Source code for gramps.gen.db.txn

#
# Gramps - a GTK+/GNOME based genealogy program
#
# Copyright (C) 2004-2006 Donald N. Allingham
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

"""
Exports the DbTxn class for managing Gramps transactions and the undo
database.
"""

#-------------------------------------------------------------------------
#
# Standard python modules
#
#-------------------------------------------------------------------------
from __future__ import print_function, with_statement

import sys
if sys.version_info[0] < 3:
    import cPickle as pickle
else:
    import pickle
import logging

from collections import defaultdict

#-------------------------------------------------------------------------
#
# Gramps modules
#
#-------------------------------------------------------------------------
from .dbconst import (DBLOGNAME, TXNADD, TXNUPD, TXNDEL)

_LOG = logging.getLogger(DBLOGNAME)


#-------------------------------------------------------------------------
#
# Gramps transaction class
#
#-------------------------------------------------------------------------
[docs]class DbTxn(defaultdict): """ Define a group of database commits that define a single logical operation. """ __slots__ = ('msg', 'commitdb', 'db', 'batch', 'first', 'last', 'timestamp', '__dict__') def __enter__(self): """ Context manager entry method """ self.db.transaction_begin(self) return self def __exit__(self, exc_type, exc_val, exc_tb): """ Context manager exit method """ if exc_type is None: self.db.transaction_commit(self) else: self.db.transaction_abort(self) return False def __init__(self, msg, grampsdb, batch=False, **kwargs): """ Create a new transaction. The grampsdb should have transaction_begin/commit/abort methods, and a get_undodb method to store undo actions. A Transaction instance can be created directly, but it is advised to use a context to do this. Like this the user must not worry about calling the transaction_xx methods on the database. The grampsdb parameter is a reference to the DbWrite object to which this transaction will be applied. grampsdb.get_undodb() should return a list-like interface that stores the commit data. This could be a simple list, or a RECNO-style database object. The data structure used to handle the transactions (see the add method) is a Python dictionary where: key = (object type, transaction type) where: object type = the numeric type of an object. These are defined as PERSON_KEY = 0, FAMILY_KEY = 1, etc. as imported from dbconst. transaction type = a numeric representation of the type of transaction: TXNADD = 0, TXNUPD = 1, TXNDEL = 2 data = Python list where: list element = (handle, data) where: handle = handle (database key) of the object in the transaction data = pickled representation of the object """ defaultdict.__init__(self, list, {}) self.msg = msg self.commitdb = grampsdb.get_undodb() self.db = grampsdb self.batch = batch for key, value in kwargs.items(): setattr(self, key, value) self.first = None self.last = None self.timestamp = 0
[docs] def get_description(self): """ Return the text string that describes the logical operation performed by the Transaction. """ return self.msg
[docs] def set_description(self, msg): """ Set the text string that describes the logical operation performed by the Transaction. """ self.msg = msg
[docs] def add(self, obj_type, trans_type, handle, old_data, new_data): """ Add a commit operation to the Transaction. The obj_type is a constant that indicates what type of PrimaryObject is being added. The handle is the object's database handle, and the data is the tuple returned by the object's serialize method. """ self.last = self.commitdb.append( pickle.dumps((obj_type, trans_type, handle, old_data, new_data), 1)) if self.last is None: self.last = len(self.commitdb) -1 if self.first is None: self.first = self.last _LOG.debug('added to trans: %d %d %s' % (obj_type, trans_type, handle)) self[(obj_type, trans_type)] += [(handle, new_data)] return
[docs] def get_recnos(self, reverse=False): """ Return a list of record numbers associated with the transaction. While the list is an arbitrary index of integers, it can be used to indicate record numbers for a database. """ if self.first is None or self.last is None: return [] if not reverse: return range(self.first, self.last+1) else: return range(self.last, self.first-1, -1)
[docs] def get_record(self, recno): """ Return a tuple representing the PrimaryObject type, database handle for the PrimaryObject, and a tuple representing the data created by the object's serialize method. """ return pickle.loads(self.commitdb[recno])
def __len__(self): """ Return the number of commits associated with the Transaction. """ if self.first is None or self.last is None: return 0 return self.last - self.first + 1 # Test functions
[docs]def testtxn(): """ Test suite """ class FakeMap(dict): """Fake database map with just two methods""" def put(self, key, data): """Set a property""" super(FakeMap, self).__setitem__(key, data) def delete(self, key): """Delete a proptery""" super(FakeMap, self).__delitem__(key) class FakeDb: """Fake gramps database""" def __init__(self): self.person_map = FakeMap() self.family_map = FakeMap() self.event_map = FakeMap() self.reference_map = FakeMap() self.readonly = False self.env = None self.undodb = FakeCommitDb() def transaction_commit(self, transaction): """Commit the transaction to the undo database and cleanup.""" transaction.clear() self.undodb.commit(transaction) def emit(self, obj, value): """send signal""" pass class FakeCommitDb(list): """ Fake commit database""" def commit(self, transaction): """commit transaction to undo db""" pass def undo(self): """undo last transaction""" pass grampsdb = FakeDb() commitdb = grampsdb.undodb trans = DbTxn("Test Transaction", commitdb, grampsdb, batch=False) grampsdb.person_map.put('1', "data1") trans.add(0, TXNADD, '1', None, "data1") grampsdb.person_map.put('2', "data2") trans.add(0, TXNADD, '2', None, "data2") grampsdb.person_map.put('2', "data3") trans.add(0, TXNUPD, '2', None, "data3") grampsdb.person_map.delete('1') trans.add(0, TXNDEL, '1', None, None) print(trans) print(trans.get_description()) print(trans.set_description("new text")) print(trans.get_description()) for i in trans.get_recnos(): print(trans.get_record(i)) print(list(trans.get_recnos())) print(list(trans.get_recnos(reverse=True))) print(grampsdb.person_map)
if __name__ == '__main__': testtxn()