On Thu, Feb 09, 2023 at 10:23:43AM +0000, Daniel P. Berrangé wrote: > On Wed, Feb 08, 2023 at 02:17:12PM -0600, Eric Blake wrote: > > On Wed, Feb 08, 2023 at 09:35:56AM +0000, Het Gala wrote: > > > Existing 'migrate' QAPI design enforces transport mechanism, ip address > > > of destination interface and corresponding port number in the form > > > of a unified string 'uri' parameter for initiating a migration stream. > > > This scheme has a significant flaw in it - double encoding of existing > > > URIs to extract migration info. > > > > > > The current patch maps QAPI uri design onto well defined MigrateChannel > > > struct. This modified QAPI helps in preventing multi-level uri > > > encodings ('uri' parameter is kept for backward compatibility). > > > > > > Suggested-by: Daniel P. Berrange <berra...@redhat.com> > > > Suggested-by: Manish Mishra <manish.mis...@nutanix.com> > > > Suggested-by: Aravind Retnakaran <aravind.retnaka...@nutanix.com> > > > Signed-off-by: Het Gala <het.g...@nutanix.com> > > > --- > > > qapi/migration.json | 131 +++++++++++++++++++++++++++++++++++++++++++- > > > 1 file changed, 129 insertions(+), 2 deletions(-) > > > > > > diff --git a/qapi/migration.json b/qapi/migration.json > > > index c84fa10e86..79acfcfe4e 100644 > > > --- a/qapi/migration.json > > > +++ b/qapi/migration.json > > > @@ -1449,12 +1449,108 @@ > > > ## > > > { 'command': 'migrate-continue', 'data': {'state': 'MigrationStatus'} } > > > > > > +## > > > +# @MigrateTransport: > > > +# > > > +# The supported communication transport mechanisms for migration > > > +# > > > +# @socket: Supported communication type between two devices for > > > migration. > > > +# Socket is able to cover all of 'tcp', 'unix', 'vsock' and > > > +# 'fd' already > > > +# > > > +# @exec: Supported communication type to redirect migration stream into > > > file. > > > +# > > > +# @rdma: Supported communication type to redirect rdma type migration > > > stream. > > > +# > > > +# Since 8.0 > > > +## > > > +{ 'enum': 'MigrateTransport', > > > + 'data': ['socket', 'exec', 'rdma'] } > > > + > > > +## > > > +# @MigrateSocketAddr: > > > +# > > > +# To support different type of socket. > > > +# > > > +# @socket-type: Different type of socket connections. > > > +# > > > +# Since 8.0 > > > +## > > > +{ 'struct': 'MigrateSocketAddr', > > > + 'data': {'socket-type': 'SocketAddress' } } > > > > Here, you use 'socket-type',... > > > > > + > > > +## > > > +# @MigrateExecAddr: > > > + # > > > + # Since 8.0 > > > + ## > > > +{ 'struct': 'MigrateExecAddr', > > > + 'data' : {'data': ['str'] } } > > > > Inconsistent on whether you have a space before :. Most of our qapi > > files prefer the layout: > > > > 'key': 'value' > > > > that is, no space before, one space after. It doesn't affect > > correctness, but a consistent visual style is worth striving for. > > > > > + > > > +## > > > +# @MigrateRdmaAddr: > > > +# > > > +# Since 8.0 > > > +## > > > +{ 'struct': 'MigrateRdmaAddr', > > > + 'data' : {'data': 'InetSocketAddress' } } > > > > ...while these branches supply everything else under 'data'. Also, > > while you documented @socket-type above, you did not document @data in > > either of these two types. [1] > > > > > + > > > +## > > > +# @MigrateAddress: > > > +# > > > +# The options available for communication transport mechanisms for > > > migration > > > +# > > > +# Since 8.0 > > > +## > > > +{ 'union' : 'MigrateAddress', > > > + 'base' : { 'transport' : 'MigrateTransport'}, > > > + 'discriminator' : 'transport', > > > + 'data' : { > > > + 'socket' : 'MigrateSocketAddr', > > > + 'exec' : 'MigrateExecAddr', > > > + 'rdma': 'MigrateRdmaAddr' } } > > > > Another example of inconsistent spacing around :. > > > > I'm guessing the reason you didn't go with 'socket': 'SocketAddress' > > is that SocketAddress is itself a discriminated union, and Markus does > > not yet have the QAPI generator wired up to support one union as a > > branch of another larger union? It leads to extra nesting on the wire > > [2] > > I don't know the backstory on this limitation. Is it something that > is very difficult to resolve ? I think it is highly desirable to have > 'socket': 'SocketAddress' here. It would be a shame to introduce this > better migration API design and then have it complicated by a possibly > short term limitation of QAPI.
So to understand this better I did this change on top of Het's patch: diff --git a/qapi/migration.json b/qapi/migration.json index 79acfcfe4e..bbc3e66ad6 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -1467,18 +1467,6 @@ { 'enum': 'MigrateTransport', 'data': ['socket', 'exec', 'rdma'] } -## -# @MigrateSocketAddr: -# -# To support different type of socket. -# -# @socket-type: Different type of socket connections. -# -# Since 8.0 -## -{ 'struct': 'MigrateSocketAddr', - 'data': {'socket-type': 'SocketAddress' } } - ## # @MigrateExecAddr: # @@ -1487,14 +1475,6 @@ { 'struct': 'MigrateExecAddr', 'data' : {'data': ['str'] } } -## -# @MigrateRdmaAddr: -# -# Since 8.0 -## -{ 'struct': 'MigrateRdmaAddr', - 'data' : {'data': 'InetSocketAddress' } } - ## # @MigrateAddress: # @@ -1506,9 +1486,9 @@ 'base' : { 'transport' : 'MigrateTransport'}, 'discriminator' : 'transport', 'data' : { - 'socket' : 'MigrateSocketAddr', + 'socket' : 'SocketAddress', 'exec' : 'MigrateExecAddr', - 'rdma': 'MigrateRdmaAddr' } } + 'rdma': 'InetSocketAddress' } } ## # @MigrateChannelType: That results in a build error /home/berrange/src/virt/qemu/scripts/qapi-gen.py: In file included from ../qapi/qapi-schema.json:79: ../qapi/migration.json: In union 'MigrateAddress': ../qapi/migration.json:1505: branch 'socket' cannot use union type 'SocketAddress' To understand what the limitation of QAPI generation is, I blindly disabled this check diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py index cd8661125c..cb5c0385bd 100644 --- a/scripts/qapi/schema.py +++ b/scripts/qapi/schema.py @@ -653,7 +653,7 @@ def check(self, schema, seen): "branch '%s' is not a value of %s" % (v.name, self.tag_member.type.describe())) if (not isinstance(v.type, QAPISchemaObjectType) - or v.type.variants): + or v.type.variants) and False: raise QAPISemError( self.info, "%s cannot use %s" @@ -664,7 +664,8 @@ def check_clash(self, info, seen): for v in self.variants: # Reset seen map for each variant, since qapi names from one # branch do not affect another branch - v.type.check_clash(info, dict(seen)) + #v.type.check_clash(info, dict(seen)) + pass class QAPISchemaMember: After doing that, the QAPI code generated handled the union-inside-union case without any problems that I can see. The generated code looks sane and it compiles correctly. So is this actually just a case of overly strict input validation in the QAPI schema parser ? If so, what's the correct way to adapt the checks to permit this usage. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|