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# Copyright 2011-2012 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or
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# without modification, are permitted provided that the following
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# conditions are met:
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#
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#   1. Redistributions of source code must retain the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer.
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#
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#   2. Redistributions in binary form must reproduce the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer in the documentation and/or other materials
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#      provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and
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# documentation are those of the authors and should not be
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# interpreted as representing official policies, either expressed
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# or implied, of GRNET S.A.
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from sqlalchemy import Table, Column, String, MetaData
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from sqlalchemy.sql import select
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from sqlalchemy.exc import NoSuchTableError
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from dbworker import DBWorker
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def create_tables(engine):
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    metadata = MetaData()
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    columns = []
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    columns.append(Column('key', String(256), primary_key=True))
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    columns.append(Column('value', String(256)))
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    Table('config', metadata, *columns, mysql_engine='InnoDB')
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    metadata.create_all(engine)
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    return metadata.sorted_tables
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class Config(DBWorker):
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    """Config are properties holding persistent information about system state.
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    """
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    def __init__(self, **params):
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        DBWorker.__init__(self, **params)
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        try:
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            metadata = MetaData(self.engine)
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            self.config = Table('config', metadata, autoload=True)
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        except NoSuchTableError:
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            tables = create_tables(self.engine)
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            map(lambda t: self.__setattr__(t.name, t), tables)
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    def get_value(self, key):
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        """Return configuration value for key."""
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        s = select([self.config.c.value])
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        s = s.where(self.config.c.key == key)
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        r = self.conn.execute(s)
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        row = r.fetchone()
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        r.close()
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        if row:
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            return row[0]
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        return None
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    def set_value(self, key, value):
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        """Set a configuration entry.
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        """
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        s = self.config.insert()
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        r = self.conn.execute(s, key=key, value=value)
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        inserted_primary_key = r.inserted_primary_key[0]
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        r.close()
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        return inserted_primary_key