[KUDU-1715] Add a way to set ReplicaSelection to the java client

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.0
• Fix Version/s: 1.1.0
• Component/s: client
• Target Version/s: 1.1.0
• Code Review: https://gerrit.cloudera.org/#/c/4837/
• Assignee: Jean-Daniel Cryans
• Reporter: David Alves
• Created: 20/Oct/16 20:17
• Updated: 27/Oct/16 18:42
• Resolved: 27/Oct/16 18:42

Description

On the C++ client we're able to set a ReplicaSelection policy on the KuduScanner that hints at which replica should be chosen to perform the scan:

Status SetSelection(KuduClient::ReplicaSelection selection)

... where ReplicaSelection can have the following values:

    LEADER_ONLY,      ///< Select the LEADER replica.

    CLOSEST_REPLICA,  ///< Select the closest replica to the client,
                      ///< or a random one if all replicas are equidistant.
    FIRST_REPLICA     ///< Select the first replica in the list.

Having the same functionality in the java client will increase our confidence in our tests that use and would be helpful for perf, since it's pretty common for leaders to get clustered and the java client only scans from the leader currently.