DisconnectionError not raised when TCP errors messup underlying PostgreSQL db connection

[Stuart Bishop]

Per Bug #1000805, it is possible for the following exception to be raised when issuing a query:

psycopg2.OperationalError: could not send data to server: Connection timed out

While this is probably a network issue that needs fixing, Storm still should detect that this is a disconnection error and reraise it as a DisconnectionError, so the store is put into the 'will reconnect' state.

[Stuart Bishop (stub)]

Storm already catches all DatabaseError subclasses (including OperationalError) that set the psycopg2 connection object's closed attribute. So for the bug's situation to happen, I think it means psycopg2 is not flagging the connection as closed if this TCP failure happens.

[Stuart Bishop (stub)]

Need to verify that this is really happening.

[Stuart Bishop (stub)]

It looks like we don't reraise failures when constructing Stores as DisconnectionErrors.

stub@aargh:~/lp/replication$ python
Python 2.7.3 (default, Aug 1 2012, 05:14:39)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from storm.locals import *
>>> db = create_database('postgres://localhost:6666/whatever')
>>> from storm.exceptions import DisconnectionError
>>> try:
... store = Store(db)
... except DisconnectionError:
... print 'storm exception'
...
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/usr/local/lib/python2.7/dist-packages/storm-0.19-py2.7-linux-x86_64.egg/storm/store.py", line 73, in __init__
    self._connection = database.connect(self._event)
  File "/usr/local/lib/python2.7/dist-packages/storm-0.19-py2.7-linux-x86_64.egg/storm/database.py", line 410, in connect
    return self.connection_factory(self, event)
  File "/usr/local/lib/python2.7/dist-packages/storm-0.19-py2.7-linux-x86_64.egg/storm/database.py", line 185, in __init__
    self._raw_connection = self._database.raw_connect()
  File "/usr/local/lib/python2.7/dist-packages/storm-0.19-py2.7-linux-x86_64.egg/storm/databases/postgres.py", line 329, in raw_connect
    raw_connection = psycopg2.connect(self._dsn)
  File "/usr/lib/python2.7/dist-packages/psycopg2/__init__.py", line 179, in connect
    connection_factory=connection_factory, async=async)
psycopg2.OperationalError: could not connect to server: Connection refused
 Is the server running on host "localhost" (127.0.0.1) and accepting
 TCP/IP connections on port 6666?

[Stuart Bishop (stub)]

The problem seems to be we are opening the connection in the constructor rather than deferring this until the Store is used. I think it is safe to wrap the raw_connect with _check_disconnect

[Sidnei da Silva (sidnei)]

Linked possibly related fix for an error that happens at runtime (instead of at connection construction). Please mark as fix released if it fixes the issue.