/usr/lib/python3/dist-packages/oslo_db/sqlalchemy/enginefacade.py is in python3-oslo.db 4.33.0-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 | # 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 contextlib
import functools
import operator
import threading
import warnings
import debtcollector.removals
import debtcollector.renames
from oslo_config import cfg
from oslo_utils import excutils
from oslo_db import exception
from oslo_db import options
from oslo_db.sqlalchemy import engines
from oslo_db.sqlalchemy import orm
from oslo_db.sqlalchemy import utils
class _symbol(object):
"""represent a fixed symbol."""
__slots__ = 'name',
def __init__(self, name):
self.name = name
def __repr__(self):
return "symbol(%r)" % self.name
_ASYNC_READER = _symbol('ASYNC_READER')
"""Represent the transaction state of "async reader".
This state indicates that the transaction is a read-only and is
safe to use on an asynchronously updated slave database.
"""
_READER = _symbol('READER')
"""Represent the transaction state of "reader".
This state indicates that the transaction is a read-only and is
only safe to use on a synchronously updated slave database; otherwise
the master database should be used.
"""
_WRITER = _symbol('WRITER')
"""Represent the transaction state of "writer".
This state indicates that the transaction writes data and
should be directed at the master database.
"""
class _Default(object):
"""Mark a value as a default value.
A value in the local configuration dictionary wrapped with
_Default() will not take precedence over a value that is specified
in cfg.CONF. Values that are set after the fact using configure()
will supersede those in cfg.CONF.
"""
__slots__ = 'value',
_notset = _symbol("NOTSET")
def __init__(self, value=_notset):
self.value = value
@classmethod
def resolve(cls, value):
if isinstance(value, _Default):
v = value.value
if v is cls._notset:
return None
else:
return v
else:
return value
@classmethod
def resolve_w_conf(cls, value, conf_namespace, key):
if isinstance(value, _Default):
v = getattr(conf_namespace, key, value.value)
if v is cls._notset:
return None
else:
return v
else:
return value
@classmethod
def is_set(cls, value):
return not isinstance(value, _Default) or \
value.value is not cls._notset
@classmethod
def is_set_w_conf(cls, value, conf_namespace, key):
return not isinstance(value, _Default) or \
value.value is not cls._notset or \
hasattr(conf_namespace, key)
class _TransactionFactory(object):
"""A factory for :class:`._TransactionContext` objects.
By default, there is just one of these, set up
based on CONF, however instance-level :class:`._TransactionFactory`
objects can be made, as is the case with the
:class:`._TestTransactionFactory` subclass used by the oslo.db test suite.
"""
def __init__(self):
self._url_cfg = {
'connection': _Default(),
'slave_connection': _Default(),
}
self._engine_cfg = {
'sqlite_fk': _Default(False),
'mysql_sql_mode': _Default('TRADITIONAL'),
'mysql_enable_ndb': _Default(False),
'connection_recycle_time': _Default(3600),
'connection_debug': _Default(0),
'max_pool_size': _Default(),
'max_overflow': _Default(),
'pool_timeout': _Default(),
'sqlite_synchronous': _Default(True),
'connection_trace': _Default(False),
'max_retries': _Default(10),
'retry_interval': _Default(10),
'thread_checkin': _Default(True),
'json_serializer': _Default(None),
'json_deserializer': _Default(None),
'logging_name': _Default(None)
}
self._maker_cfg = {
'expire_on_commit': _Default(False),
'__autocommit': True
}
self._transaction_ctx_cfg = {
'rollback_reader_sessions': False,
'flush_on_subtransaction': False,
}
self._facade_cfg = {
'synchronous_reader': True,
'on_engine_create': [],
}
# other options that are defined in oslo.db.options.database_opts
# but do not apply to the standard enginefacade arguments
# (most seem to apply to api.DBAPI).
self._ignored_cfg = dict(
(k, _Default(None)) for k in [
'db_max_retries', 'db_inc_retry_interval',
'use_db_reconnect',
'db_retry_interval', 'min_pool_size',
'db_max_retry_interval', 'backend'])
self._started = False
self._legacy_facade = None
self._start_lock = threading.Lock()
@debtcollector.renames.renamed_kwarg(
"idle_timeout", "connection_recycle_time", replace=True)
def configure_defaults(self, **kw):
"""Apply default configurational options.
This method can only be called before any specific
transaction-beginning methods have been called.
Configurational options are within a fixed set of keys, and fall
under three categories: URL configuration, engine configuration,
and session configuration. Each key given will be tested against
these three configuration sets to see which one is applicable; if
it is not applicable to any set, an exception is raised.
The configurational options given here act as **defaults**
when the :class:`._TransactionFactory` is configured using
a :class:`oslo_config.cfg.ConfigOpts` object; the options
present within the :class:`oslo_config.cfg.ConfigOpts` **take
precedence** versus the arguments passed here. By default,
the :class:`._TransactionFactory` loads in the configuration from
:data:`oslo_config.cfg.CONF`, after applying the
:data:`oslo_db.options.database_opts` configurational defaults to it.
:param connection: database URL
:param slave_connection: database URL
:param sqlite_fk: whether to enable SQLite foreign key pragma; default
False
:param mysql_sql_mode: MySQL SQL mode, defaults to TRADITIONAL
:param mysql_enable_ndb: enable MySQL Cluster (NDB) support
:param connection_recycle_time: connection pool recycle time,
defaults to 3600. Note the connection does not actually have to
be "idle" to be recycled.
:param connection_debug: engine logging level, defaults to 0. set to
50 for INFO, 100 for DEBUG.
:param max_pool_size: max size of connection pool, uses CONF for
default
:param max_overflow: max overflow for connection pool, uses CONF for
default
:param sqlite_synchronous: disable SQLite SYNCHRONOUS pragma if False;
defaults to True
:param connection_trace: enable tracing comments in logging
:param max_retries: max retries to connect, defaults to !0
:param retry_interval: time in seconds between retries, defaults to 10
:param thread_checkin: add sleep(0) on connection checkin to allow
greenlet yields, defaults to True
:param json_serializer: JSON serializer for PostgreSQL connections
:param json_deserializer: JSON deserializer for PostgreSQL connections
:param logging_name: logging name for engine
:param expire_on_commit: sets expire_on_commit for SQLAlchemy
sessionmaker; defaults to False
:param rollback_reader_sessions: if True, a :class:`.Session` object
will have its :meth:`.Session.rollback` method invoked at the end
of a ``@reader`` block, actively rolling back the transaction and
expiring the objects within, before the :class:`.Session` moves
on to be closed, which has the effect of releasing connection
resources back to the connection pool and detaching all objects.
If False, the :class:`.Session` is
not affected at the end of a ``@reader`` block; the underlying
connection referred to by this :class:`.Session` will still
be released in the enclosing context via the :meth:`.Session.close`
method, which still ensures that the DBAPI connection is rolled
back, however the objects associated with the :class:`.Session`
retain their database-persisted contents after they are detached.
.. seealso::
http://docs.sqlalchemy.org/en/rel_0_9/glossary.html#term-released\
SQLAlchemy documentation on what "releasing resources" means.
:param synchronous_reader: whether or not to assume a "reader" context
needs to guarantee it can read data committed by a "writer" assuming
replication lag is present; defaults to True. When False, a
@reader context works the same as @async_reader and will select
the "slave" database if present.
:param flush_on_subtransaction: if True, a :class:`.Session` object
will have its :meth:`.Session.flush` method invoked whenever a context
manager or decorator that is not itself the originator of the top-
level or savepoint :class:`.Session` transaction exits - in this way
it behaves like a "subtransaction" from a :class:`.Session`
perspective.
.. seealso::
:meth:`._TransactionFactory.configure`
"""
self._configure(True, kw)
@debtcollector.renames.renamed_kwarg(
"idle_timeout", "connection_recycle_time", replace=True)
def configure(self, **kw):
"""Apply configurational options.
This method can only be called before any specific
transaction-beginning methods have been called.
Behavior here is the same as that of
:meth:`._TransactionFactory.configure_defaults`,
with the exception that values specified here will **supersede** those
setup in the :class:`oslo_config.cfg.ConfigOpts` options. See
that method for a listing of all keyword arguments.
.. seealso::
:meth:`._TransactionFactory.configure_defaults`
"""
self._configure(False, kw)
def _configure(self, as_defaults, kw):
if self._started:
raise TypeError("this TransactionFactory is already started")
not_supported = []
for k, v in kw.items():
for dict_ in (
self._url_cfg, self._engine_cfg,
self._maker_cfg, self._ignored_cfg,
self._facade_cfg, self._transaction_ctx_cfg):
if k in dict_:
dict_[k] = _Default(v) if as_defaults else v
break
else:
not_supported.append(k)
if not_supported:
# would like to raise ValueError here, but there are just
# too many unrecognized (obsolete?) configuration options
# coming in from projects
warnings.warn(
"Configuration option(s) %r not supported" %
sorted(not_supported),
exception.NotSupportedWarning
)
def get_legacy_facade(self):
"""Return a :class:`.LegacyEngineFacade` for this factory.
This facade will make use of the same engine and sessionmaker
as this factory, however will not share the same transaction context;
the legacy facade continues to work the old way of returning
a new Session each time get_session() is called.
"""
if not self._legacy_facade:
self._legacy_facade = LegacyEngineFacade(None, _factory=self)
if not self._started:
self._start()
return self._legacy_facade
def get_writer_engine(self):
"""Return the writer engine for this factory.
Implies start.
"""
if not self._started:
self._start()
return self._writer_engine
def get_reader_engine(self):
"""Return the reader engine for this factory.
Implies start.
"""
if not self._started:
self._start()
return self._reader_engine
def get_writer_maker(self):
"""Return the writer sessionmaker for this factory.
Implies start.
"""
if not self._started:
self._start()
return self._writer_maker
def get_reader_maker(self):
"""Return the reader sessionmaker for this factory.
Implies start.
"""
if not self._started:
self._start()
return self._reader_maker
def _create_connection(self, mode):
if not self._started:
self._start()
if mode is _WRITER:
return self._writer_engine.connect()
elif self.synchronous_reader or mode is _ASYNC_READER:
return self._reader_engine.connect()
else:
return self._writer_engine.connect()
def _create_session(self, mode, bind=None):
if not self._started:
self._start()
kw = {}
# don't pass 'bind' if bind is None; the sessionmaker
# already has a bind to the engine.
if bind:
kw['bind'] = bind
if mode is _WRITER:
return self._writer_maker(**kw)
elif self.synchronous_reader or mode is _ASYNC_READER:
return self._reader_maker(**kw)
else:
return self._writer_maker(**kw)
def _create_factory_copy(self):
factory = _TransactionFactory()
factory._url_cfg.update(self._url_cfg)
factory._engine_cfg.update(self._engine_cfg)
factory._maker_cfg.update(self._maker_cfg)
factory._transaction_ctx_cfg.update(self._transaction_ctx_cfg)
factory._facade_cfg.update(self._facade_cfg)
return factory
def _args_for_conf(self, default_cfg, conf):
if conf is None:
return dict(
(key, _Default.resolve(value))
for key, value in default_cfg.items()
if _Default.is_set(value)
)
else:
return dict(
(key, _Default.resolve_w_conf(value, conf.database, key))
for key, value in default_cfg.items()
if _Default.is_set_w_conf(value, conf.database, key)
)
def _url_args_for_conf(self, conf):
return self._args_for_conf(self._url_cfg, conf)
def _engine_args_for_conf(self, conf):
return self._args_for_conf(self._engine_cfg, conf)
def _maker_args_for_conf(self, conf):
maker_args = self._args_for_conf(self._maker_cfg, conf)
maker_args['autocommit'] = maker_args.pop('__autocommit')
return maker_args
def dispose_pool(self):
"""Call engine.pool.dispose() on underlying Engine objects."""
with self._start_lock:
if not self._started:
return
self._writer_engine.pool.dispose()
if self._reader_engine is not self._writer_engine:
self._reader_engine.pool.dispose()
def _start(self, conf=False, connection=None, slave_connection=None):
with self._start_lock:
# self._started has been checked on the outside
# when _start() was called. Within the lock,
# check the flag once more to detect the case where
# the start process proceeded while this thread was waiting
# for the lock.
if self._started:
return
if conf is False:
conf = cfg.CONF
# perform register_opts() local to actually using
# the cfg.CONF to maintain exact compatibility with
# the EngineFacade design. This can be changed if needed.
if conf is not None:
conf.register_opts(options.database_opts, 'database')
url_args = self._url_args_for_conf(conf)
if connection:
url_args['connection'] = connection
if slave_connection:
url_args['slave_connection'] = slave_connection
engine_args = self._engine_args_for_conf(conf)
maker_args = self._maker_args_for_conf(conf)
self._writer_engine, self._writer_maker = \
self._setup_for_connection(
url_args['connection'],
engine_args, maker_args)
if url_args.get('slave_connection'):
self._reader_engine, self._reader_maker = \
self._setup_for_connection(
url_args['slave_connection'],
engine_args, maker_args)
else:
self._reader_engine, self._reader_maker = \
self._writer_engine, self._writer_maker
self.synchronous_reader = self._facade_cfg['synchronous_reader']
# set up _started last, so that in case of exceptions
# we try the whole thing again and report errors
# correctly
self._started = True
def _setup_for_connection(
self, sql_connection, engine_kwargs, maker_kwargs):
if sql_connection is None:
raise exception.CantStartEngineError(
"No sql_connection parameter is established")
engine = engines.create_engine(
sql_connection=sql_connection, **engine_kwargs)
for hook in self._facade_cfg['on_engine_create']:
hook(engine)
sessionmaker = orm.get_maker(engine=engine, **maker_kwargs)
return engine, sessionmaker
class _TestTransactionFactory(_TransactionFactory):
"""A :class:`._TransactionFactory` used by test suites.
This is a :class:`._TransactionFactory` that can be directly injected
with an existing engine and sessionmaker.
Note that while this is used by oslo.db's own tests of
the enginefacade system, it is also exported for use by
the test suites of other projects, first as an element of the
oslo_db.sqlalchemy.test_base module, and secondly may be used by
external test suites directly.
Includes a feature to inject itself temporarily as the factory
within the global :class:`._TransactionContextManager`.
"""
@debtcollector.removals.removed_kwarg(
'synchronous_reader',
'argument value is propagated from the parent _TransactionFactory')
def __init__(self, engine, maker, apply_global, from_factory=None, **kw):
# NOTE(zzzeek): **kw needed for backwards compability
self._reader_engine = self._writer_engine = engine
self._reader_maker = self._writer_maker = maker
self._started = True
self._legacy_facade = None
if from_factory is None:
from_factory = _context_manager._factory
self._facade_cfg = from_factory._facade_cfg
self._transaction_ctx_cfg = from_factory._transaction_ctx_cfg
self.synchronous_reader = self._facade_cfg['synchronous_reader']
if apply_global:
self.existing_factory = _context_manager._factory
_context_manager._root_factory = self
def dispose_global(self):
_context_manager._root_factory = self.existing_factory
class _TransactionContext(object):
"""Represent a single database transaction in progress."""
def __init__(self, factory, global_factory=None):
"""Construct a new :class:`.TransactionContext`.
:param factory: the :class:`.TransactionFactory` which will
serve as a source of connectivity.
:param global_factory: the "global" factory which will be used
by the global ``_context_manager`` for new ``_TransactionContext``
objects created under this one. When left as None the actual
"global" factory is used.
"""
self.factory = factory
self.global_factory = global_factory
self.mode = None
self.session = None
self.connection = None
self.transaction = None
kw = self.factory._transaction_ctx_cfg
self.rollback_reader_sessions = kw['rollback_reader_sessions']
self.flush_on_subtransaction = kw['flush_on_subtransaction']
@contextlib.contextmanager
def _connection(self, savepoint=False, context=None):
if self.connection is None:
try:
if self.session is not None:
# use existing session, which is outer to us
self.connection = self.session.connection()
if savepoint:
with self.connection.begin_nested(), \
self._add_context(self.connection, context):
yield self.connection
else:
with self._add_context(self.connection, context):
yield self.connection
else:
# is outermost
self.connection = self.factory._create_connection(
mode=self.mode)
self.transaction = self.connection.begin()
try:
with self._add_context(self.connection, context):
yield self.connection
self._end_connection_transaction(self.transaction)
except Exception:
self.transaction.rollback()
# TODO(zzzeek) do we need save_and_reraise() here,
# or do newer eventlets not have issues? we are using
# raw "raise" in many other places in oslo.db already
# (and one six.reraise()).
raise
finally:
self.transaction = None
self.connection.close()
finally:
self.connection = None
else:
# use existing connection, which is outer to us
if savepoint:
with self.connection.begin_nested(), \
self._add_context(self.connection, context):
yield self.connection
else:
with self._add_context(self.connection, context):
yield self.connection
@contextlib.contextmanager
def _session(self, savepoint=False, context=None):
if self.session is None:
self.session = self.factory._create_session(
bind=self.connection, mode=self.mode)
try:
self.session.begin()
with self._add_context(self.session, context):
yield self.session
self._end_session_transaction(self.session)
except Exception:
with excutils.save_and_reraise_exception():
self.session.rollback()
finally:
self.session.close()
self.session = None
else:
# use existing session, which is outer to us
if savepoint:
with self.session.begin_nested():
with self._add_context(self.session, context):
yield self.session
else:
with self._add_context(self.session, context):
yield self.session
if self.flush_on_subtransaction:
self.session.flush()
@contextlib.contextmanager
def _add_context(self, connection, context):
restore_context = connection.info.get('using_context')
connection.info['using_context'] = context
yield connection
connection.info['using_context'] = restore_context
def _end_session_transaction(self, session):
if self.mode is _WRITER:
session.commit()
elif self.rollback_reader_sessions:
session.rollback()
# In the absence of calling session.rollback(),
# the next call is session.close(). This releases all
# objects from the session into the detached state, and
# releases the connection as well; the connection when returned
# to the pool is either rolled back in any case, or closed fully.
def _end_connection_transaction(self, transaction):
if self.mode is _WRITER:
transaction.commit()
else:
transaction.rollback()
def _produce_block(self, mode, connection, savepoint, allow_async=False,
context=None):
if mode is _WRITER:
self._writer()
elif mode is _ASYNC_READER:
self._async_reader()
else:
self._reader(allow_async)
if connection:
return self._connection(savepoint, context=context)
else:
return self._session(savepoint, context=context)
def _writer(self):
if self.mode is None:
self.mode = _WRITER
elif self.mode is _READER:
raise TypeError(
"Can't upgrade a READER transaction "
"to a WRITER mid-transaction")
elif self.mode is _ASYNC_READER:
raise TypeError(
"Can't upgrade an ASYNC_READER transaction "
"to a WRITER mid-transaction")
def _reader(self, allow_async=False):
if self.mode is None:
self.mode = _READER
elif self.mode is _ASYNC_READER and not allow_async:
raise TypeError(
"Can't upgrade an ASYNC_READER transaction "
"to a READER mid-transaction")
def _async_reader(self):
if self.mode is None:
self.mode = _ASYNC_READER
class _TransactionContextTLocal(threading.local):
def __deepcopy__(self, memo):
return self
def __reduce__(self):
return _TransactionContextTLocal, ()
class _TransactionContextManager(object):
"""Provide context-management and decorator patterns for transactions.
This object integrates user-defined "context" objects with the
:class:`._TransactionContext` class, on behalf of a
contained :class:`._TransactionFactory`.
"""
def __init__(
self, root=None,
mode=None,
independent=False,
savepoint=False,
connection=False,
replace_global_factory=None,
_is_global_manager=False,
allow_async=False):
if root is None:
self._root = self
self._root_factory = _TransactionFactory()
else:
self._root = root
self._replace_global_factory = replace_global_factory
self._is_global_manager = _is_global_manager
self._mode = mode
self._independent = independent
self._savepoint = savepoint
if self._savepoint and self._independent:
raise TypeError(
"setting savepoint and independent makes no sense.")
self._connection = connection
self._allow_async = allow_async
@property
def _factory(self):
"""The :class:`._TransactionFactory` associated with this context."""
return self._root._root_factory
def configure(self, **kw):
"""Apply configurational options to the factory.
This method can only be called before any specific
transaction-beginning methods have been called.
"""
self._factory.configure(**kw)
def append_on_engine_create(self, fn):
"""Append a listener function to _facade_cfg["on_engine_create"]"""
self._factory._facade_cfg['on_engine_create'].append(fn)
def get_legacy_facade(self):
"""Return a :class:`.LegacyEngineFacade` for factory from this context.
This facade will make use of the same engine and sessionmaker
as this factory, however will not share the same transaction context;
the legacy facade continues to work the old way of returning
a new Session each time get_session() is called.
"""
return self._factory.get_legacy_facade()
def get_engine(self):
"""Return the Engine in use.
This will be based on the state being WRITER or READER.
This implies a start operation.
"""
if self._mode is _WRITER:
return self._factory.get_writer_engine()
elif self._mode is _READER:
return self._factory.get_reader_engine()
else:
raise ValueError("mode should be WRITER or READER")
def get_sessionmaker(self):
"""Return the sessionmaker in use.
This will be based on the state being WRITER or READER.
This implies a start operation.
"""
if self._mode is _WRITER:
return self._factory.get_writer_maker()
elif self._mode is _READER:
return self._factory.get_reader_maker()
else:
raise ValueError("mode should be WRITER or READER")
def dispose_pool(self):
"""Call engine.pool.dispose() on underlying Engine objects."""
self._factory.dispose_pool()
def make_new_manager(self):
"""Create a new, independent _TransactionContextManager from this one.
Copies the underlying _TransactionFactory to a new one, so that
it can be further configured with new options.
Used for test environments where the application-wide
_TransactionContextManager may be used as a factory for test-local
managers.
"""
new = self._clone()
new._root = new
new._root_factory = self._root_factory._create_factory_copy()
if new._factory._started:
raise AssertionError('TransactionFactory is already started')
return new
def patch_factory(self, factory_or_manager):
"""Patch a _TransactionFactory into this manager.
Replaces this manager's factory with the given one, and returns
a callable that will reset the factory back to what we
started with.
Only works for root factories. Is intended for test suites
that need to patch in alternate database configurations.
The given argument may be a _TransactionContextManager or a
_TransactionFactory.
"""
if isinstance(factory_or_manager, _TransactionContextManager):
factory = factory_or_manager._factory
elif isinstance(factory_or_manager, _TransactionFactory):
factory = factory_or_manager
else:
raise ValueError(
"_TransactionContextManager or "
"_TransactionFactory expected.")
if self._root is not self:
raise AssertionError('patch_factory only works for root factory.')
existing_factory = self._root_factory
self._root_factory = factory
def reset():
self._root_factory = existing_factory
return reset
def patch_engine(self, engine):
"""Patch an Engine into this manager.
Replaces this manager's factory with a _TestTransactionFactory
that will use the given Engine, and returns
a callable that will reset the factory back to what we
started with.
Only works for root factories. Is intended for test suites
that need to patch in alternate database configurations.
"""
existing_factory = self._factory
if not existing_factory._started:
existing_factory._start()
maker = existing_factory._writer_maker
maker_kwargs = existing_factory._maker_args_for_conf(cfg.CONF)
maker = orm.get_maker(engine=engine, **maker_kwargs)
factory = _TestTransactionFactory(
engine, maker,
apply_global=False,
from_factory=existing_factory
)
return self.patch_factory(factory)
@property
def replace(self):
"""Modifier to replace the global transaction factory with this one."""
return self._clone(replace_global_factory=self._factory)
@property
def writer(self):
"""Modifier to set the transaction to WRITER."""
return self._clone(mode=_WRITER)
@property
def reader(self):
"""Modifier to set the transaction to READER."""
return self._clone(mode=_READER)
@property
def allow_async(self):
"""Modifier to allow async operations
Allows async operations if asynchronous session is already
started in this context. Marking DB API methods with READER would make
it impossible to use them in ASYNC_READER transactions, and marking
them with ASYNC_READER would require a modification of all the places
these DB API methods are called to force READER mode, where the latest
DB state is required.
In Nova DB API methods should have a 'safe' default (i.e. READER),
so that they can start sessions on their own, but it would also be
useful for them to be able to participate in an existing ASYNC_READER
session, if one was started up the stack.
"""
if self._mode is _WRITER:
raise TypeError("Setting async on a WRITER makes no sense")
return self._clone(allow_async=True)
@property
def independent(self):
"""Modifier to start a transaction independent from any enclosing."""
return self._clone(independent=True)
@property
def savepoint(self):
"""Modifier to start a SAVEPOINT if a transaction already exists."""
return self._clone(savepoint=True)
@property
def connection(self):
"""Modifier to return a core Connection object instead of Session."""
return self._clone(connection=True)
@property
def async(self):
"""Modifier to set a READER operation to ASYNC_READER."""
if self._mode is _WRITER:
raise TypeError("Setting async on a WRITER makes no sense")
return self._clone(mode=_ASYNC_READER)
def using(self, context):
"""Provide a context manager block that will use the given context."""
return self._transaction_scope(context)
def __call__(self, fn):
"""Decorate a function."""
argspec = utils.getargspec(fn)
if argspec.args[0] == 'self' or argspec.args[0] == 'cls':
context_index = 1
else:
context_index = 0
@functools.wraps(fn)
def wrapper(*args, **kwargs):
context = args[context_index]
with self._transaction_scope(context):
return fn(*args, **kwargs)
return wrapper
def _clone(self, **kw):
default_kw = {
"independent": self._independent,
"mode": self._mode,
"connection": self._connection
}
default_kw.update(kw)
return _TransactionContextManager(root=self._root, **default_kw)
@contextlib.contextmanager
def _transaction_scope(self, context):
new_transaction = self._independent
transaction_contexts_by_thread = \
_transaction_contexts_by_thread(context)
current = restore = getattr(
transaction_contexts_by_thread, "current", None)
use_factory = self._factory
global_factory = None
if self._replace_global_factory:
use_factory = global_factory = self._replace_global_factory
elif current is not None and current.global_factory:
global_factory = current.global_factory
if self._root._is_global_manager:
use_factory = global_factory
if current is not None and (
new_transaction or current.factory is not use_factory
):
current = None
if current is None:
current = transaction_contexts_by_thread.current = \
_TransactionContext(use_factory, global_factory=global_factory)
try:
if self._mode is not None:
with current._produce_block(
mode=self._mode,
connection=self._connection,
savepoint=self._savepoint,
allow_async=self._allow_async,
context=context) as resource:
yield resource
else:
yield
finally:
if restore is None:
del transaction_contexts_by_thread.current
elif current is not restore:
transaction_contexts_by_thread.current = restore
def _context_descriptor(attr=None):
getter = operator.attrgetter(attr)
def _property_for_context(context):
try:
transaction_context = context.transaction_ctx
except exception.NoEngineContextEstablished:
raise exception.NoEngineContextEstablished(
"No TransactionContext is established for "
"this %s object within the current thread; "
"the %r attribute is unavailable."
% (context, attr)
)
else:
result = getter(transaction_context)
if result is None:
raise exception.ContextNotRequestedError(
"The '%s' context attribute was requested but "
"it has not been established for this context." % attr
)
return result
return property(_property_for_context)
def _transaction_ctx_for_context(context):
by_thread = _transaction_contexts_by_thread(context)
try:
return by_thread.current
except AttributeError:
raise exception.NoEngineContextEstablished(
"No TransactionContext is established for "
"this %s object within the current thread. "
% context
)
def _transaction_contexts_by_thread(context):
transaction_contexts_by_thread = getattr(
context, '_enginefacade_context', None)
if transaction_contexts_by_thread is None:
transaction_contexts_by_thread = \
context._enginefacade_context = _TransactionContextTLocal()
return transaction_contexts_by_thread
def transaction_context_provider(klass):
"""Decorate a class with ``session`` and ``connection`` attributes."""
setattr(
klass,
'transaction_ctx',
property(_transaction_ctx_for_context))
# Graft transaction context attributes as context properties
for attr in ('session', 'connection', 'transaction'):
setattr(klass, attr, _context_descriptor(attr))
return klass
_context_manager = _TransactionContextManager(_is_global_manager=True)
"""default context manager."""
def transaction_context():
"""Construct a local transaction context.
"""
return _TransactionContextManager()
def configure(**kw):
"""Apply configurational options to the global factory.
This method can only be called before any specific transaction-beginning
methods have been called.
.. seealso::
:meth:`._TransactionFactory.configure`
"""
_context_manager._factory.configure(**kw)
def get_legacy_facade():
"""Return a :class:`.LegacyEngineFacade` for the global factory.
This facade will make use of the same engine and sessionmaker
as this factory, however will not share the same transaction context;
the legacy facade continues to work the old way of returning
a new Session each time get_session() is called.
"""
return _context_manager.get_legacy_facade()
reader = _context_manager.reader
"""The global 'reader' starting point."""
writer = _context_manager.writer
"""The global 'writer' starting point."""
class LegacyEngineFacade(object):
"""A helper class for removing of global engine instances from oslo.db.
.. deprecated:: 1.12.0
Please use :mod:`oslo_db.sqlalchemy.enginefacade` for new development.
As a library, oslo.db can't decide where to store/when to create engine
and sessionmaker instances, so this must be left for a target application.
On the other hand, in order to simplify the adoption of oslo.db changes,
we'll provide a helper class, which creates engine and sessionmaker
on its instantiation and provides get_engine()/get_session() methods
that are compatible with corresponding utility functions that currently
exist in target projects, e.g. in Nova.
engine/sessionmaker instances will still be global (and they are meant to
be global), but they will be stored in the app context, rather that in the
oslo.db context.
Two important things to remember:
1. An Engine instance is effectively a pool of DB connections, so it's
meant to be shared (and it's thread-safe).
2. A Session instance is not meant to be shared and represents a DB
transactional context (i.e. it's not thread-safe). sessionmaker is
a factory of sessions.
:param sql_connection: the connection string for the database to use
:type sql_connection: string
:param slave_connection: the connection string for the 'slave' database
to use. If not provided, the master database
will be used for all operations. Note: this
is meant to be used for offloading of read
operations to asynchronously replicated slaves
to reduce the load on the master database.
:type slave_connection: string
:param sqlite_fk: enable foreign keys in SQLite
:type sqlite_fk: bool
:param autocommit: use autocommit mode for created Session instances
:type autocommit: bool
:param expire_on_commit: expire session objects on commit
:type expire_on_commit: bool
Keyword arguments:
:keyword mysql_sql_mode: the SQL mode to be used for MySQL sessions.
(defaults to TRADITIONAL)
:keyword mysql_enable_ndb: If True, transparently enables support for
handling MySQL Cluster (NDB).
(defaults to False)
:keyword connection_recycle_time: Time period for connections to be
recycled upon checkout (defaults to 3600)
:keyword connection_debug: verbosity of SQL debugging information.
-1=Off, 0=None, 100=Everything (defaults
to 0)
:keyword max_pool_size: maximum number of SQL connections to keep open
in a pool (defaults to SQLAlchemy settings)
:keyword max_overflow: if set, use this value for max_overflow with
sqlalchemy (defaults to SQLAlchemy settings)
:keyword pool_timeout: if set, use this value for pool_timeout with
sqlalchemy (defaults to SQLAlchemy settings)
:keyword sqlite_synchronous: if True, SQLite uses synchronous mode
(defaults to True)
:keyword connection_trace: add python stack traces to SQL as comment
strings (defaults to False)
:keyword max_retries: maximum db connection retries during startup.
(setting -1 implies an infinite retry count)
(defaults to 10)
:keyword retry_interval: interval between retries of opening a sql
connection (defaults to 10)
:keyword thread_checkin: boolean that indicates that between each
engine checkin event a sleep(0) will occur to
allow other greenthreads to run (defaults to
True)
"""
def __init__(self, sql_connection, slave_connection=None,
sqlite_fk=False, autocommit=True,
expire_on_commit=False, _conf=None, _factory=None, **kwargs):
warnings.warn(
"EngineFacade is deprecated; please use "
"oslo_db.sqlalchemy.enginefacade",
exception.OsloDBDeprecationWarning,
stacklevel=2)
if _factory:
self._factory = _factory
else:
self._factory = _TransactionFactory()
self._factory.configure(
sqlite_fk=sqlite_fk,
__autocommit=autocommit,
expire_on_commit=expire_on_commit,
**kwargs
)
# make sure passed-in urls are favored over that
# of config
self._factory._start(
_conf, connection=sql_connection,
slave_connection=slave_connection)
def _check_factory_started(self):
if not self._factory._started:
self._factory._start()
def get_engine(self, use_slave=False):
"""Get the engine instance (note, that it's shared).
:param use_slave: if possible, use 'slave' database for this engine.
If the connection string for the slave database
wasn't provided, 'master' engine will be returned.
(defaults to False)
:type use_slave: bool
"""
self._check_factory_started()
if use_slave:
return self._factory._reader_engine
else:
return self._factory._writer_engine
def get_session(self, use_slave=False, **kwargs):
"""Get a Session instance.
:param use_slave: if possible, use 'slave' database connection for
this session. If the connection string for the
slave database wasn't provided, a session bound
to the 'master' engine will be returned.
(defaults to False)
:type use_slave: bool
Keyword arguments will be passed to a sessionmaker instance as is (if
passed, they will override the ones used when the sessionmaker instance
was created). See SQLAlchemy Session docs for details.
"""
self._check_factory_started()
if use_slave:
return self._factory._reader_maker(**kwargs)
else:
return self._factory._writer_maker(**kwargs)
def get_sessionmaker(self, use_slave=False):
"""Get the sessionmaker instance used to create a Session.
This can be called for those cases where the sessionmaker() is to
be temporarily injected with some state such as a specific connection.
"""
self._check_factory_started()
if use_slave:
return self._factory._reader_maker
else:
return self._factory._writer_maker
@classmethod
def from_config(cls, conf,
sqlite_fk=False, autocommit=True, expire_on_commit=False):
"""Initialize EngineFacade using oslo.config config instance options.
:param conf: oslo.config config instance
:type conf: oslo_config.cfg.ConfigOpts
:param sqlite_fk: enable foreign keys in SQLite
:type sqlite_fk: bool
:param autocommit: use autocommit mode for created Session instances
:type autocommit: bool
:param expire_on_commit: expire session objects on commit
:type expire_on_commit: bool
"""
return cls(
None,
sqlite_fk=sqlite_fk,
autocommit=autocommit,
expire_on_commit=expire_on_commit, _conf=conf)
|