Re: [libvirt] [Qemu-devel] virDomainBlockJobAbort and block_job_cancel
On Wed, Dec 7, 2011 at 11:01 PM, Eric Blake <eblake(a)redhat.com> wrote:
On 12/07/2011 03:35 PM, Adam Litke wrote:
4) Ask Stefan to make the HMP monitor command synchronous, but only
expose the JSON command as asynchronous. After all, it is only HMP
where we can't wait for an event.
QEMU cannot do async commands, even for HMP. My QEMU patches used to
work because there is a broken async flag for monitor commands. I
didn't know it was broken at the time O:-).
I have CCed Luiz who has been working on moving commands off the old
MONITOR_CMD_ASYNC flag. My current understanding is that patches
adding use of MONITOR_CMD_ASYNC will not be accepted.
> 2) Poll the qemu monitor
> To do it this way, I would write a function that repeatedly calls
> virDomainGetBlockJobInfo() against the disk in question. Once the job
> disappears from the list I can return with confidence that the job is gone.
> This is obviously sub-optimal because I need to poll and sleep.
We've done this before, for both HMP and JSON - see
qemuMigrationWaitForCompletion. I agree that an event is nicer than
polling, but we may be locked into this.
This seems like the safest option although it's ugly.
Stefan