source: trunk/Monitoring/smon/db.py

# -*- coding: ISO-8859-1 -*-

##################################
#  @program        smon
#  @description    simulation monitor
#  @copyright      Copyright “(c)2009 Centre National de la Recherche Scientifique CNRS. 
#                             All Rights Reserved”
#  @svn_file       $Id: db.py 2585 2013-03-24 04:09:22Z jripsl $
#  @version        $Rev: 2585 $
#  @lastrevision   $Date: 2013-03-24 05:09:22 +0100 (Sun, 24 Mar 2013) $
#  @license        CeCILL (http://dods.ipsl.jussieu.fr/jripsl/smon/LICENSE)
##################################

from logger import *

class CDatabase():
        _conn=None

        @classmethod
        def connect(self):

                # When a database is accessed by multiple connections, and one of the processes
                # modifies the database, the SQLite database is locked until that transaction is
                # committed. The timeout parameter specifies how long the connection should wait
                # for the lock to go away until raising an exception. The default for the timeout
                # parameter is 5.0 (five seconds).
                #
                # more info here => http://www.sqlite.org/faq.html#q5
                #
                # we increase the timeout so we are able to use sqlite3 to run manual
                # query without stopping the daemon
                #
                l__timeout=120 # 2 mn

                # Note
                #  by default, sqlite is in autocommit mode,
                #  but the sqlite3 python module is *not* in autocommit mode by default
                #  we don't want autocommit mode, so we leave it at its default, which will result in a plain "BEGIN" statement
                #  (If you want autocommit mode, then set isolation_level to None)

                # open connection
                self._conn=sqlite3.connect(self.get_DB_name(),l__timeout)
                self._conn.row_factory=sqlite3.Row # this is for "by name" colums indexing

                self.createTables()

        @classmethod
        def get_DB_name(self):
                return SMON.dbfile

        @classmethod
        def disconnect(self):
                if self.isConnected():
                        self._conn.close()

                self._conn=None

        @classmethod
        def isConnected(self):
                if (self._conn==None):
                        return False
                else:
                        return True

        @classmethod
        def createTables(self):
                c=self._conn.cursor()

                c.execute("create table if not exists message (id INTEGER PRIMARY KEY, name TEXT, timestamp TEXT, nested_level INT, simulation_id INT")
                c.execute("create index if not exists idx_message_1 on message (timestamp)")

                self._conn.commit()
                c.close()