Eric Blake 0d44788fc3 backup: Introduce virDomainCheckpoint APIs ... Introduce a bunch of new public APIs related to backup checkpoints. Checkpoints are modeled heavily after virDomainSnapshotPtr (both represent a point in time of the guest), although a snapshot exists with the intent of rolling back to that state, while a checkpoint exists to make it possible to create an incremental backup at a later time. We may have a future hypervisor that can completely manage checkpoints without libvirt metadata, but the first two planned hypervisors (qemu and test) both always use libvirt for tracking metadata relations between checkpoints, so for now, I've deferred the counterpart of virDomainSnapshotHasMetadata for a separate API addition at a later date if there is ever a need for it. Note that until we allow snapshots and checkpoints to exist simultaneously on the same domain (although the actual prevention of this will be in a separate patch for the sake of an easier revert down the road), that it is not possible to branch out to create more than one checkpoint child to a given parent, although it may become possible later when we revert to a snapshot that coincides with a checkpoint. This also means that for now, the decision of which checkpoint becomes the parent of a newly created one is the only checkpoint with no child (so while there are APIs for dealing with a current snapshot, we do not need those for checkpoints). We may end up exposing a notion of a current checkpoint later, but it's easier to add stuff when proven needed than to blindly support it now and wish we hadn't exposed it. The following map shows the API relations to snapshots, with new APIs on the right: Operate on a domain object to create/redefine a child: virDomainSnapshotCreateXML virDomainCheckpointCreateXML Operate on a child object for lifetime management: virDomainSnapshotDelete virDomainCheckpointDelete virDomainSnapshotFree virDomainCheckpointFree virDomainSnapshotRef virDomainCheckpointRef Operate on a child object to learn more about it: virDomainSnapshotGetXMLDesc virDomainCheckpointGetXMLDesc virDomainSnapshotGetConnect virDomainCheckpointGetConnect virDomainSnapshotGetDomain virDomainCheckpointGetDomain virDomainSnapshotGetName virDomainCheckpiontGetName virDomainSnapshotGetParent virDomainCheckpiontGetParent virDomainSnapshotHasMetadata (deferred for later) virDomainSnapshotIsCurrent (no counterpart, see note above) Operate on a domain object to list all children: virDomainSnapshotNum (no counterparts, these are the old virDomainSnapshotListNames racy interfaces) virDomainSnapshotListAllSnapshots virDomainListAllCheckpoints Operate on a child object to list descendents: virDomainSnapshotNumChildren (no counterparts, these are the old virDomainSnapshotListChildrenNames racy interfaces) virDomainSnapshotListAllChildren virDomainCheckpointListAllChildren Operate on a domain to locate a particular child: virDomainSnapshotLookupByName virDomainCheckpointLookupByName virDomainSnapshotCurrent (no counterpart, see note above) virDomainHasCurrentSnapshot (no counterpart, old racy interface) Operate on a snapshot to roll back to earlier state: virDomainSnapshotRevert (no counterpart, instead checkpoints are used in incremental backups via XML to virDomainBackupBegin) Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>		2019-07-26 16:48:58 -05:00
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libvirt	backup: Introduce virDomainCheckpoint APIs	2019-07-26 16:48:58 -05:00