[libvirt] [PATCH v7 07/23] backup: Introduce virDomainBackup APIs

[Daniel P. Berrangé]

On Wed, Mar 27, 2019 at 05:10:38AM -0500, Eric Blake wrote:
> Introduce a few new public APIs related to incremental backups.  This
> builds on the previous notion of a checkpoint (without an existing
> checkpoint, the new API is a full backup, differing from
> virDomainBlockCopy in the point of time chosen and in operation on
> multiple disks at once); and also allows creation of a new checkpoint
> at the same time as starting the backup (after all, an incremental
> backup is only useful if it covers the state since the previous
> backup).  Snapshot creation is also a point in time at which creating
> a checkpoint atomically can be useful; as checkpoints are independent
> objects, it is not worth embedding <domaincheckpoint> inside
> <domainsnapshot>, and therefore we need a more powerful version of
> virDomainSnapshotCreateXML(), where we borrow from the naming pattern
> of virDomainMigrate2() and friends.
> 
> A backup job also affects filtering a listing of domains, as well as
> adding event reporting for signaling when a push model backup
> completes (where the hypervisor creates the backup); note that the
> pull model does not have an event (starting the backup lets a third
> party access the data, and only the third party knows when it is
> finished).
> 
> Since multiple backup jobs can be run in parallel in the future (well,
> qemu doesn't support it yet, but we don't want to preclude the idea),
> virDomainBackupBegin() returns a positive job id, and the id is also
> visible in the backup XML. But until a future libvirt release adds a
> bunch of APIs related to parallel job management where job ids will
> actually matter, the documentation is also clear that job id 0 means
> the 'currently running backup job' (provided one exists), for use in
> virDomainBackupGetXMLDesc() and virDomainBackupEnd().
> 
> The full list of new API:
>         virDomainBackupBegin;
>         virDomainBackupEnd;
>         virDomainBackupGetXMLDesc;
>         virDomainSnapshotCreateXML2;
> 
> Signed-off-by: Eric Blake <eblake at redhat.com>
> ---
>  include/libvirt/libvirt-domain-snapshot.h |   8 +-
>  include/libvirt/libvirt-domain.h          |  41 +++-
>  src/driver-hypervisor.h                   |  21 ++
>  src/qemu/qemu_blockjob.h                  |   1 +
>  examples/object-events/event-test.c       |   3 +
>  src/conf/domain_conf.c                    |   2 +-
>  src/libvirt-domain-snapshot.c             |  89 +++++++++
>  src/libvirt-domain.c                      | 221 +++++++++++++++++++++-
>  src/libvirt_public.syms                   |   4 +
>  tools/virsh-domain.c                      |   8 +-
>  10 files changed, 391 insertions(+), 7 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange at redhat.com>


Regards,
Daniel
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