Re: [Qemu-devel] Dropping the MONITOR_CMD_ASYNC

[Alon Levy]

On Thu, Dec 08, 2011 at 05:45:44PM -0200, Luiz Capitulino wrote:
> Hi there,
> 
> I'm about to completely drop the MONITOR_CMD_ASYNC API, but it turns out that
> the command client_migrate_info uses it. That's a legacy interface and has to
> be dropped, no command should be using it...
> 
> Something tells me that if I just drop it (and change the command to use the
> regular interface), bad things will happen. Am I right? :)
> 

The monitor command client_migrate_info needs to complete after getting
an ACK message from the currently connected spice client (this is the
only case where this is required - if there is no client then the
MONITOR_CMD_ASYNC API won't be used). This in turn requires the main
thread to perform select and call the callback that will process this
ACK. That's why the MONITOR_CMD_ASYNC API was used.

I'm not aware of any other way to do this, I'll be glad for any help
here. Also, I understand this is not what is not true async, since one
would expect a true async interface to support multiple in flight
monitor commands. If there is any ETA or existing way to do this we
could change the implementation of client_migrate_info.

Alon