[HBASE-15843] Replace RegionState.getRegionInTransition() Map with a Set

• Type: Improvement
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 1.3.0, 1.2.1, 2.0.0
• Fix Version/s: 1.4.0, 2.0.0
• Component/s: master, Region Assignment
• Assignee: Matteo Bertozzi
• Reporter: Matteo Bertozzi
• Created: 17/May/16 02:55
• Updated: 19/May/16 06:06
• Resolved: 18/May/16 20:05

Description

RegionState.getRegionInTransition() is always used as a Set.
replace the Map with a Set, avoid some allocation and extra code.

also ClusterStatus.RegionInTransition has duplicated information.
The spec field contains the regionName (not encoded).
but we have the same info as part of the region_state with the HRegionInfo serialized.
unfortunately I don't think we can get rid of 'spec' that being a required field.

message RegionInTransition {
  required RegionSpecifier spec = 1;
  required RegionState region_state = 2;
}