.path)
@property
def book(self):
if self._book is None:
self._book = self._load_book()
return self._book
@property
def book_uuid(self):
if self._book:
return self._book.uuid
if self._book_data:
return self._book_data.get('uuid')
else:
return None
@property
def book_name(self):
if self._book:
return self._book.name
if self._book_data:
return self._book_data.get('name')
else:
return None
class ZookeeperJobBoardIterator(six.Iterator):
"""Iterator over a zookeeper jobboard.
It supports the following attributes/constructor arguments:
* ensure_fresh: boolean that requests that during every fetch of a new
set of jobs this will cause the iterator to force the backend to
refresh (ensuring that the jobboard has the most recent job listings).
* only_unclaimed: boolean that indicates whether to only iterate
over unclaimed jobs.
"""
def __init__(self, board, only_unclaimed=False, ensure_fresh=False):
self._board = board
self._jobs = collections.deque()
self._fetched = False
self.ensure_fresh = ensure_fresh
self.only_unclaimed = only_unclaimed
@property
def board(self):
return self._board
def __iter__(self):
return self
def _next_job(self):
if self.only_unclaimed:
allowed_states = UNCLAIMED_JOB_STATES
else:
allowed_states = ALL_JOB_STATES
job = None
while self._jobs and job is None:
maybe_job = self._jobs.popleft()
try:
if maybe_job.state in allowed_states:
job = maybe_job
except excp.JobFailure:
LOG.warn("Failed determining the state of job: %s (%s)",
maybe_job.uuid, maybe_job.path, exc_info=True)
except excp.NotFound:
self._board._remove_job(maybe_job.path)
return job
def __next__(self):
if not self._jobs:
if not self._fetched:
jobs = self._board._fetch_jobs(ensure_fresh=self.ensure_fresh)
self._jobs.extend(jobs)
self._fetched = True
job = self._next_job()
if job is None:
raise StopIteration
else:
return job
class ZookeeperJobBoard(jobboard.NotifyingJobBoard):
def __init__(self, name, conf,
client=None, persistence=None, emit_notifications=True):
super(ZookeeperJobBoard, self).__init__(name, conf)
if client is not None:
self._client = client
self._owned = False
else:
self._client = kazoo_utils.make_client(self._conf)
self._owned = True
path = str(conf.get("path", "/taskflow/jobs"))
if not path:
raise ValueError("Empty zookeeper path is disallowed")
if not k_paths.isabs(path):
raise ValueError("Zookeeper path must be absolute")
self._path = path
# The backend to load the full logbooks from, since whats sent over
# the zookeeper data connection is only the logbook uuid and name, and
# not currently the full logbook (later when a zookeeper backend
# appears we can likely optimize for that backend usage by directly
# reading from the path where the data is stored, if we want).
self._persistence = persistence
# Misc. internal details
self._known_jobs = {}
self._job_lock = threading.RLock()
self._job_cond = threading.Condition(self._job_lock)
self._open_close_lock = threading.RLock()
self._client.add_listener(self._state_change_listener)
self._bad_paths = frozenset([path])
self._job_watcher = None
# Since we use sequenced ids this will be the path that the sequences
# are prefixed with, for example, job0000000001, job0000000002, ...
self._job_base = k_paths.join(path, JOB_PREFIX)
self._worker = None
self._emit_notifications = bool(emit_notifications)
def _emit(self, state, details):
# Submit the work to the executor to avoid blocking the kazoo queue.
if self._worker is not None:
self._worker.submit(self.notifier.notify, state, details)
@property
def path(self):
return self._path
@property
def job_count(self):
with self._job_lock:
return len(self._known_jobs)
def _fetch_jobs(self, ensure_fresh=False):
if ensure_fresh:
self._force_refresh()
with self._job_lock:
return sorted(six.itervalues(self._known_jobs))
def _force_refresh(self):
try:
children = self._client.get_children(self.path)
except self._client.handler.timeout_exception as e:
raise excp.JobFailure("Refreshing failure, connection timed out",
e)
except k_exceptions.SessionExpiredError as e:
raise excp.JobFailure("Refreshing failure, session expired", e)
except k_exceptions.NoNodeError:
pass
except k_exceptions.KazooException as e:
raise excp.JobFailure("Refreshing failure, internal error", e)
else:
self._on_job_posting(children, delayed=False)
def iterjobs(self, only_unclaimed=False, ensure_fresh=False):
return ZookeeperJobBoardIterator(self,
only_unclaimed=only_unclaimed,
ensure_fresh=ensure_fresh)
def _remove_job(self, path):
LOG.debug("Removing job that was at path: %s", path)
with self._job_lock:
job = self._known_jobs.pop(path, None)
if job is not None:
self._emit(jobboard.REMOVAL, details={'job': job})
def _process_child(self, path, request):
"""Receives the result of a child data fetch request."""
job = None
try:
raw_data, node_stat = request.get()
job_data = misc.decode_json(raw_data)
created_on = misc.millis_to_datetime(node_stat.ctime)
except (ValueError, TypeError, KeyError):
LOG.warn("Incorrectly formatted job data found at path: %s",
path, exc_info=True)
except self._client.handler.timeout_exception:
LOG.warn("Connection timed out fetching job data from path: %s",
path, exc_info=True)
except k_exceptions.SessionExpiredError:
LOG.warn("Session expired fetching job data from path: %s", path,
exc_info=True)
except k_exceptions.NoNodeError:
LOG.debug("No job node found at path: %s, it must have"
" disappeared or was removed", path)
except k_exceptions.KazooException:
LOG.warn("Internal error fetching job data from path: %s",
path, exc_info=True)
else:
self._job_cond.acquire()
try:
if path not in self._known_jobs:
job = ZookeeperJob(job_data['name'], self,
self._client, self._persistence, path,
uuid=job_data['uuid'],
book_data=job_data.get("book"),
details=job_data.get("details", {}),
created_on=created_on)
self._known_jobs[path] = job
self._job_cond.notify_all()
finally:
self._job_cond.release()
if job is not None:
self._emit(jobboard.POSTED, details={'job': job})
def _on_job_posting(self, children, delayed=True):
LOG.debug("Got children %s under path %s", children, self.path)
child_paths = []
for c in children:
if c.endswith(LOCK_POSTFIX) or not c.startswith(JOB_PREFIX):
# Skip lock paths or non-job-paths (these are not valid jobs)
continue
child_paths.append(k_paths.join(self.path, c))
# Remove jobs that we know about but which are no longer children
with self._job_lock:
removals = set()
for path, _job in six.iteritems(self._known_jobs):
if path not in child_paths:
removals.add(path)
for path in removals:
self._remove_job(path)
# Ensure that we have a job record for each new job that has appeared
for path in child_paths:
if path in self._bad_paths:
continue
with self._job_lock:
if path not in self._known_jobs:
# Fire off the request to populate this job asynchronously.
#
# This method is *usually* called from a asynchronous
# handler so it's better to exit from this quickly to
# allow other asynchronous handlers to be executed.
request = self._client.get_async(path)
child_proc = functools.partial(self._process_child, path)
if delayed:
request.rawlink(child_proc)
else:
child_proc(request)
def post(self, name, book=None, details=None):
def format_posting(job_uuid):
posting = {
'uuid': job_uuid,
'name': name,
}
if details:
posting['details'] = details
else:
posting['details'] = {}
if book is not None:
posting['book'] = {
'name': book.name,
'uuid': book.uuid,
}
return posting
# NOTE(harlowja): Jobs are not ephemeral, they will persist until they
# are consumed (this may change later, but seems safer to do this until
# further notice).
job_uuid = uuidutils.generate_uuid()
with self._wrap(job_uuid, None,
"Posting failure: %s", ensure_known=False):
job_posting = format_posting(job_uuid)
job_posting = misc.binary_encode(jsonutils.dumps(job_posting))
job_path = self._client.create(self._job_base,
value=job_posting,
sequence=True,
ephemeral=False)
job = ZookeeperJob(name, self, self._client,
self._persistence, job_path,
book=book, details=details,
uuid=job_uuid)
self._job_cond.acquire()
try:
self._known_jobs[job_path] = job
self._job_cond.notify_all()
finally:
self._job_cond.release()
self._emit(jobboard.POSTED, details={'job': job})
return job
def claim(self, job, who):
_check_who(who)
with self._wrap(job.uuid, job.path, "Claiming failure: %s"):
# NOTE(harlowja): post as json which will allow for future changes
# more easily than a raw string/text.
value = jsonutils.dumps({
'owner': who,
})
try:
self._client.create(job.lock_path,
value=misc.binary_encode(value),
ephemeral=True)
except k_exceptions.NodeExistsException:
# Try to see if we can find who the owner really is...
try:
owner = self.find_owner(job)
except Exception:
owner = None
if owner:
msg = "Job %s already claimed by '%s'" % (job.uuid, owner)
else:
msg = "Job %s already claimed" % (job.uuid)
raise excp.UnclaimableJob(msg)
@contextlib.contextmanager
def _wrap(self, job_uuid, job_path,
fail_msg_tpl="Failure: %s", ensure_known=True):
if job_path:
fail_msg_tpl += " (%s)" % (job_path)
if ensure_known:
if not job_path:
raise ValueError("Unable to check if %r is a known path"
% (job_path))
with self._job_lock:
if job_path not in self._known_jobs:
fail_msg_tpl += ", unknown job"
raise excp.NotFound(fail_msg_tpl % (job_uuid))
try:
yield
except self._client.handler.timeout_exception as e:
fail_msg_tpl += ", connection timed out"
raise excp.JobFailure(fail_msg_tpl % (job_uuid), e)
except k_exceptions.SessionExpiredError as e:
fail_msg_tpl += ", session expired"
raise excp.JobFailure(fail_msg_tpl % (job_uuid), e)
except k_exceptions.NoNodeError:
fail_msg_tpl += ", unknown job"
raise excp.NotFound(fail_msg_tpl % (job_uuid))
except k_exceptions.KazooException as e:
fail_msg_tpl += ", internal error"
raise excp.JobFailure(fail_msg_tpl % (job_uuid), e)
def find_owner(self, job):
with self._wrap(job.uuid, job.path, "Owner query failure: %s"):
try:
self._client.sync(job.lock_path)
raw_data, _lock_stat = self._client.get(job.lock_path)
data = misc.decode_json(raw_data)
owner = data.get("owner")
except k_exceptions.NoNodeError:
owner = None
return owner
def _get_owner_and_data(self, job):
lock_data, lock_stat = self._client.get(job.lock_path)
job_data, job_stat = self._client.get(job.path)
return (misc.decode_json(lock_data), lock_stat,
misc.decode_json(job_data), job_stat)
def consume(self, job, who):
_check_who(who)
with self._wrap(job.uuid, job.path, "Consumption failure: %s"):
try:
owner_data = self._get_owner_and_data(job)
lock_data, lock_stat, data, data_stat = owner_data
except k_exceptions.NoNodeError:
raise excp.JobFailure("Can not consume a job %s"
" which we can not determine"
" the owner of" % (job.uuid))
if lock_data.get("owner") != who:
raise excp.JobFailure("Can not consume a job %s"
" which is not owned by %s"
% (job.uuid, who))
with self._client.transaction() as txn:
txn.delete(job.lock_path, version=lock_stat.version)
txn.delete(job.path, version=data_stat.version)
self._remove_job(job.path)
def abandon(self, job, who):
_check_who(who)
with self._wrap(job.uuid, job.path, "Abandonment failure: %s"):
try:
owner_data = self._get_owner_and_data(job)
lock_data, lock_stat, data, data_stat = owner_data
except k_exceptions.NoNodeError:
raise excp.JobFailure("Can not abandon a job %s"
" which we can not determine"
" the owner of" % (job.uuid))
if lock_data.get("owner") != who:
raise excp.JobFailure("Can not abandon a job %s"
" which is not owned by %s"
% (job.uuid, who))
with self._client.transaction() as txn:
txn.delete(job.lock_path, version=lock_stat.version)
def _state_change_listener(self, state):
LOG.debug("Kazoo client has changed to state: %s", state)
def wait(self, timeout=None):
# Wait until timeout expires (or forever) for jobs to appear.
watch = None
if timeout is not None:
watch = tt.StopWatch(duration=float(timeout)).start()
self._job_cond.acquire()
try:
while True:
if not self._known_jobs:
if watch is not None and watch.expired():
raise excp.NotFound("Expired waiting for jobs to"
" arrive; waited %s seconds"
% watch.elapsed())
# This is done since the given timeout can not be provided
# to the condition variable, since we can not ensure that
# when we acquire the condition that there will actually
# be jobs (especially if we are spuriously awaken), so we
# must recalculate the amount of time we really have left.
timeout = None
if watch is not None:
timeout = watch.leftover()
self._job_cond.wait(timeout)
else:
it = ZookeeperJobBoardIterator(self)
it._jobs.extend(self._fetch_jobs())
it._fetched = True
return it
finally:
self._job_cond.release()
@property
def connected(self):
return self._client.connected
@lock_utils.locked(lock='_open_close_lock')
def close(self):
if self._owned:
LOG.debug("Stopping client")
kazoo_utils.finalize_client(self._client)
if self._worker is not None:
LOG.debug("Shutting down the notifier")
self._worker.shutdown()
self._worker = None
with self._job_lock:
self._known_jobs.clear()
LOG.debug("Stopped & cleared local state")
@lock_utils.locked(lock='_open_close_lock')
def connect(self, timeout=10.0):
def try_clean():
# Attempt to do the needed cleanup if post-connection setup does
# not succeed (maybe the connection is lost right after it is
# obtained).
try:
self.close()
except k_exceptions.KazooException:
LOG.exception("Failed cleaning-up after post-connection"
" initialization failed")
try:
if timeout is not None:
timeout = float(timeout)
self._client.start(timeout=timeout)
except (self._client.handler.timeout_exception,
k_exceptions.KazooException) as e:
raise excp.JobFailure("Failed to connect to zookeeper", e)
try:
kazoo_utils.check_compatible(self._client, MIN_ZK_VERSION)
if self._worker is None and self._emit_notifications:
self._worker = futures.ThreadPoolExecutor(max_workers=1)
self._client.ensure_path(self.path)
if self._job_watcher is None:
self._job_watcher = watchers.ChildrenWatch(
self._client,
self.path,
func=self._on_job_posting,
allow_session_lost=True)
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.JobFailure("Failed to do post-connection"
" initialization", e)