I done that things: -- Add to TcpDiscoverySpi field Comparator<TcpDiscoveryNode> nodeComparator for load custom comparators from config file like bean. -- Add implementation with old behavior: BaseNodeComparator -- Add region id implementation: RegionNodeComparator which get map from IP address to region ID in constructor. -- Modified TcpDiscoveryNodesRing#nextNode for using nodeComparator for find next node.
You can see that in PR: https://github.com/apache/ignite/pull/1436 Main question is: how to test it? For my local test i just changed BaseNodeComparator with this odd comparator: new Comparator<TcpDiscoveryNode>() { @Override public int compare(TcpDiscoveryNode t1, TcpDiscoveryNode t2) { //shuffle nodes final int ans = Long.compare((t1.internalOrder()*3L+13L)%4L, (t2.internalOrder()*3L+13L)%4L); return (ans==0)?t1.compareTo(t2):ans; } }; It's looking scary, but in fact it just consistently shuffle nodes. If you have 4 nodes with topology versions 1, 2, 3 and 4, it will be ring: 1-4-3-2. So I think if we just using in old test this shuffle comparator and nothing gone wrong it's good enough. But any way I don't know how to add that to tests. And may be we need some test for custom comparators. But in fact comparators just must be valid Java comparator and work the same on all nodes. Any comments are welcome.
