1 # Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at:
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
20 from ovs.db import error
25 vlog = ovs.vlog.Vlog("idl")
27 __pychecker__ = 'no-classattr no-objattrs'
35 """Open vSwitch Database Interface Definition Language (OVSDB IDL).
37 The OVSDB IDL maintains an in-memory replica of a database. It issues RPC
38 requests to an OVSDB database server and parses the responses, converting
39 raw JSON into data structures that are easier for clients to digest.
41 The IDL also assists with issuing database transactions. The client
42 creates a transaction, manipulates the IDL data structures, and commits or
43 aborts the transaction. The IDL then composes and issues the necessary
44 JSON-RPC requests and reports to the client whether the transaction
45 completed successfully.
47 The client is allowed to access the following attributes directly, in a
50 - 'tables': This is the 'tables' map in the ovs.db.schema.DbSchema provided
51 to the Idl constructor. Each ovs.db.schema.TableSchema in the map is
52 annotated with a new attribute 'rows', which is a dict from a uuid.UUID
55 The client may directly read and write the Row objects referenced by the
56 'rows' map values. Refer to Row for more details.
58 - 'change_seqno': A number that represents the IDL's state. When the IDL
59 is updated (by Idl.run()), its value changes. The sequence number can
60 occasionally change even if the database does not. This happens if the
61 connection to the database drops and reconnects, which causes the
62 database contents to be reloaded even if they didn't change. (It could
63 also happen if the database server sends out a "change" that reflects
64 what the IDL already thought was in the database. The database server is
65 not supposed to do that, but bugs could in theory cause it to do so.)
67 - 'lock_name': The name of the lock configured with Idl.set_lock(), or None
68 if no lock is configured.
70 - 'has_lock': True, if the IDL is configured to obtain a lock and owns that
71 lock, and False otherwise.
73 Locking and unlocking happens asynchronously from the database client's
74 point of view, so the information is only useful for optimization
75 (e.g. if the client doesn't have the lock then there's no point in trying
76 to write to the database).
78 - 'is_lock_contended': True, if the IDL is configured to obtain a lock but
79 the database server has indicated that some other client already owns the
80 requested lock, and False otherwise.
82 - 'txn': The ovs.db.idl.Transaction object for the database transaction
83 currently being constructed, if there is one, or None otherwise.
86 def __init__(self, remote, schema):
87 """Creates and returns a connection to the database named 'db_name' on
88 'remote', which should be in a form acceptable to
89 ovs.jsonrpc.session.open(). The connection will maintain an in-memory
90 replica of the remote database.
92 'schema' should be the schema for the remote database. The caller may
93 have cut it down by removing tables or columns that are not of
94 interest. The IDL will only replicate the tables and columns that
95 remain. The caller may also add a attribute named 'alert' to selected
96 remaining columns, setting its value to False; if so, then changes to
97 those columns will not be considered changes to the database for the
98 purpose of the return value of Idl.run() and Idl.change_seqno. This is
99 useful for columns that the IDL's client will write but not read.
101 As a convenience to users, 'schema' may also be an instance of the
104 The IDL uses and modifies 'schema' directly."""
106 assert isinstance(schema, SchemaHelper)
107 schema = schema.get_idl_schema()
109 self.tables = schema.tables
110 self.readonly = schema.readonly
112 self._session = ovs.jsonrpc.Session.open(remote)
113 self._monitor_request_id = None
114 self._last_seqno = None
115 self.change_seqno = 0
118 self.lock_name = None # Name of lock we need, None if none.
119 self.has_lock = False # Has db server said we have the lock?
120 self.is_lock_contended = False # Has db server said we can't get lock?
121 self._lock_request_id = None # JSON-RPC ID of in-flight lock request.
123 # Transaction support.
125 self._outstanding_txns = {}
127 for table in schema.tables.itervalues():
128 for column in table.columns.itervalues():
129 if not hasattr(column, 'alert'):
131 table.need_table = False
136 """Closes the connection to the database. The IDL will no longer
138 self._session.close()
141 """Processes a batch of messages from the database server. Returns
142 True if the database as seen through the IDL changed, False if it did
143 not change. The initial fetch of the entire contents of the remote
144 database is considered to be one kind of change. If the IDL has been
145 configured to acquire a database lock (with Idl.set_lock()), then
146 successfully acquiring the lock is also considered to be a change.
148 This function can return occasional false positives, that is, report
149 that the database changed even though it didn't. This happens if the
150 connection to the database drops and reconnects, which causes the
151 database contents to be reloaded even if they didn't change. (It could
152 also happen if the database server sends out a "change" that reflects
153 what we already thought was in the database, but the database server is
154 not supposed to do that.)
156 As an alternative to checking the return value, the client may check
157 for changes in self.change_seqno."""
159 initial_change_seqno = self.change_seqno
164 if not self._session.is_connected():
167 seqno = self._session.get_seqno()
168 if seqno != self._last_seqno:
169 self._last_seqno = seqno
170 self.__txn_abort_all()
171 self.__send_monitor_request()
173 self.__send_lock_request()
176 msg = self._session.recv()
179 if (msg.type == ovs.jsonrpc.Message.T_NOTIFY
180 and msg.method == "update"
181 and len(msg.params) == 2
182 and msg.params[0] is None):
183 # Database contents changed.
184 self.__parse_update(msg.params[1])
185 elif (msg.type == ovs.jsonrpc.Message.T_REPLY
186 and self._monitor_request_id is not None
187 and self._monitor_request_id == msg.id):
188 # Reply to our "monitor" request.
190 self.change_seqno += 1
191 self._monitor_request_id = None
193 self.__parse_update(msg.result)
194 except error.Error as e:
195 vlog.err("%s: parse error in received schema: %s"
196 % (self._session.get_name(), e))
198 elif (msg.type == ovs.jsonrpc.Message.T_REPLY
199 and self._lock_request_id is not None
200 and self._lock_request_id == msg.id):
201 # Reply to our "lock" request.
202 self.__parse_lock_reply(msg.result)
203 elif (msg.type == ovs.jsonrpc.Message.T_NOTIFY
204 and msg.method == "locked"):
206 self.__parse_lock_notify(msg.params, True)
207 elif (msg.type == ovs.jsonrpc.Message.T_NOTIFY
208 and msg.method == "stolen"):
209 # Someone else stole our lock.
210 self.__parse_lock_notify(msg.params, False)
211 elif msg.type == ovs.jsonrpc.Message.T_NOTIFY and msg.id == "echo":
212 # Reply to our echo request. Ignore it.
214 elif (msg.type in (ovs.jsonrpc.Message.T_ERROR,
215 ovs.jsonrpc.Message.T_REPLY)
216 and self.__txn_process_reply(msg)):
217 # __txn_process_reply() did everything needed.
220 # This can happen if a transaction is destroyed before we
221 # receive the reply, so keep the log level low.
222 vlog.dbg("%s: received unexpected %s message"
223 % (self._session.get_name(),
224 ovs.jsonrpc.Message.type_to_string(msg.type)))
226 return initial_change_seqno != self.change_seqno
228 def wait(self, poller):
229 """Arranges for poller.block() to wake up when self.run() has something
230 to do or when activity occurs on a transaction on 'self'."""
231 self._session.wait(poller)
232 self._session.recv_wait(poller)
234 def has_ever_connected(self):
235 """Returns True, if the IDL successfully connected to the remote
236 database and retrieved its contents (even if the connection
237 subsequently dropped and is in the process of reconnecting). If so,
238 then the IDL contains an atomic snapshot of the database's contents
239 (but it might be arbitrarily old if the connection dropped).
241 Returns False if the IDL has never connected or retrieved the
242 database's contents. If so, the IDL is empty."""
243 return self.change_seqno != 0
245 def force_reconnect(self):
246 """Forces the IDL to drop its connection to the database and reconnect.
247 In the meantime, the contents of the IDL will not change."""
248 self._session.force_reconnect()
250 def set_lock(self, lock_name):
251 """If 'lock_name' is not None, configures the IDL to obtain the named
252 lock from the database server and to avoid modifying the database when
253 the lock cannot be acquired (that is, when another client has the same
256 If 'lock_name' is None, drops the locking requirement and releases the
259 assert not self._outstanding_txns
261 if self.lock_name and (not lock_name or lock_name != self.lock_name):
262 # Release previous lock.
263 self.__send_unlock_request()
264 self.lock_name = None
265 self.is_lock_contended = False
267 if lock_name and not self.lock_name:
269 self.lock_name = lock_name
270 self.__send_lock_request()
272 def notify(self, event, row, updates=None):
273 """Hook for implementing create/update/delete notifications
275 :param event: The event that was triggered
276 :type event: ROW_CREATE, ROW_UPDATE, or ROW_DELETE
277 :param row: The row as it is after the operation has occured
279 :param updates: For updates, a Row object with just the changed columns
286 for table in self.tables.itervalues():
292 self.change_seqno += 1
294 def __update_has_lock(self, new_has_lock):
295 if new_has_lock and not self.has_lock:
296 if self._monitor_request_id is None:
297 self.change_seqno += 1
299 # We're waiting for a monitor reply, so don't signal that the
300 # database changed. The monitor reply will increment
301 # change_seqno anyhow.
303 self.is_lock_contended = False
304 self.has_lock = new_has_lock
306 def __do_send_lock_request(self, method):
307 self.__update_has_lock(False)
308 self._lock_request_id = None
309 if self._session.is_connected():
310 msg = ovs.jsonrpc.Message.create_request(method, [self.lock_name])
312 self._session.send(msg)
317 def __send_lock_request(self):
318 self._lock_request_id = self.__do_send_lock_request("lock")
320 def __send_unlock_request(self):
321 self.__do_send_lock_request("unlock")
323 def __parse_lock_reply(self, result):
324 self._lock_request_id = None
325 got_lock = type(result) == dict and result.get("locked") is True
326 self.__update_has_lock(got_lock)
328 self.is_lock_contended = True
330 def __parse_lock_notify(self, params, new_has_lock):
331 if (self.lock_name is not None
332 and type(params) in (list, tuple)
334 and params[0] == self.lock_name):
335 self.__update_has_lock(new_has_lock)
337 self.is_lock_contended = True
339 def __send_monitor_request(self):
340 monitor_requests = {}
341 for table in self.tables.itervalues():
343 for column in table.columns.keys():
344 if ((table.name not in self.readonly) or
345 (table.name in self.readonly) and
346 (column not in self.readonly[table.name])):
347 columns.append(column)
348 monitor_requests[table.name] = {"columns": columns}
349 msg = ovs.jsonrpc.Message.create_request(
350 "monitor", [self._db.name, None, monitor_requests])
351 self._monitor_request_id = msg.id
352 self._session.send(msg)
354 def __parse_update(self, update):
356 self.__do_parse_update(update)
357 except error.Error as e:
358 vlog.err("%s: error parsing update: %s"
359 % (self._session.get_name(), e))
361 def __do_parse_update(self, table_updates):
362 if type(table_updates) != dict:
363 raise error.Error("<table-updates> is not an object",
366 for table_name, table_update in table_updates.iteritems():
367 table = self.tables.get(table_name)
369 raise error.Error('<table-updates> includes unknown '
370 'table "%s"' % table_name)
372 if type(table_update) != dict:
373 raise error.Error('<table-update> for table "%s" is not '
374 'an object' % table_name, table_update)
376 for uuid_string, row_update in table_update.iteritems():
377 if not ovs.ovsuuid.is_valid_string(uuid_string):
378 raise error.Error('<table-update> for table "%s" '
379 'contains bad UUID "%s" as member '
380 'name' % (table_name, uuid_string),
382 uuid = ovs.ovsuuid.from_string(uuid_string)
384 if type(row_update) != dict:
385 raise error.Error('<table-update> for table "%s" '
386 'contains <row-update> for %s that '
388 % (table_name, uuid_string))
390 parser = ovs.db.parser.Parser(row_update, "row-update")
391 old = parser.get_optional("old", [dict])
392 new = parser.get_optional("new", [dict])
395 if not old and not new:
396 raise error.Error('<row-update> missing "old" and '
397 '"new" members', row_update)
399 if self.__process_update(table, uuid, old, new):
400 self.change_seqno += 1
402 def __process_update(self, table, uuid, old, new):
403 """Returns True if a column changed, False otherwise."""
404 row = table.rows.get(uuid)
411 self.notify(ROW_DELETE, row)
414 vlog.warn("cannot delete missing row %s from table %s"
415 % (uuid, table.name))
419 row = self.__create_row(table, uuid)
423 vlog.warn("cannot add existing row %s to table %s"
424 % (uuid, table.name))
425 if self.__row_update(table, row, new):
427 self.notify(ROW_CREATE, row)
431 row = self.__create_row(table, uuid)
435 vlog.warn("cannot modify missing row %s in table %s"
436 % (uuid, table.name))
437 if self.__row_update(table, row, new):
439 self.notify(op, row, Row.from_json(self, table, uuid, old))
442 def __row_update(self, table, row, row_json):
444 for column_name, datum_json in row_json.iteritems():
445 column = table.columns.get(column_name)
448 vlog.warn("unknown column %s updating table %s"
449 % (column_name, table.name))
453 datum = ovs.db.data.Datum.from_json(column.type, datum_json)
454 except error.Error as e:
456 vlog.warn("error parsing column %s in table %s: %s"
457 % (column_name, table.name, e))
460 if datum != row._data[column_name]:
461 row._data[column_name] = datum
465 # Didn't really change but the OVSDB monitor protocol always
466 # includes every value in a row.
470 def __create_row(self, table, uuid):
472 for column in table.columns.itervalues():
473 data[column.name] = ovs.db.data.Datum.default(column.type)
474 row = table.rows[uuid] = Row(self, table, uuid, data)
478 self._session.force_reconnect()
480 def __txn_abort_all(self):
481 while self._outstanding_txns:
482 txn = self._outstanding_txns.popitem()[1]
483 txn._status = Transaction.TRY_AGAIN
485 def __txn_process_reply(self, msg):
486 txn = self._outstanding_txns.pop(msg.id, None)
488 txn._process_reply(msg)
491 def _uuid_to_row(atom, base):
493 return base.ref_table.rows.get(atom)
498 def _row_to_uuid(value):
499 if type(value) == Row:
506 """A row within an IDL.
508 The client may access the following attributes directly:
510 - 'uuid': a uuid.UUID object whose value is the row's database UUID.
512 - An attribute for each column in the Row's table, named for the column,
513 whose values are as returned by Datum.to_python() for the column's type.
515 If some error occurs (e.g. the database server's idea of the column is
516 different from the IDL's idea), then the attribute values is the
517 "default" value return by Datum.default() for the column's type. (It is
518 important to know this because the default value may violate constraints
519 for the column's type, e.g. the default integer value is 0 even if column
520 contraints require the column's value to be positive.)
522 When a transaction is active, column attributes may also be assigned new
523 values. Committing the transaction will then cause the new value to be
524 stored into the database.
526 *NOTE*: In the current implementation, the value of a column is a *copy*
527 of the value in the database. This means that modifying its value
528 directly will have no useful effect. For example, the following:
529 row.mycolumn["a"] = "b" # don't do this
530 will not change anything in the database, even after commit. To modify
531 the column, instead assign the modified column value back to the column:
536 def __init__(self, idl, table, uuid, data):
537 # All of the explicit references to self.__dict__ below are required
538 # to set real attributes with invoking self.__getattr__().
539 self.__dict__["uuid"] = uuid
541 self.__dict__["_idl"] = idl
542 self.__dict__["_table"] = table
544 # _data is the committed data. It takes the following values:
546 # - A dictionary that maps every column name to a Datum, if the row
547 # exists in the committed form of the database.
549 # - None, if this row is newly inserted within the active transaction
550 # and thus has no committed form.
551 self.__dict__["_data"] = data
553 # _changes describes changes to this row within the active transaction.
554 # It takes the following values:
556 # - {}, the empty dictionary, if no transaction is active or if the
557 # row has yet not been changed within this transaction.
559 # - A dictionary that maps a column name to its new Datum, if an
560 # active transaction changes those columns' values.
562 # - A dictionary that maps every column name to a Datum, if the row
563 # is newly inserted within the active transaction.
565 # - None, if this transaction deletes this row.
566 self.__dict__["_changes"] = {}
568 # A dictionary whose keys are the names of columns that must be
569 # verified as prerequisites when the transaction commits. The values
570 # in the dictionary are all None.
571 self.__dict__["_prereqs"] = {}
573 def __getattr__(self, column_name):
574 assert self._changes is not None
576 datum = self._changes.get(column_name)
578 if self._data is None:
579 raise AttributeError("%s instance has no attribute '%s'" %
580 (self.__class__.__name__, column_name))
581 if column_name in self._data:
582 datum = self._data[column_name]
584 raise AttributeError("%s instance has no attribute '%s'" %
585 (self.__class__.__name__, column_name))
587 return datum.to_python(_uuid_to_row)
589 def __setattr__(self, column_name, value):
590 assert self._changes is not None
593 if ((self._table.name in self._idl.readonly) and
594 (column_name in self._idl.readonly[self._table.name])):
595 vlog.warn("attempting to write to readonly column %s"
599 column = self._table.columns[column_name]
601 datum = ovs.db.data.Datum.from_python(column.type, value,
603 except error.Error as e:
605 vlog.err("attempting to write bad value to column %s (%s)"
608 self._idl.txn._write(self, column, datum)
611 def from_json(cls, idl, table, uuid, row_json):
613 for column_name, datum_json in row_json.iteritems():
614 column = table.columns.get(column_name)
617 vlog.warn("unknown column %s in table %s"
618 % (column_name, table.name))
621 datum = ovs.db.data.Datum.from_json(column.type, datum_json)
622 except error.Error as e:
624 vlog.warn("error parsing column %s in table %s: %s"
625 % (column_name, table.name, e))
627 data[column_name] = datum
628 return cls(idl, table, uuid, data)
630 def verify(self, column_name):
631 """Causes the original contents of column 'column_name' in this row to
632 be verified as a prerequisite to completing the transaction. That is,
633 if 'column_name' changed in this row (or if this row was deleted)
634 between the time that the IDL originally read its contents and the time
635 that the transaction commits, then the transaction aborts and
636 Transaction.commit() returns Transaction.TRY_AGAIN.
638 The intention is that, to ensure that no transaction commits based on
639 dirty reads, an application should call Row.verify() on each data item
640 read as part of a read-modify-write operation.
642 In some cases Row.verify() reduces to a no-op, because the current
643 value of the column is already known:
645 - If this row is a row created by the current transaction (returned
646 by Transaction.insert()).
648 - If the column has already been modified within the current
651 Because of the latter property, always call Row.verify() *before*
652 modifying the column, for a given read-modify-write.
654 A transaction must be in progress."""
656 assert self._changes is not None
657 if not self._data or column_name in self._changes:
660 self._prereqs[column_name] = None
663 """Deletes this row from its table.
665 A transaction must be in progress."""
667 assert self._changes is not None
668 if self._data is None:
669 del self._idl.txn._txn_rows[self.uuid]
671 self._idl.txn._txn_rows[self.uuid] = self
672 self.__dict__["_changes"] = None
673 del self._table.rows[self.uuid]
675 def fetch(self, column_name):
676 self._idl.txn._fetch(self, column_name)
678 def increment(self, column_name):
679 """Causes the transaction, when committed, to increment the value of
680 'column_name' within this row by 1. 'column_name' must have an integer
681 type. After the transaction commits successfully, the client may
682 retrieve the final (incremented) value of 'column_name' with
683 Transaction.get_increment_new_value().
685 The client could accomplish something similar by reading and writing
686 and verify()ing columns. However, increment() will never (by itself)
687 cause a transaction to fail because of a verify error.
689 The intended use is for incrementing the "next_cfg" column in
690 the Open_vSwitch table."""
691 self._idl.txn._increment(self, column_name)
694 def _uuid_name_from_uuid(uuid):
695 return "row%s" % str(uuid).replace("-", "_")
698 def _where_uuid_equals(uuid):
699 return [["_uuid", "==", ["uuid", str(uuid)]]]
702 class _InsertedRow(object):
703 def __init__(self, op_index):
704 self.op_index = op_index
708 class Transaction(object):
709 """A transaction may modify the contents of a database by modifying the
710 values of columns, deleting rows, inserting rows, or adding checks that
711 columns in the database have not changed ("verify" operations), through
714 Reading and writing columns and inserting and deleting rows are all
715 straightforward. The reasons to verify columns are less obvious.
716 Verification is the key to maintaining transactional integrity. Because
717 OVSDB handles multiple clients, it can happen that between the time that
718 OVSDB client A reads a column and writes a new value, OVSDB client B has
719 written that column. Client A's write should not ordinarily overwrite
720 client B's, especially if the column in question is a "map" column that
721 contains several more or less independent data items. If client A adds a
722 "verify" operation before it writes the column, then the transaction fails
723 in case client B modifies it first. Client A will then see the new value
724 of the column and compose a new transaction based on the new contents
727 When a transaction is complete, which must be before the next call to
728 Idl.run(), call Transaction.commit() or Transaction.abort().
730 The life-cycle of a transaction looks like this:
732 1. Create the transaction and record the initial sequence number:
734 seqno = idl.change_seqno(idl)
735 txn = Transaction(idl)
737 2. Modify the database with Row and Transaction methods.
739 3. Commit the transaction by calling Transaction.commit(). The first call
740 to this function probably returns Transaction.INCOMPLETE. The client
741 must keep calling again along as this remains true, calling Idl.run() in
742 between to let the IDL do protocol processing. (If the client doesn't
743 have anything else to do in the meantime, it can use
744 Transaction.commit_block() to avoid having to loop itself.)
746 4. If the final status is Transaction.TRY_AGAIN, wait for Idl.change_seqno
747 to change from the saved 'seqno' (it's possible that it's already
748 changed, in which case the client should not wait at all), then start
749 over from step 1. Only a call to Idl.run() will change the return value
750 of Idl.change_seqno. (Transaction.commit_block() calls Idl.run().)"""
752 # Status values that Transaction.commit() can return.
754 # Not yet committed or aborted.
755 UNCOMMITTED = "uncommitted"
756 # Transaction didn't include any changes.
757 UNCHANGED = "unchanged"
758 # Commit in progress, please wait.
759 INCOMPLETE = "incomplete"
760 # ovsdb_idl_txn_abort() called.
764 # Commit failed because a "verify" operation
765 # reported an inconsistency, due to a network
766 # problem, or other transient failure. Wait
767 # for a change, then try again.
768 TRY_AGAIN = "try again"
769 # Server hasn't given us the lock yet.
770 NOT_LOCKED = "not locked"
771 # Commit failed due to a hard error.
775 def status_to_string(status):
776 """Converts one of the status values that Transaction.commit() can
777 return into a human-readable string.
779 (The status values are in fact such strings already, so
780 there's nothing to do.)"""
783 def __init__(self, idl):
784 """Starts a new transaction on 'idl' (an instance of ovs.db.idl.Idl).
785 A given Idl may only have a single active transaction at a time.
787 A Transaction may modify the contents of a database by assigning new
788 values to columns (attributes of Row), deleting rows (with
789 Row.delete()), or inserting rows (with Transaction.insert()). It may
790 also check that columns in the database have not changed with
793 When a transaction is complete (which must be before the next call to
794 Idl.run()), call Transaction.commit() or Transaction.abort()."""
795 assert idl.txn is None
798 self._request_id = None
802 self._status = Transaction.UNCOMMITTED
807 self._inc_column = None
809 self._fetch_requests = []
811 self._inserted_rows = {} # Map from UUID to _InsertedRow
813 def add_comment(self, comment):
814 """Appends 'comment' to the comments that will be passed to the OVSDB
815 server when this transaction is committed. (The comment will be
816 committed to the OVSDB log, which "ovsdb-tool show-log" can print in a
817 relatively human-readable form.)"""
818 self._comments.append(comment)
820 def wait(self, poller):
821 """Causes poll_block() to wake up if this transaction has completed
823 if self._status not in (Transaction.UNCOMMITTED,
824 Transaction.INCOMPLETE):
825 poller.immediate_wake()
827 def _substitute_uuids(self, json):
828 if type(json) in (list, tuple):
830 and json[0] == 'uuid'
831 and ovs.ovsuuid.is_valid_string(json[1])):
832 uuid = ovs.ovsuuid.from_string(json[1])
833 row = self._txn_rows.get(uuid, None)
834 if row and row._data is None:
835 return ["named-uuid", _uuid_name_from_uuid(uuid)]
837 return [self._substitute_uuids(elem) for elem in json]
840 def __disassemble(self):
843 for row in self._txn_rows.itervalues():
844 if row._changes is None:
845 row._table.rows[row.uuid] = row
846 elif row._data is None:
847 del row._table.rows[row.uuid]
848 row.__dict__["_changes"] = {}
849 row.__dict__["_prereqs"] = {}
853 """Attempts to commit 'txn'. Returns the status of the commit
854 operation, one of the following constants:
856 Transaction.INCOMPLETE:
858 The transaction is in progress, but not yet complete. The caller
859 should call again later, after calling Idl.run() to let the
860 IDL do OVSDB protocol processing.
862 Transaction.UNCHANGED:
864 The transaction is complete. (It didn't actually change the
865 database, so the IDL didn't send any request to the database
870 The caller previously called Transaction.abort().
874 The transaction was successful. The update made by the
875 transaction (and possibly other changes made by other database
876 clients) should already be visible in the IDL.
878 Transaction.TRY_AGAIN:
880 The transaction failed for some transient reason, e.g. because a
881 "verify" operation reported an inconsistency or due to a network
882 problem. The caller should wait for a change to the database,
883 then compose a new transaction, and commit the new transaction.
885 Use Idl.change_seqno to wait for a change in the database. It is
886 important to use its value *before* the initial call to
887 Transaction.commit() as the baseline for this purpose, because
888 the change that one should wait for can happen after the initial
889 call but before the call that returns Transaction.TRY_AGAIN, and
890 using some other baseline value in that situation could cause an
891 indefinite wait if the database rarely changes.
893 Transaction.NOT_LOCKED:
895 The transaction failed because the IDL has been configured to
896 require a database lock (with Idl.set_lock()) but didn't
897 get it yet or has already lost it.
899 Committing a transaction rolls back all of the changes that it made to
900 the IDL's copy of the database. If the transaction commits
901 successfully, then the database server will send an update and, thus,
902 the IDL will be updated with the committed changes."""
903 # The status can only change if we're the active transaction.
904 # (Otherwise, our status will change only in Idl.run().)
905 if self != self.idl.txn:
908 # If we need a lock but don't have it, give up quickly.
909 if self.idl.lock_name and not self.idl.has_lock:
910 self._status = Transaction.NOT_LOCKED
914 operations = [self.idl._db.name]
916 # Assert that we have the required lock (avoiding a race).
917 if self.idl.lock_name:
918 operations.append({"op": "assert",
919 "lock": self.idl.lock_name})
921 # Add prerequisites and declarations of new rows.
922 for row in self._txn_rows.itervalues():
926 for column_name in row._prereqs:
927 columns.append(column_name)
928 rows[column_name] = row._data[column_name].to_json()
929 operations.append({"op": "wait",
930 "table": row._table.name,
932 "where": _where_uuid_equals(row.uuid),
939 for row in self._txn_rows.itervalues():
940 if row._changes is None:
941 if row._table.is_root:
942 operations.append({"op": "delete",
943 "table": row._table.name,
944 "where": _where_uuid_equals(row.uuid)})
947 # Let ovsdb-server decide whether to really delete it.
950 op = {"table": row._table.name}
951 if row._data is None:
953 op["uuid-name"] = _uuid_name_from_uuid(row.uuid)
956 op_index = len(operations) - 1
957 self._inserted_rows[row.uuid] = _InsertedRow(op_index)
960 op["where"] = _where_uuid_equals(row.uuid)
965 for column_name, datum in row._changes.iteritems():
966 if row._data is not None or not datum.is_default():
967 row_json[column_name] = (
968 self._substitute_uuids(datum.to_json()))
970 # If anything really changed, consider it an update.
971 # We can't suppress not-really-changed values earlier
972 # or transactions would become nonatomic (see the big
973 # comment inside Transaction._write()).
974 if (not any_updates and row._data is not None and
975 row._data[column_name] != datum):
978 if row._data is None or row_json:
979 operations.append(op)
981 if self._fetch_requests:
982 for fetch in self._fetch_requests:
983 fetch["index"] = len(operations) - 1
984 operations.append({"op": "select",
985 "table": fetch["row"]._table.name,
986 "where": self._substitute_uuids(
987 _where_uuid_equals(fetch["row"].uuid)),
988 "columns": [fetch["column_name"]]})
992 if self._inc_row and any_updates:
993 self._inc_index = len(operations) - 1
995 operations.append({"op": "mutate",
996 "table": self._inc_row._table.name,
997 "where": self._substitute_uuids(
998 _where_uuid_equals(self._inc_row.uuid)),
999 "mutations": [[self._inc_column, "+=", 1]]})
1000 operations.append({"op": "select",
1001 "table": self._inc_row._table.name,
1002 "where": self._substitute_uuids(
1003 _where_uuid_equals(self._inc_row.uuid)),
1004 "columns": [self._inc_column]})
1008 operations.append({"op": "comment",
1009 "comment": "\n".join(self._comments)})
1013 operations.append({"op": "abort"})
1016 self._status = Transaction.UNCHANGED
1018 msg = ovs.jsonrpc.Message.create_request("transact", operations)
1019 self._request_id = msg.id
1020 if not self.idl._session.send(msg):
1021 self.idl._outstanding_txns[self._request_id] = self
1022 self._status = Transaction.INCOMPLETE
1024 self._status = Transaction.TRY_AGAIN
1026 self.__disassemble()
1029 def commit_block(self):
1030 """Attempts to commit this transaction, blocking until the commit
1031 either succeeds or fails. Returns the final commit status, which may
1032 be any Transaction.* value other than Transaction.INCOMPLETE.
1034 This function calls Idl.run() on this transaction'ss IDL, so it may
1035 cause Idl.change_seqno to change."""
1037 status = self.commit()
1038 if status != Transaction.INCOMPLETE:
1043 poller = ovs.poller.Poller()
1044 self.idl.wait(poller)
1048 def get_increment_new_value(self):
1049 """Returns the final (incremented) value of the column in this
1050 transaction that was set to be incremented by Row.increment. This
1051 transaction must have committed successfully."""
1052 assert self._status == Transaction.SUCCESS
1053 return self._inc_new_value
1056 """Aborts this transaction. If Transaction.commit() has already been
1057 called then the transaction might get committed anyhow."""
1058 self.__disassemble()
1059 if self._status in (Transaction.UNCOMMITTED,
1060 Transaction.INCOMPLETE):
1061 self._status = Transaction.ABORTED
1063 def get_error(self):
1064 """Returns a string representing this transaction's current status,
1065 suitable for use in log messages."""
1066 if self._status != Transaction.ERROR:
1067 return Transaction.status_to_string(self._status)
1071 return "no error details available"
1073 def __set_error_json(self, json):
1074 if self._error is None:
1075 self._error = ovs.json.to_string(json)
1077 def get_insert_uuid(self, uuid):
1078 """Finds and returns the permanent UUID that the database assigned to a
1079 newly inserted row, given the UUID that Transaction.insert() assigned
1080 locally to that row.
1082 Returns None if 'uuid' is not a UUID assigned by Transaction.insert()
1083 or if it was assigned by that function and then deleted by Row.delete()
1084 within the same transaction. (Rows that are inserted and then deleted
1085 within a single transaction are never sent to the database server, so
1086 it never assigns them a permanent UUID.)
1088 This transaction must have completed successfully."""
1089 assert self._status in (Transaction.SUCCESS,
1090 Transaction.UNCHANGED)
1091 inserted_row = self._inserted_rows.get(uuid)
1093 return inserted_row.real
1096 def _increment(self, row, column):
1097 assert not self._inc_row
1099 self._inc_column = column
1101 def _fetch(self, row, column_name):
1102 self._fetch_requests.append({"row": row, "column_name": column_name})
1104 def _write(self, row, column, datum):
1105 assert row._changes is not None
1109 # If this is a write-only column and the datum being written is the
1110 # same as the one already there, just skip the update entirely. This
1111 # is worth optimizing because we have a lot of columns that get
1112 # periodically refreshed into the database but don't actually change
1115 # We don't do this for read/write columns because that would break
1116 # atomicity of transactions--some other client might have written a
1117 # different value in that column since we read it. (But if a whole
1118 # transaction only does writes of existing values, without making any
1119 # real changes, we will drop the whole transaction later in
1120 # ovsdb_idl_txn_commit().)
1121 if (not column.alert and row._data and
1122 row._data.get(column.name) == datum):
1123 new_value = row._changes.get(column.name)
1124 if new_value is None or new_value == datum:
1127 txn._txn_rows[row.uuid] = row
1128 row._changes[column.name] = datum.copy()
1130 def insert(self, table, new_uuid=None):
1131 """Inserts and returns a new row in 'table', which must be one of the
1132 ovs.db.schema.TableSchema objects in the Idl's 'tables' dict.
1134 The new row is assigned a provisional UUID. If 'uuid' is None then one
1135 is randomly generated; otherwise 'uuid' should specify a randomly
1136 generated uuid.UUID not otherwise in use. ovsdb-server will assign a
1137 different UUID when 'txn' is committed, but the IDL will replace any
1138 uses of the provisional UUID in the data to be to be committed by the
1139 UUID assigned by ovsdb-server."""
1140 assert self._status == Transaction.UNCOMMITTED
1141 if new_uuid is None:
1142 new_uuid = uuid.uuid4()
1143 row = Row(self.idl, table, new_uuid, None)
1144 table.rows[row.uuid] = row
1145 self._txn_rows[row.uuid] = row
1148 def _process_reply(self, msg):
1149 if msg.type == ovs.jsonrpc.Message.T_ERROR:
1150 self._status = Transaction.ERROR
1151 elif type(msg.result) not in (list, tuple):
1153 vlog.warn('reply to "transact" is not JSON array')
1162 # This isn't an error in itself but indicates that some
1163 # prior operation failed, so make sure that we know about
1166 elif type(op) == dict:
1167 error = op.get("error")
1168 if error is not None:
1169 if error == "timed out":
1171 elif error == "not owner":
1173 elif error == "aborted":
1177 self.__set_error_json(op)
1180 self.__set_error_json(op)
1182 vlog.warn("operation reply is not JSON null or object")
1184 if not soft_errors and not hard_errors and not lock_errors:
1185 if self._inc_row and not self.__process_inc_reply(ops):
1187 if self._fetch_requests:
1188 if self.__process_fetch_reply(ops):
1189 self.idl.change_seqno += 1
1193 for insert in self._inserted_rows.itervalues():
1194 if not self.__process_insert_reply(insert, ops):
1198 self._status = Transaction.ERROR
1200 self._status = Transaction.NOT_LOCKED
1202 self._status = Transaction.TRY_AGAIN
1204 self._status = Transaction.SUCCESS
1207 def __check_json_type(json, types, name):
1210 vlog.warn("%s is missing" % name)
1212 elif type(json) not in types:
1214 vlog.warn("%s has unexpected type %s" % (name, type(json)))
1219 def __process_fetch_reply(self, ops):
1221 for fetch_request in self._fetch_requests:
1222 row = fetch_request["row"]
1223 column_name = fetch_request["column_name"]
1224 index = fetch_request["index"]
1228 fetched_rows = select.get("rows")
1229 if not Transaction.__check_json_type(fetched_rows, (list, tuple),
1230 '"select" reply "rows"'):
1232 if len(fetched_rows) != 1:
1234 vlog.warn('"select" reply "rows" has %d elements '
1235 'instead of 1' % len(fetched_rows))
1237 fetched_row = fetched_rows[0]
1238 if not Transaction.__check_json_type(fetched_row, (dict,),
1239 '"select" reply row'):
1242 column = table.columns.get(column_name)
1243 datum_json = fetched_row.get(column_name)
1244 datum = ovs.db.data.Datum.from_json(column.type, datum_json)
1246 row._data[column_name] = datum
1251 def __process_inc_reply(self, ops):
1252 if self._inc_index + 2 > len(ops):
1254 vlog.warn("reply does not contain enough operations for "
1255 "increment (has %d, needs %d)" %
1256 (len(ops), self._inc_index + 2))
1258 # We know that this is a JSON object because the loop in
1259 # __process_reply() already checked.
1260 mutate = ops[self._inc_index]
1261 count = mutate.get("count")
1262 if not Transaction.__check_json_type(count, (int, long),
1263 '"mutate" reply "count"'):
1267 vlog.warn('"mutate" reply "count" is %d instead of 1' % count)
1270 select = ops[self._inc_index + 1]
1271 rows = select.get("rows")
1272 if not Transaction.__check_json_type(rows, (list, tuple),
1273 '"select" reply "rows"'):
1277 vlog.warn('"select" reply "rows" has %d elements '
1278 'instead of 1' % len(rows))
1281 if not Transaction.__check_json_type(row, (dict,),
1282 '"select" reply row'):
1284 column = row.get(self._inc_column)
1285 if not Transaction.__check_json_type(column, (int, long),
1286 '"select" reply inc column'):
1288 self._inc_new_value = column
1291 def __process_insert_reply(self, insert, ops):
1292 if insert.op_index >= len(ops):
1294 vlog.warn("reply does not contain enough operations "
1295 "for insert (has %d, needs %d)"
1296 % (len(ops), insert.op_index))
1299 # We know that this is a JSON object because the loop in
1300 # __process_reply() already checked.
1301 reply = ops[insert.op_index]
1302 json_uuid = reply.get("uuid")
1303 if not Transaction.__check_json_type(json_uuid, (tuple, list),
1304 '"insert" reply "uuid"'):
1308 uuid_ = ovs.ovsuuid.from_json(json_uuid)
1311 vlog.warn('"insert" reply "uuid" is not a JSON UUID')
1318 class SchemaHelper(object):
1319 """IDL Schema helper.
1321 This class encapsulates the logic required to generate schemas suitable
1322 for creating 'ovs.db.idl.Idl' objects. Clients should register columns
1323 they are interested in using register_columns(). When finished, the
1324 get_idl_schema() function may be called.
1326 The location on disk of the schema used may be found in the
1327 'schema_location' variable."""
1329 def __init__(self, location=None, schema_json=None):
1330 """Creates a new Schema object.
1332 'location' file path to ovs schema. None means default location
1333 'schema_json' schema in json preresentation in memory
1336 if location and schema_json:
1337 raise ValueError("both location and schema_json can't be "
1338 "specified. it's ambiguous.")
1339 if schema_json is None:
1340 if location is None:
1341 location = "%s/vswitch.ovsschema" % ovs.dirs.PKGDATADIR
1342 schema_json = ovs.json.from_file(location)
1344 self.schema_json = schema_json
1349 def register_columns(self, table, columns, readonly=[]):
1350 """Registers interest in the given 'columns' of 'table'. Future calls
1351 to get_idl_schema() will include 'table':column for each column in
1352 'columns'. This function automatically avoids adding duplicate entries
1354 A subset of 'columns' can be specified as 'readonly'. The readonly
1355 columns are not replicated but can be fetched on-demand by the user
1358 'table' must be a string.
1359 'columns' must be a list of strings.
1360 'readonly' must be a list of strings.
1363 assert type(table) is str
1364 assert type(columns) is list
1366 columns = set(columns) | self._tables.get(table, set())
1367 self._tables[table] = columns
1368 self._readonly[table] = readonly
1370 def register_table(self, table):
1371 """Registers interest in the given all columns of 'table'. Future calls
1372 to get_idl_schema() will include all columns of 'table'.
1374 'table' must be a string
1376 assert type(table) is str
1377 self._tables[table] = set() # empty set means all columns in the table
1379 def register_all(self):
1380 """Registers interest in every column of every table."""
1383 def get_idl_schema(self):
1384 """Gets a schema appropriate for the creation of an 'ovs.db.id.IDL'
1385 object based on columns registered using the register_columns()
1388 schema = ovs.db.schema.DbSchema.from_json(self.schema_json)
1389 self.schema_json = None
1393 for table, columns in self._tables.iteritems():
1394 schema_tables[table] = (
1395 self._keep_table_columns(schema, table, columns))
1397 schema.tables = schema_tables
1398 schema.readonly = self._readonly
1401 def _keep_table_columns(self, schema, table_name, columns):
1402 assert table_name in schema.tables
1403 table = schema.tables[table_name]
1406 # empty set means all columns in the table
1410 for column_name in columns:
1411 assert type(column_name) is str
1412 assert column_name in table.columns
1414 new_columns[column_name] = table.columns[column_name]
1416 table.columns = new_columns