__init__.py 文件源码

def open(self):
        """Connect to the server.

        Takes an optional callback, or returns a Future that resolves to
        ``self`` when opened. This is convenient for checking at program
        startup time whether you can connect.

        .. doctest::

          >>> client = MotorClient()
          >>> # run_sync() returns the open client.
          >>> IOLoop.current().run_sync(client.open)
          MotorClient(MongoClient('localhost', 27017))

        ``open`` raises a :exc:`~pymongo.errors.ConnectionFailure` if it
        cannot connect, but note that auth failures aren't revealed until
        you attempt an operation on the open client.

        :Parameters:
         - `callback`: Optional function taking parameters (self, error)

        .. versionchanged:: 0.2
           :class:`MotorReplicaSetClient` now opens itself on demand, calling
           ``open`` explicitly is now optional.
        """
        yield self._ensure_connected(True)
        primary = self._get_member()
        if not primary:
            raise pymongo.errors.AutoReconnect('no primary is available')
        raise gen.Return(self)