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Viewing changes to nova/db/sqlalchemy/session.py

  • Committer: Package Import Robot
  • Author(s): Chuck Short
  • Date: 2012-08-16 14:04:11 UTC
  • mto: This revision was merged to the branch mainline in revision 84.
  • Revision ID: package-import@ubuntu.com-20120816140411-0mr4n241wmk30t9l
Tags: upstream-2012.2~f3
Import upstream version 2012.2~f3

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nova/db/sqlalchemy/session.py
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"""Session Handling for SQLAlchemy backend."""
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import re
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import time
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from sqlalchemy.exc import DisconnectionError, OperationalError
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    return session
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class SynchronousSwitchListener(sqlalchemy.interfaces.PoolListener):
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def synchronous_switch_listener(dbapi_conn, connection_rec):
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    """Switch sqlite connections to non-synchronous mode"""
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    def connect(self, dbapi_con, con_record):
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        dbapi_con.execute("PRAGMA synchronous = OFF")
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class MySQLPingListener(object):
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    dbapi_conn.execute("PRAGMA synchronous = OFF")
 
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def ping_listener(dbapi_conn, connection_rec, connection_proxy):
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    """
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    Ensures that MySQL connections checked out of the
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    pool are alive.
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    Borrowed from:
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    http://groups.google.com/group/sqlalchemy/msg/a4ce563d802c929f
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    """
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    def checkout(self, dbapi_con, con_record, con_proxy):
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        try:
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            dbapi_con.cursor().execute('select 1')
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        except dbapi_con.OperationalError, ex:
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            if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
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                LOG.warn('Got mysql server has gone away: %s', ex)
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                raise DisconnectionError("Database server went away")
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            else:
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                raise
 
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    try:
 
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        dbapi_conn.cursor().execute('select 1')
 
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    except dbapi_conn.OperationalError, ex:
 
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        if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
 
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            LOG.warn('Got mysql server has gone away: %s', ex)
 
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            raise DisconnectionError("Database server went away")
 
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        else:
 
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            raise
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def is_db_connection_error(args):
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    return False
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def regexp(expr, item):
 
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    reg = re.compile(expr)
 
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    return reg.search(unicode(item)) is not None
 
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class AddRegexFactory(sqlalchemy.interfaces.PoolListener):
 
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    def connect(delf, dbapi_con, con_record):
 
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        dbapi_con.create_function('REGEXP', 2, regexp)
 
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def get_engine():
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    """Return a SQLAlchemy engine."""
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    global _ENGINE
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            if FLAGS.sql_connection == "sqlite://":
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                engine_args["poolclass"] = StaticPool
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                engine_args["connect_args"] = {'check_same_thread': False}
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                engine_args['listeners'] = [AddRegexFactory()]
 
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        _ENGINE = sqlalchemy.create_engine(FLAGS.sql_connection, **engine_args)
 
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        if 'mysql' in connection_dict.drivername:
 
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            sqlalchemy.event.listen(_ENGINE, 'checkout', ping_listener)
 
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        elif "sqlite" in connection_dict.drivername:
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            if not FLAGS.sqlite_synchronous:
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                engine_args["listeners"] = [SynchronousSwitchListener()]
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        if 'mysql' in connection_dict.drivername:
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            engine_args['listeners'] = [MySQLPingListener()]
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        _ENGINE = sqlalchemy.create_engine(FLAGS.sql_connection, **engine_args)
 
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                sqlalchemy.event.listen(_ENGINE, 'connect',
 
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                                        synchronous_switch_listener)
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        if (FLAGS.sql_connection_trace and
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                _ENGINE.dialect.dbapi.__name__ == 'MySQLdb'):