def upgrade_messages(update_comments=True, update_messages=True, update_trees=True):
    from r2.lib.db import queries
    from r2.lib import comment_tree, cache
    from r2.models import Account
    from pylons import app_globals as g

    accounts = set()

    def batch_fn(items):
        g.reset_caches()
        return items

    if update_messages or update_trees:
        q = Message._query(Message.c.new == True, sort=desc("_date"), data=True)
        for m in fetch_things2(q, batch_fn=batch_fn):
            print m, m._date
            if update_messages:
                accounts = accounts | queries.set_unread(m, m.new)
            else:
                accounts.add(m.to_id)
    if update_comments:
        q = Comment._query(Comment.c.new == True, sort=desc("_date"))
        q._filter(Comment.c._id < 26152162676)

        for m in fetch_things2(q, batch_fn=batch_fn):
            print m, m._date
            queries.set_unread(m, True)

    print "Precomputing comment trees for %d accounts" % len(accounts)

    for i, a in enumerate(accounts):
        if not isinstance(a, Account):
            a = Account._byID(a)
        print i, a
        comment_tree.user_messages(a)

 def get_tree(self):
     if self.parent:
         return conversation(self.user, self.parent)
     return user_messages(self.user)