Corrupted MD-SAL queries when trying to read flows on tables: missing flow rules - openflow

Question

I am experiencing a glitch from OpenDaylight (using Mininet).
Essentially, I am querying flow rules on specific nodes and on specific tables. The relevant code is the following, and is run by 1 separate thread per node that I am polling:
public static final InstanceIdentifier<Nodes NODES_II = InstanceIdentifier
.builder(Nodes.class).build();
public static InstanceIdentifier<Table> makeTableIId(NodeId nodeId, Short tableId) {
return NODES_IID.child(Node.class, new NodeKey(nodeId))
.augmentation(FlowCapableNode.class)
.child(Table.class, new TableKey(tableId));
}
and
InstanceIdentifier<Table> tableIId = makeTableIId(nodeId, tableId);
Optional<Table> tableOptional = dataBroker.newReadOnlyTransaction()
.read(LogicalDatastoreType.OPERATIONAL, tableIId).get();
if(!tableOptional.isPresent()) {
continue;
}
List<Flow> flows = tableOptional.get().getFlow();
The behavior: tableOptional is present, and getFlow() returns an empty list.
The observation: there ARE flow rules installed on ALL nodes on the tables I am querying, but for some reason, some of these nodes show none of these flows on none of the tables (here, tables 3, 4, 5, and 6).
The weirdness: On one of the problematic nodes, I have four rules, installed on tables 9, 13, 17 and 22 respectively. They timeout simultaneously after 150 seconds. After they disappear, the query suddenly begins to "see" the flows installed on tables 3, 4, 5, and 6, returning these for each table.
Question: How is this even possible?
EDIT I just realized that the rules whose timeout "suddenly fix everything" were also rules that generated warnings in ODL's log (OpenFlowPlugin to be more specific). I did not observe any obvious issue, so I'd sort of brushed it aside.
Here is the code relevant to the error:
https://pastebin.com/yJDZesXU
Here are the errors I get every time I install a rule that walks through these lines:
https://pastebin.com/c9HYLBt6
I must stress that these rules work as intended, and that printing them out reveals no evident formatting issue. Again, they appear fine when dumped.
My hypothesis is that this warning is a symptom of ODL "messing up" trying to store the rules in MD-SAL, which ends up messing a lot of rule-reading queries. On uninstallation of the garbage that ensues, rule-reading queries become functional again.
This makes sense to me, but then... I haven't understood how to fix these warnings, or what these warnings were about in the first place.
EDIT 2: By commenting lines suspecting of causing the warnings in the above pastebin:
//ipv4MatchBuilder.setIpv4SourceAddressNoMask(...);
//ipv4MatchBuilder.setIpv4SourcenArbitraryBitmask(...);
The warnings disappear, AND the flows appear correctly on all tables, when pinged. This confirms my hypothesis that somewhere, something wrong happens in the data store.
EDIT 3: I have found that by setting any non-trivial arbitrary bitmask, this error goes away. That is, I have tried setting an arbitrary bitmask which was neither null nor "255.255.255.255", and this error has gone away. The problem is I might like having a bitmask for the source, but an exact match on the destination. Even setting the bitmask to "127.255.255.255" (as I tried) is still unnerving. It really feels to me like this is an OpenFlowPlugin glitch, though.
EDIT 4: Steps for reproducing the bug
Install a rule with ipv4 arbitrary bitmask match, with the destination ip set, and the destination arbitrary bitmask either null or set to 255.255.255.255.
Ipv4MatchArbitraryBitMaskBuilder ipv4MatchBuilder = new Ipv4MatchArbitraryBitMaskBuilder();
ipv4MatchBuilder.setIpv4DestinationAddressNoMask(new Ipv4Address("10.0.0.1"));
ipv4MatchBuilder.setIpv4DestinationArbitraryBitmask(new DottedQuad("255.255.255.255"));
matchBuilder = new MatchBuilder().setEthernetMatch(ethernetMatchBuilder.build()).setLayer3Match(ipv4MatchBuilder.build());
... and so on ...
Extra optional steps: Install one such rule for the destination, one such rule for the source, and install equivalent rules where the bitmask is set to something else, like 127.255.255.255.
Make a query to MDSal to fetch flow information from the node on which you installed the flow rule.
Now, do "log:display" inside your ODL controller. You should have a warning about a malformed destination address. Additionally, the Table object you queried should contain no flows, so tableObject.getFlow() should return an empty list.