[MDSAL-730] Clean up InstanceIdentifier semantics

Sat, 12 Mar 2022 18:24:14 +0000

With ~~MDSAL-696~~, BGPCEP is not quite happy and reports this:

org.opendaylight.mdsal.binding.dom.codec.api.IncorrectNestingException: interface org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.Update is not a valid data tree child of SchemaRootCodecContext [interface org.opendaylight.yangtools.yang.binding.DataRoot]
        at org.opendaylight.mdsal.binding.dom.codec.api.IncorrectNestingException.create(IncorrectNestingException.java:26)
        at org.opendaylight.mdsal.binding.dom.codec.impl.SchemaRootCodecContext.createDataTreeChildContext(SchemaRootCodecContext.java:280)
        at org.opendaylight.mdsal.binding.dom.codec.impl.SchemaRootCodecContext$1.load(SchemaRootCodecContext.java:70)
        at org.opendaylight.mdsal.binding.dom.codec.impl.SchemaRootCodecContext$1.load(SchemaRootCodecContext.java:67)
        at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3533)
        at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2282)
        at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2159)
        at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2049)
        at com.google.common.cache.LocalCache.get(LocalCache.java:3966)
        at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3989)
        at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4950)
        at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4956)
        at org.opendaylight.mdsal.binding.dom.codec.impl.SchemaRootCodecContext.getOrRethrow(SchemaRootCodecContext.java:394)
        at org.opendaylight.mdsal.binding.dom.codec.impl.SchemaRootCodecContext.streamChild(SchemaRootCodecContext.java:231)
        at org.opendaylight.mdsal.binding.dom.codec.impl.DataContainerCodecContext.bindingPathArgumentChild(DataContainerCodecContext.java:113)
        at org.opendaylight.mdsal.binding.dom.codec.impl.SchemaRootCodecContext.bindingPathArgumentChild(SchemaRootCodecContext.java:376)
        at org.opendaylight.mdsal.binding.dom.codec.impl.BindingCodecContext.getCodecContextNode(BindingCodecContext.java:241)
        at org.opendaylight.mdsal.binding.dom.codec.impl.BindingCodecContext.newWriterAndIdentifier(BindingCodecContext.java:203)
        at org.opendaylight.mdsal.binding.dom.codec.impl.BindingCodecContext.toNormalizedNode(BindingCodecContext.java:522)
        at org.opendaylight.mdsal.binding.dom.codec.spi.ForwardingBindingDOMCodecServices.toNormalizedNode(ForwardingBindingDOMCodecServices.java:66)
        at org.opendaylight.protocol.bgp.rib.spi.AbstractRIBSupportTest.createNlriWithDrawnRoute(AbstractRIBSupportTest.java:125)
        at org.opendaylight.protocol.bgp.inet.IPv4RIBSupportTest.testDeleteRoutes(IPv4RIBSupportTest.java:85)

As the error indicates, for some reason we are attempting to access a Notification as a data context – which is definitely not right. We are most likely missing a recognition that we need to access a class through Notification code path.

The core problem is that InstanceIdentifier harks back to initial design where a DataObject was enough to identify an item. This capability was then relaxed to allow reuse of InstanceIdentifier to identify even RpcInput/RpcOutput/Notification and Groupings in the context of mdsal-binding-dom-codec. This is obviously wrong, as noted in ~~MDSAL-724~~.

Tie up the loose ends in InstanceIdentifier definition to require properly-rooted hierarchy, thus rejecting attempts to address invalid items.

There are two different solutions. For simple cases, like

module foo {
  namespace foo;
  prefix foo;

  container foo;
}

the following continues to work

InstanceIdentifier<Foo> id = InstanceIdentifier.create(Foo.class);

For more complex cases involving grouping and choices, such as:

module foo {
  namespace foo;
  prefix foo;

  choice foo {
    container bar;
  }

  grouping grp {
    container baz;
  }

  uses grp;
}

The solution is to go through a specifically-crafted InstanceIdentifierBuilder. The choice/case interface is already covered with pre-existing methods, but for the case of used groupings, the root needs to be specified like this:

InstanceIdentifier<Bar> id = InstanceIdentifier.builderOfInherited(FooData.class, Bar.class).build();

Here FooData identifies the module in which the grouping is instantiated and Bar identifies the container as it would normally do.

OpenDaylight JIRA

[MDSAL-730] Clean up InstanceIdentifier semantics