- Adding javadoc comments
- Bug: ServerStateNode#regions is HashSet but there's no synchronization to prevent concurrent addRegion/removeRegion. Let's use concurrent set instead.
- Use getRegionsInTransitionCount() directly to avoid instead of getRegionsInTransition().size() because the latter copies everything into a new array - what a waste for just the size.
- There's mixed use of getRegionNode and getRegionStateNode for same return type - RegionStateNode. Changing everything to getRegionStateNode. Similarly rename other *RegionNode() fns to *RegionStateNode().
- RegionStateNode#transitionState() return value is useless since it always returns it's first param.
- Other minor improvements
- Moved DrainingServerTracker and RegionServerTracker to hbase-server:o.a.h.h.master.
- Moved SplitOrMergeTracker to oahh.master (because it depends on a PB)
- Moving hbase-client:oahh.zookeeper.* to hbase-zookeeper module. After HBASE-19200, hbase-client doesn't need them anymore (except 3 classes).
- Renamed some classes to use a consistent naming for classes - ZK instead of mix of ZK, Zk , ZooKeeper. Couldn't rename following public classes: MiniZooKeeperCluster, ZooKeeperConnectionException. Left RecoverableZooKeeper for lack of better name. (suggestions?)
- Sadly, can't move tests out because they depend on HBaseTestingUtility (which defeats part of the purpose - trimming down hbase-server tests. We need to promote more use of mocks in our tests)