instance.py 文件源码

def save_model(self, request, obj, form, change):
        """
        Automatically detect/populate several fields before saving instance

        Since we're defining what is (hopefully) an existing structure,
        we should be able to auto-detect several elements from the database
        itself. There can also a backend monitor on each server that will
        keep these values updated, but bootstrapping is always best.

        Autodetected fields:
          * is_online
          * master
          * version
        """

        # First, check the online status. We want this to be as fresh as
        # possible, so we might as well grab it now.

        obj.is_online = False

        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        check = sock.connect_ex((obj.server.hostname, obj.herd.db_port))

        if check == 0:
            obj.is_online = True

        # Then, since herds are organized such that each herd follows a single
        # primary node, we can auto-declare that this is a replica or not.
        # If we search and find a primary for this herd, that instance will
        # become our master.

        util = PGUtility(obj)
        obj.master = util.get_herd_primary()
        obj.version = util.get_version()

        if obj.master and not obj.version:
            obj.version = obj.master.version

        # Save now that we've hijacked everything.

        obj.save()

        # Attempt to initialize the instance. This only works if the instance
        # doesn't already exist. It's also optional, so don't derail the save
        # just because it didn't fully work.

        try:
            util.init_missing()
        except Exception, e:
            self.message_user(request, "Instance init: %s" % str(e),
                messages.WARNING
            )