1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
|
# -*- coding: utf-8 -*-
# Copyright (C) 2013 Rackspace Hosting Inc. All Rights Reserved.
# 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 abc
import collections
import contextlib
import functools
import time
import enum
from oslo_utils import timeutils
from oslo_utils import uuidutils
from taskflow import exceptions as excp
from taskflow import states
from taskflow.types import notifier
from taskflow.utils import iter_utils
class JobPriority(enum.Enum):
"""Enum of job priorities (modeled after hadoop job priorities)."""
#: Extremely urgent job priority.
VERY_HIGH = 'VERY_HIGH'
#: Mildly urgent job priority.
HIGH = 'HIGH'
#: Default job priority.
NORMAL = 'NORMAL'
#: Not needed anytime soon job priority.
LOW = 'LOW'
#: Very much not needed anytime soon job priority.
VERY_LOW = 'VERY_LOW'
@classmethod
def convert(cls, value):
if isinstance(value, cls):
return value
try:
return cls(value.upper())
except (ValueError, AttributeError):
valids = [cls.VERY_HIGH, cls.HIGH, cls.NORMAL,
cls.LOW, cls.VERY_LOW]
valids = [p.value for p in valids]
raise ValueError("'%s' is not a valid priority, valid"
" priorities are %s" % (value, valids))
@classmethod
def reorder(cls, *values):
"""Reorders (priority, value) tuples -> priority ordered values."""
if len(values) == 0:
raise ValueError("At least one (priority, value) pair is"
" required")
elif len(values) == 1:
v1 = values[0]
# Even though this isn't used, we do the conversion because
# all the other branches in this function do it so we do it
# to be consistent (this also will raise on bad values, which
# we want to do)...
p1 = cls.convert(v1[0])
return v1[1]
else:
# Order very very much matters in this tuple...
priority_ordering = (cls.VERY_HIGH, cls.HIGH,
cls.NORMAL, cls.LOW, cls.VERY_LOW)
if len(values) == 2:
# It's common to use this in a 2 tuple situation, so
# make it avoid all the needed complexity that is done
# for greater than 2 tuples.
v1 = values[0]
v2 = values[1]
p1 = cls.convert(v1[0])
p2 = cls.convert(v2[0])
p1_i = priority_ordering.index(p1)
p2_i = priority_ordering.index(p2)
if p1_i <= p2_i:
return v1[1], v2[1]
else:
return v2[1], v1[1]
else:
buckets = collections.defaultdict(list)
for (p, v) in values:
p = cls.convert(p)
buckets[p].append(v)
values = []
for p in priority_ordering:
values.extend(buckets[p])
return tuple(values)
class Job(object, metaclass=abc.ABCMeta):
"""A abstraction that represents a named and trackable unit of work.
A job connects a logbook, a owner, a priority, last modified and created
on dates and any associated state that the job has. Since it is a connected
to a logbook, which are each associated with a set of factories that can
create set of flows, it is the current top-level container for a piece of
work that can be owned by an entity (typically that entity will read those
logbooks and run any contained flows).
Only one entity will be allowed to own and operate on the flows contained
in a job at a given time (for the foreseeable future).
NOTE(harlowja): It is the object that will be transferred to another
entity on failure so that the contained flows ownership can be
transferred to the secondary entity/owner for resumption, continuation,
reverting...
"""
def __init__(self, board, name,
uuid=None, details=None, backend=None,
book=None, book_data=None):
if uuid:
self._uuid = uuid
else:
self._uuid = uuidutils.generate_uuid()
self._name = name
if not details:
details = {}
self._details = details
self._backend = backend
self._board = board
self._book = book
if not book_data:
book_data = {}
self._book_data = book_data
@abc.abstractproperty
def last_modified(self):
"""The datetime the job was last modified."""
@abc.abstractproperty
def created_on(self):
"""The datetime the job was created on."""
@property
def board(self):
"""The board this job was posted on or was created from."""
return self._board
@abc.abstractproperty
def state(self):
"""Access the current state of this job."""
@abc.abstractproperty
def priority(self):
"""The :py:class:`~.JobPriority` of this job."""
def wait(self, timeout=None,
delay=0.01, delay_multiplier=2.0, max_delay=60.0,
sleep_func=time.sleep):
"""Wait for job to enter completion state.
If the job has not completed in the given timeout, then return false,
otherwise return true (a job failure exception may also be raised if
the job information can not be read, for whatever reason). Periodic
state checks will happen every ``delay`` seconds where ``delay`` will
be multiplied by the given multipler after a state is found that is
**not** complete.
Note that if no timeout is given this is equivalent to blocking
until the job has completed. Also note that if a jobboard backend
can optimize this method then its implementation may not use
delays (and backoffs) at all. In general though no matter what
optimizations are applied implementations must **always** respect
the given timeout value.
"""
if timeout is not None:
w = timeutils.StopWatch(duration=timeout)
w.start()
else:
w = None
delay_gen = iter_utils.generate_delays(delay, max_delay,
multiplier=delay_multiplier)
while True:
if w is not None and w.expired():
return False
if self.state == states.COMPLETE:
return True
sleepy_secs = next(delay_gen)
if w is not None:
sleepy_secs = min(w.leftover(), sleepy_secs)
sleep_func(sleepy_secs)
return False
@property
def book(self):
"""Logbook associated with this job.
If no logbook is associated with this job, this property is None.
"""
if self._book is None:
self._book = self._load_book()
return self._book
@property
def book_uuid(self):
"""UUID of logbook associated with this job.
If no logbook is associated with this job, this property is None.
"""
if self._book is not None:
return self._book.uuid
else:
return self._book_data.get('uuid')
@property
def book_name(self):
"""Name of logbook associated with this job.
If no logbook is associated with this job, this property is None.
"""
if self._book is not None:
return self._book.name
else:
return self._book_data.get('name')
@property
def uuid(self):
"""The uuid of this job."""
return self._uuid
@property
def details(self):
"""A dictionary of any details associated with this job."""
return self._details
@property
def name(self):
"""The non-uniquely identifying name of this job."""
return self._name
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
def __str__(self):
"""Pretty formats the job into something *more* meaningful."""
cls_name = type(self).__name__
return "%s: %s (priority=%s, uuid=%s, details=%s)" % (
cls_name, self.name, self.priority,
self.uuid, self.details)
class JobBoardIterator(object):
"""Iterator over a jobboard that iterates over potential jobs.
It provides the following attributes:
* ``only_unclaimed``: boolean that indicates whether to only iterate
over unclaimed jobs
* ``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)
* ``board``: the board this iterator was created from
"""
_UNCLAIMED_JOB_STATES = (states.UNCLAIMED,)
_JOB_STATES = (states.UNCLAIMED, states.COMPLETE, states.CLAIMED)
def __init__(self, board, logger,
board_fetch_func=None, board_removal_func=None,
only_unclaimed=False, ensure_fresh=False):
self._board = board
self._logger = logger
self._board_removal_func = board_removal_func
self._board_fetch_func = board_fetch_func
self._fetched = False
self._jobs = collections.deque()
self.only_unclaimed = only_unclaimed
self.ensure_fresh = ensure_fresh
@property
def board(self):
"""The board this iterator was created from."""
return self._board
def __iter__(self):
return self
def _next_job(self):
if self.only_unclaimed:
allowed_states = self._UNCLAIMED_JOB_STATES
else:
allowed_states = self._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:
self._logger.warn("Failed determining the state of"
" job '%s'", maybe_job, exc_info=True)
except excp.NotFound:
# Attempt to clean this off the board now that we found
# it wasn't really there (this **must** gracefully handle
# removal already having happened).
if self._board_removal_func is not None:
self._board_removal_func(maybe_job)
return job
def __next__(self):
if not self._jobs:
if not self._fetched:
if self._board_fetch_func is not None:
self._jobs.extend(
self._board_fetch_func(
ensure_fresh=self.ensure_fresh))
self._fetched = True
job = self._next_job()
if job is None:
raise StopIteration
else:
return job
class JobBoard(object, metaclass=abc.ABCMeta):
"""A place where jobs can be posted, reposted, claimed and transferred.
There can be multiple implementations of this job board, depending on the
desired semantics and capabilities of the underlying jobboard
implementation.
NOTE(harlowja): the name is meant to be an analogous to a board/posting
system that is used in newspapers, or elsewhere to solicit jobs that
people can interview and apply for (and then work on & complete).
"""
def __init__(self, name, conf):
self._name = name
self._conf = conf
@abc.abstractmethod
def iterjobs(self, only_unclaimed=False, ensure_fresh=False):
"""Returns an iterator of jobs that are currently on this board.
NOTE(harlowja): the ordering of this iteration should be by posting
order (oldest to newest) with higher priority jobs
being provided before lower priority jobs, but it is left up to the
backing implementation to provide the order that best suits it..
NOTE(harlowja): the iterator that is returned may support other
attributes which can be used to further customize how iteration can
be accomplished; check with the backends iterator object to determine
what other attributes are supported.
:param only_unclaimed: boolean that indicates whether to only iteration
over unclaimed jobs.
:param ensure_fresh: boolean that requests to only iterate over the
most recent jobs available, where the definition of what is recent
is backend specific. It is allowable that a backend may ignore this
value if the backends internal semantics/capabilities can not
support this argument.
"""
@abc.abstractmethod
def wait(self, timeout=None):
"""Waits a given amount of time for **any** jobs to be posted.
When jobs are found then an iterator will be returned that can be used
to iterate over those jobs.
NOTE(harlowja): since a jobboard can be mutated on by multiple external
entities at the **same** time the iterator that can be
returned **may** still be empty due to other entities removing those
jobs after the iterator has been created (be aware of this when
using it).
:param timeout: float that indicates how long to wait for a job to
appear (if None then waits forever).
"""
@abc.abstractproperty
def job_count(self):
"""Returns how many jobs are on this jobboard.
NOTE(harlowja): this count may change as jobs appear or are removed so
the accuracy of this count should not be used in a way that requires
it to be exact & absolute.
"""
@abc.abstractmethod
def find_owner(self, job):
"""Gets the owner of the job if one exists."""
@property
def name(self):
"""The non-uniquely identifying name of this jobboard."""
return self._name
@abc.abstractmethod
def consume(self, job, who):
"""Permanently (and atomically) removes a job from the jobboard.
Consumption signals to the board (and any others examining the board)
that this job has been completed by the entity that previously claimed
that job.
Only the entity that has claimed that job is able to consume the job.
A job that has been consumed can not be reclaimed or reposted by
another entity (job postings are immutable). Any entity consuming
a unclaimed job (or a job they do not have a claim on) will cause an
exception.
:param job: a job on this jobboard that can be consumed (if it does
not exist then a NotFound exception will be raised).
:param who: string that names the entity performing the consumption,
this must be the same name that was used for claiming this job.
"""
@abc.abstractmethod
def post(self, name, book=None, details=None, priority=JobPriority.NORMAL):
"""Atomically creates and posts a job to the jobboard.
This posting allowing others to attempt to claim that job (and
subsequently work on that job). The contents of the provided logbook,
details dictionary, or name (or a mix of these) must provide *enough*
information for consumers to reference to construct and perform that
jobs contained work (whatever it may be).
Once a job has been posted it can only be removed by consuming that
job (after that job is claimed). Any entity can post/propose jobs
to the jobboard (in the future this may be restricted).
Returns a job object representing the information that was posted.
"""
@abc.abstractmethod
def claim(self, job, who):
"""Atomically attempts to claim the provided job.
If a job is claimed it is expected that the entity that claims that job
will at sometime in the future work on that jobs contents and either
fail at completing them (resulting in a reposting) or consume that job
from the jobboard (signaling its completion). If claiming fails then
a corresponding exception will be raised to signal this to the claim
attempter.
:param job: a job on this jobboard that can be claimed (if it does
not exist then a NotFound exception will be raised).
:param who: string that names the claiming entity.
"""
@abc.abstractmethod
def abandon(self, job, who):
"""Atomically attempts to abandon the provided job.
This abandonment signals to others that the job may now be reclaimed.
This would typically occur if the entity that has claimed the job has
failed or is unable to complete the job or jobs it had previously
claimed.
Only the entity that has claimed that job can abandon a job. Any entity
abandoning a unclaimed job (or a job they do not own) will cause an
exception.
:param job: a job on this jobboard that can be abandoned (if it does
not exist then a NotFound exception will be raised).
:param who: string that names the entity performing the abandoning,
this must be the same name that was used for claiming this job.
"""
@abc.abstractmethod
def trash(self, job, who):
"""Trash the provided job.
Trashing a job signals to others that the job is broken and should not
be reclaimed. This is provided as an option for users to be able to
remove jobs from the board externally. The trashed job details should
be kept around in an alternate location to be reviewed, if desired.
Only the entity that has claimed that job can trash a job. Any entity
trashing a unclaimed job (or a job they do not own) will cause an
exception.
:param job: a job on this jobboard that can be trashed (if it does
not exist then a NotFound exception will be raised).
:param who: string that names the entity performing the trashing,
this must be the same name that was used for claiming this job.
"""
@abc.abstractmethod
def register_entity(self, entity):
"""Register an entity to the jobboard('s backend), e.g: a conductor.
:param entity: entity to register as being associated with the
jobboard('s backend)
:type entity: :py:class:`~taskflow.types.entity.Entity`
"""
@abc.abstractproperty
def connected(self):
"""Returns if this jobboard is connected."""
@abc.abstractmethod
def connect(self):
"""Opens the connection to any backend system."""
@abc.abstractmethod
def close(self):
"""Close the connection to any backend system.
Once closed the jobboard can no longer be used (unless reconnection
occurs).
"""
# Jobboard events
POSTED = 'POSTED' # new job is/has been posted
REMOVAL = 'REMOVAL' # existing job is/has been removed
class NotifyingJobBoard(JobBoard):
"""A jobboard subclass that can notify others about board events.
Implementers are expected to notify *at least* about jobs being posted
and removed.
NOTE(harlowja): notifications that are emitted *may* be emitted on a
separate dedicated thread when they occur, so ensure that all callbacks
registered are thread safe (and block for as little time as possible).
"""
def __init__(self, name, conf):
super(NotifyingJobBoard, self).__init__(name, conf)
self.notifier = notifier.Notifier()
# Internal helpers for usage by board implementations...
def check_who(meth):
@functools.wraps(meth)
def wrapper(self, job, who, *args, **kwargs):
if not isinstance(who, str):
raise TypeError("Job applicant must be a string type")
if len(who) == 0:
raise ValueError("Job applicant must be non-empty")
return meth(self, job, who, *args, **kwargs)
return wrapper
def format_posting(uuid, name, created_on=None, last_modified=None,
details=None, book=None, priority=JobPriority.NORMAL):
posting = {
'uuid': uuid,
'name': name,
'priority': priority.value,
}
if created_on is not None:
posting['created_on'] = created_on
if last_modified is not None:
posting['last_modified'] = last_modified
if details:
posting['details'] = details
else:
posting['details'] = {}
if book is not None:
posting['book'] = {
'name': book.name,
'uuid': book.uuid,
}
return posting
|