[libvirt-users] using virDomainMigrateSetMaxDowntime

I would like to use the virDomainMigrateSetMaxDowntime but I'm a bit confused about how to use it. If I try to set the downtime before I call domain.migrate(), I get the error "domain is not being migrated". But I cannot call it afterwards because domain.migrate() does not return until the migration has completed. Am I meant to put the call to domain.migrate() into a separate thread of control, and then call SetMaxDowntime from my main thread after the migration has begun? How do I even know if the migration has begun? Thanks! --Igor