How to use the ovs.db.idl.Transaction function in ovs

def idl_set(idl, commands, step):
    txn = ovs.db.idl.Transaction(idl)
    increment = False
    fetch_cmds = []
    events = []
    for command in commands.split(','):
        words = command.split()
        name = words[0]
        args = words[1:]

        if name == "notifytest":
            name = args[0]
            args = args[1:]
            old_notify = idl.notify

            def notify(event, row, updates=None):
                if updates:
                    upcol = list(updates._data.keys())[0]

def do_commit(self):
        self.start_time = time.time()
        attempts = 0
        while True:
            if attempts > 0 and self.timeout_exceeded():
                raise RuntimeError(_("OVS transaction timed out"))
            attempts += 1
            # TODO(twilson) Make sure we don't loop longer than vsctl_timeout
            txn = idl.Transaction(self.api.idl)
            self.pre_commit(txn)
            for i, command in enumerate(self.commands):
                LOG.debug("Running txn command(idx=%(idx)s): %(cmd)s",
                          {'idx': i, 'cmd': command})
                try:
                    command.run_idl(txn)
                except Exception:
                    with excutils.save_and_reraise_exception() as ctx:
                        txn.abort()
                        if not self.check_error:
                            ctx.reraise = False
            status = txn.commit_block()
            if status == txn.TRY_AGAIN:
                LOG.debug("OVSDB transaction returned TRY_AGAIN, retrying")
                continue
            elif status == txn.ERROR:

if self.wait_for_reload and status == idl.Transaction.SUCCESS:
            next_cfg = self.txn.get_increment_new_value()

        # TODO:XXX
        # if status in (idl.Transaction.UNCHANGED, idl.Transaction.SUCCESS):
        #     for command in commands:
        #         if not command.post_func:
        #             continue
        #         ctx = VSCtlContext(idl_, txn, self.ovs)
        #         command.post_func(ctx)
        #         ctx.done()

        txn_ = self.txn
        self.txn = None

        if status in (idl.Transaction.UNCOMMITTED, idl.Transaction.INCOMPLETE):
            not_reached()
        elif status == idl.Transaction.ABORTED:
            vsctl_fatal('transaction aborted')
        elif status == idl.Transaction.UNCHANGED:
            LOG.debug('unchanged')
        elif status == idl.Transaction.SUCCESS:
            LOG.debug('success')
        elif status == idl.Transaction.TRY_AGAIN:
            return False
        elif status == idl.Transaction.ERROR:
            vsctl_fatal('transaction error: %s' % txn_.get_error())
        elif status == idl.Transaction.NOT_LOCKED:
            vsctl_fatal('database not locked')
        else:
            not_reached()

def _do_vsctl(self, idl_, commands):
        txn = idl.Transaction(idl_)
        self.txn = txn
        if self.dry_run:
            txn.dry_run = True

        txn.add_comment('ovs-vsctl')  # TODO:XXX add operation name. args
        ovs_rows = idl_.tables[vswitch_idl.OVSREC_TABLE_OPEN_VSWITCH].rows
        if ovs_rows:
            ovs_ = ovs_rows.values()[0]
        else:
            # XXX add verification that table is empty
            ovs_ = txn.insert(
                idl_.tables[vswitch_idl.OVSREC_TABLE_OPEN_VSWITCH])

        if self.wait_for_reload:
            ovs_.increment(vswitch_idl.OVSREC_OPEN_VSWITCH_COL_NEXT_CFG)

#             continue
        #         ctx = VSCtlContext(idl_, txn, self.ovs)
        #         command.post_func(ctx)
        #         ctx.done()

        txn_ = self.txn
        self.txn = None
        txn = None

        if status in (idl.Transaction.UNCOMMITTED, idl.Transaction.INCOMPLETE):
            not_reached()
        elif status == idl.Transaction.ABORTED:
            vsctl_fatal('transaction aborted')
        elif status in (idl.Transaction.UNCHANGED, idl.Transaction.SUCCESS):
            pass
        elif status == idl.Transaction.TRY_AGAIN:
            return False
        elif status == idl.Transaction.ERROR:
            vsctl_fatal('transaction error: %s' % txn_.get_error())
        elif status == idl.Transaction.NOT_LOCKED:
            vsctl_fatal('database not locked')
        else:
            not_reached()

        if self.wait_for_reload and status != idl.Transaction.UNCHANGED:
            while True:
                idl_.run()
                if (ovs_.cur_cfg >= next_cfg):
                    break
                self._idl_block(idl_)

        return True

# TODO:XXX
        # if status in (idl.Transaction.UNCHANGED, idl.Transaction.SUCCESS):
        #     for command in commands:
        #         if not command.post_func:
        #             continue
        #         ctx = VSCtlContext(idl_, txn, self.ovs)
        #         command.post_func(ctx)
        #         ctx.done()

        txn_ = self.txn
        self.txn = None
        txn = None

        if status in (idl.Transaction.UNCOMMITTED, idl.Transaction.INCOMPLETE):
            not_reached()
        elif status == idl.Transaction.ABORTED:
            vsctl_fatal('transaction aborted')
        elif status in (idl.Transaction.UNCHANGED, idl.Transaction.SUCCESS):
            pass
        elif status == idl.Transaction.TRY_AGAIN:
            return False
        elif status == idl.Transaction.ERROR:
            vsctl_fatal('transaction error: %s' % txn_.get_error())
        elif status == idl.Transaction.NOT_LOCKED:
            vsctl_fatal('database not locked')
        else:
            not_reached()

        if self.wait_for_reload and status != idl.Transaction.UNCHANGED:
            while True:
                idl_.run()
                if (ovs_.cur_cfg >= next_cfg):

# TODO:XXX
        # if status in (idl.Transaction.UNCHANGED, idl.Transaction.SUCCESS):
        #     for command in commands:
        #         if not command.post_func:
        #             continue
        #         ctx = VSCtlContext(idl_, txn, self.ovs)
        #         command.post_func(ctx)
        #         ctx.done()

        txn_ = self.txn
        self.txn = None

        if status in (idl.Transaction.UNCOMMITTED, idl.Transaction.INCOMPLETE):
            not_reached()
        elif status == idl.Transaction.ABORTED:
            vsctl_fatal('transaction aborted')
        elif status == idl.Transaction.UNCHANGED:
            LOG.debug('unchanged')
        elif status == idl.Transaction.SUCCESS:
            LOG.debug('success')
        elif status == idl.Transaction.TRY_AGAIN:
            return False
        elif status == idl.Transaction.ERROR:
            vsctl_fatal('transaction error: %s' % txn_.get_error())
        elif status == idl.Transaction.NOT_LOCKED:
            vsctl_fatal('database not locked')
        else:
            not_reached()

        if self.wait_for_reload and status != idl.Transaction.UNCHANGED:
            while True:

def _transaction(self):
        req = self._txn_q.popleft()
        txn = idl.Transaction(self._idl)

        uuids = req.func(self._idl.tables, txn.insert)
        status = txn.commit_block()

        insert_uuids = {}
        err_msg = None

        if status in (idl.Transaction.SUCCESS,
                      idl.Transaction.UNCHANGED):
            if uuids:
                if isinstance(uuids, uuid.UUID):
                    insert_uuids[uuids] = txn.get_insert_uuid(uuids)

                else:
                    insert_uuids = dict((uuid, txn.get_insert_uuid(uuid))
                                        for uuid in uuids)