Re: [Qemu-devel] [PATCH 6/6] qapi: Convert migrate

[Juan Quintela <quintela@redhat.com>]

Luiz Capitulino <lcapitulino@redhat.com> wrote:
> The migrate command is one of those commands where HMP and QMP completely
> mix up together. This made the conversion to the QAPI (which separates the
> command into QMP and HMP parts) a bit difficult.
>
> The first important change to be noticed is that this commit completes the
> removal of the Monitor object from migration code, started by the previous
> commit.
>
> Another important and tricky change is about supporting the non-detached
> mode. That's, if the user doesn't pass '-d' the migrate command will lock
> the monitor and will only release it when migration is finished.
>
> To support that in the new HMP command (hmp_migrate()), it was necessary
> to create a timer which runs every second and checks if the migration is
> still active. If it's, the timer callback will re-schedule itself to run
> one second in the future. If the migration has already finished, the
> monitor lock is relased and the user can use it normally.
>
> All these changes should be transparent to the user.

> +static void hmp_migrate_status_cb(void *opaque)
> +{
> +    MigrationStatus *status = opaque;
> +    MigrationInfo *info;
> +
> +    info = qmp_query_migrate(NULL);
> +    if (!info->has_status || strcmp(info->status, "active") == 0) {
> +        qemu_mod_timer(status->timer, qemu_get_clock_ms(rt_clock) +
> 1000);

1 second is one eternity.  I will ask for something smaller (100ms or
200ms range).

> +    qmp_migrate(uri, !!blk, blk, !!inc, inc, false, false, &err);

This is the only user of qmp_migrate, why do we need to pass both
has_blk & blk (and inc and !!inc?)  Both parameters are bool, I am
really confused here.

Later, Juan.