txpostgres pool.py

class ConnectionPool(txpostgres.ConnectionPool):
    """A txpostgres ConnectionPool that renders sqlalchemy queries

    This is so you can pass a sqlalchemy Query object to .runQuery
    and .runOperation. It will render it using the postgresql sqlalchemy
    dialect.
    """
    def __init__(self, **kwargs):
        kwargs.setdefault('cursor_factory', NamedTupleCursor)
        self._sqla_dialect = dialect()
        super(ConnectionPool, self).__init__(None, **kwargs)

    def runQuery(self, query, params=None):
        query, params = getQueryWithParams(self._sqla_dialect, query, params)
        return super(ConnectionPool, self).runQuery(query, params)

    def runOperation(self, query, params=None):
        query, params = getQueryWithParams(self._sqla_dialect, query, params)
        return super(ConnectionPool, self).runOperation(query, params)

    def start(self, *a, **kw):
        started = Deferred()

        def _waitForStart():
            return started

        def _cbStarted(_):
            started.callback(None)
            return self

        for i in range(self.min):
            self._semaphore.run(_waitForStart)

        return (super(ConnectionPool, self).start(*a, **kw)
                .addCallback(_cbStarted))