From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NZOid-00055k-Hi for qemu-devel@nongnu.org; Mon, 25 Jan 2010 08:11:03 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NZOiZ-00055M-4M for qemu-devel@nongnu.org; Mon, 25 Jan 2010 08:11:03 -0500 Received: from [199.232.76.173] (port=50415 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NZOiY-00055J-Tm for qemu-devel@nongnu.org; Mon, 25 Jan 2010 08:10:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1646) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NZOiY-0001wq-5A for qemu-devel@nongnu.org; Mon, 25 Jan 2010 08:10:58 -0500 Date: Mon, 25 Jan 2010 11:10:49 -0200 From: Luiz Capitulino Message-ID: <20100125111049.0f0e0d1d@doriath> In-Reply-To: <4B5A3207.5030105@codemonkey.ws> References: <1264187031.2861.13.camel@aglitke> <4B5A3207.5030105@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [RFC] New API for asynchronous monitor commands List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Markus Armbruster , Avi Kivity , qemu-devel@nongnu.org, Adam Litke On Fri, 22 Jan 2010 17:17:27 -0600 Anthony Liguori wrote: > On 01/22/2010 01:03 PM, Adam Litke wrote: > > Qemu has a number of commands that can operate asynchronously (savevm, migrate, > > etc) and it will be getting more. For these commands, the user monitor needs > > to be suspended, but QMP monitors could continue to to accept other commands. > > This patch introduces a new command API that isolates the details of handling > > different monitor types from the actual command execution. > > > > A monitor command can use this API by implementing the mhandler.cmd_async > > handler (or info_async if appropriate). This function is responsible for > > submitting the command and does not return any data although it may raise > > errors. When the command completes, the QMPCompletion callback should be > > invoked with its opaque data and the command result. > > > > The process for submitting and completing an asynchronous command is different > > for QMP and user monitors. A user monitor must be suspended at submit time and > > resumed at completion time. The user_print() function must be passed to the > > QMPCompletion callback so the result can be displayed properly. QMP monitors > > are simpler. No submit time setup is required. When the command completes, > > monitor_protocol_emitter() writes the result in JSON format. > > > > This API can also be used to implement synchronous commands. In this case, the > > cmd_async handler should immediately call the QMPCompletion callback. It is my > > hope that this new interface will work for all commands, leading to a > > drastically simplified monitor.c once all commands are ported. > > > > Thanks to Anthony for helping me out with the initial design. > > > > Signed-off-by: Adam Litke > > To: Anthony Liguori > > cc: Luiz Capitulino > > Cc: qemu-devel@nongnu.org > > > > I like this a lot and I'd like to see us remove cmd_new in place of > cmd_async. The conversion is pretty easy since we just have to add a > cb(ret_data) to the end of synchronous functions. > > Luiz/Markus/Avi, what do ya'll think? I like it too, but I don't like the idea of using it for synchronous commands, I explained the reasons in the patch itself.