new: usr: #162: Added Hadoop2ClusterManagerV2 implememtation of hadoop cluster manager for correct consistent hashing logic

[coveralls]

Pull Request Test Coverage Report for Build 160

• 72 of 122 (59.02%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.0%) to 24.106%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rubix-core/src/main/java/com/qubole/rubix/core/utils/DummyClusterManager.java	0	2	0.0%
rubix-hadoop2/src/main/java/com/qubole/rubix/hadoop2/Hadoop2ClusterManager.java	4	6	66.67%
rubix-presto/src/main/java/com/qubole/rubix/presto/PrestoClusterManager.java	0	2	0.0%
rubix-spi/src/main/java/com/qubole/rubix/spi/ClusterManager.java	0	6	0.0%
rubix-hadoop2/src/main/java/com/qubole/rubix/hadoop2/Hadoop2ClusterManagerUtil.java	30	49	61.22%
rubix-hadoop2/src/main/java/com/qubole/rubix/hadoop2/Hadoop2ClusterManagerV2.java	38	57	66.67%
<!--	Total:	72	122	59.02%	-->

Totals
Change from base Build 155:	1.0%
Covered Lines:	573
Relevant Lines:	2377

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💛 - Coveralls

[vrajat]

One big question is composition vs inheritance between the two implementations of Hadoop Cluster Managers. I probably prefer inheritance in this specific case because tests that are valid for V1 is also valid for V2 except for a few scenarios where you want different scenarios. If you choose composition, then you have to repeat all the tests.

[abhishekdas99]

@vrajat Yes I thought about it. First the tests are same in terms of checking the condition. The output of the tests are going to be different. For example, for testUnhealthyNodeCluster_decommissioned, the old HadoopClusterManager will return 1 node whereas the new implementation is going to return 2 nodes. Both the clustermanagers are extending the abstract class and quite a few implementations are different for these two cases such as initialize, getNextRunningNodeIndex and getPreviousRunningNodeIndex. The common methods which can be used as utility methods have been extracted out to a different Utility class. Same logic has been applied to TestClasses as well.