From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51194) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VOd4N-0004Cz-2j for Qemu-devel@nongnu.org; Tue, 24 Sep 2013 20:35:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VOd4H-0003FL-2Q for Qemu-devel@nongnu.org; Tue, 24 Sep 2013 20:35:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9366) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VOd4G-0003FD-Qr for Qemu-devel@nongnu.org; Tue, 24 Sep 2013 20:35:00 -0400 Date: Tue, 24 Sep 2013 20:34:54 -0400 From: Luiz Capitulino Message-ID: <20130924203454.2901afc3@redhat.com> In-Reply-To: <20130924210729.20300.29270@loki> References: <1379832654-21722-1-git-send-email-wudxw@linux.vnet.ibm.com> <20130924190032.7651.74662@loki> <5241E444.4040606@redhat.com> <20130924210729.20300.29270@loki> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] Extend qemu-ga's 'guest-info' command to expose flag 'success-response' List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Roth Cc: Mark Wu , Qemu-devel@nongnu.org On Tue, 24 Sep 2013 16:07:29 -0500 Michael Roth wrote: > > >> +bool qmp_command_has_success_response(const char *name) > > >> +{ > > >> + QmpCommand *cmd; > > >> + > > >> + QTAILQ_FOREACH(cmd, &qmp_commands, node) { > > >> + if (strcmp(cmd->name, name) == 0) { > > >> + return cmd->options != QCO_NO_SUCCESS_RESP; > > > > cmd->options is a bitmask - it is feasible that we may add more QCO_NO_* > > flags in the future, at which point inequality is NOT correct. Rather, > > you want: > > > > return !(cmd->options & QCO_NO_SUCCESS_RESP); Good catch! IIRC I added cmd->options myself and didn't catch this... > > >> +++ b/qga/commands.c > > >> @@ -63,6 +63,8 @@ struct GuestAgentInfo *qmp_guest_info(Error **err) > > >> cmd_info = g_malloc0(sizeof(GuestAgentCommandInfo)); > > >> cmd_info->name = g_strdup(*cmd_list); > > >> cmd_info->enabled = qmp_command_is_enabled(cmd_info->name); > > >> + cmd_info->success_response = > > >> + qmp_command_has_success_response(cmd_info->name); > > > > This feels wasteful. Why are we doing an O(n) lookup for BOTH > > qmp_command_is_enabled AND qmp_command_has_success_response, in an O(n) > > loop over command names? That's O(n^2) in the number of commands. > > Better would be getting a list of QmpCommand* instead of a list of > > char*, and looking directly in each object, for O(n) computation of the > > results. > > Agreed, modifying qmp_get_command_list to return a list of QmpCommand > would be nicer. Rather than looking directly at the fields though I > think we should just fix up qmp_command_is_enabled() and friends to > take a QmpCommand arg instead of a char*. We already have > qmp_find_command to map char*->QmpCommand to support any cases where > we rely on cmd names. I agree and I thought the same thing when I reviewed the patch, but I didn't mind as Mark is just using what's already there.