Re: [libvirt] [PATCH v4 1/8] snapshot: Add new API for bulk dumpxml/redefine

On Mon, Mar 11, 2019 at 09:38:32PM -0500, Eric Blake wrote: > Right now, copying the state of a transient domain with snapshots from > one host to another requires multiple API calls on both machines - on > the host: get the domain XML, get a list of the snapshots, and then > for each snapshot get the snapshot's XML; then on the destination: > create the domain, then multiple domain snapshot create calls (must > be in topological order) with the REDEFINE flag. This patch aims to > make the process use fewer APIs by making it possible to grab the XML > for all snapshots at once on the source, then redefine from that same > list at the destination. In fact, although it is easy to match recent > changes to allow output in topological order, it is also easy to do > bulk redefine in arbitrary order. > > Consideration was given to adding a flag to existing APIs; but to do > that, there would be an asymmetry of dumping <snapshots> as a > sub-element of <domain> during virDomainGetXMLDesc(), vs. redefining > <snapshots> as a top-level element (and different than the normal > top-level element) of virDomainSnapshotCreateXML(). Thus, it is > cleaner to have two new APIs: > > virDomainGetSnapshotsXMLDesc > virDomainImportSnapshotsXML These do not share a common prefix, but that makes them look nicer IMO.

> > Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; > --- > include/libvirt/libvirt-domain-snapshot.h |  16 ++- > src/driver-hypervisor.h                   |  13 ++- > src/libvirt-domain-snapshot.c             | 122 +++++++++++++++++++++- > src/libvirt_public.syms                   |   2 + > 4 files changed, 148 insertions(+), 5 deletions(-) > > diff --git a/include/libvirt/libvirt-domain-snapshot.h > b/include/libvirt/libvirt-domain-snapshot.h > index 602e5def59..7c2e001b87 100644 > --- a/include/libvirt/libvirt-domain-snapshot.h > +++ b/include/libvirt/libvirt-domain-snapshot.h > @@ -3,7 +3,7 @@ >  * Summary: APIs for management of domain snapshots >  * Description: Provides APIs for the management of domain snapshots >  * > - * Copyright (C) 2006-2014 Red Hat, Inc. > + * Copyright (C) 2006-2019 Red Hat, Inc. Do we actually care about updating these?

But an include file will possibly be read by people without git access.

> + * > + * Returns a count of snapshots imported on success, or -1 on failure. This says nothing about partial success, i.e. whether the count returned can be different from the number of snapshots present in the file.

> /** >  * virDomainSnapshotGetXMLDesc: >  * @snapshot: a domain snapshot object > @@ -254,8 +314,8 @@ virDomainSnapshotCreateXML(virDomainPtr domain, >  * VIR_DOMAIN_SNAPSHOT_XML_SECURE; this flag is rejected on read-only >  * connections. >  * > - * Returns a 0 terminated UTF-8 encoded XML instance, or NULL in case > of error. > - *         the caller must free() the returned value. > + * Returns a 0 terminated UTF-8 encoded XML instance, or NULL in case > + * of error.  The caller must free() the returned value. Unrelated change.