On Fri, 22 Jan 2010 17:17:27 -0600 Anthony Liguori <anth...@codemonkey.ws> 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<a...@us.ibm.com> > > To: Anthony Liguori<anth...@codemonkey.ws> > > cc: Luiz Capitulino<lcapitul...@redhat.com> > > 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.
