Synnefo » Pithos

# Copyright 2011 GRNET S.A. All rights reserved.

# 

# Redistribution and use in source and binary forms, with or

# without modification, are permitted provided that the following

# conditions are met:

# 

#   1. Redistributions of source code must retain the above

#      copyright notice, this list of conditions and the following

#      disclaimer.

# 

#   2. Redistributions in binary form must reproduce the above

#      copyright notice, this list of conditions and the following

#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

# 

# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

# POSSIBILITY OF SUCH DAMAGE.

# 

# The views and conclusions contained in the software and

# documentation are those of the authors and should not be

# interpreted as representing official policies, either expressed

# or implied, of GRNET S.A.

from sqlalchemy import create_engine

from sqlalchemy.pool import NullPool

from sqlalchemy.interfaces import PoolListener

class DBWrapper(object):

    """Database connection wrapper."""

    def __init__(self, db):

        if db.startswith('sqlite://'):

            class ForeignKeysListener(PoolListener):

                def connect(self, dbapi_con, con_record):

                    db_cursor = dbapi_con.execute('pragma foreign_keys=ON')

            self.engine = create_engine(db, connect_args={'check_same_thread': False}, poolclass=NullPool, listeners=[ForeignKeysListener()])

        else:

            self.engine = create_engine(db)

        #self.engine.echo = True

        self.conn = self.engine.connect()

        self.trans = None

    def execute(self):

        self.trans = self.conn.begin()

    def commit(self):

        self.trans.commit()

        self.trans = None

    def rollback(self):

        self.trans.rollback()

        self.trans = None