[KUDU-2962] Fix kudu::itest::FindTabletFollowers() test utility function

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.12.0
• Component/s: test
• Labels: newbie
• Code Review: https://gerrit.cloudera.org/c/14533/
• Assignee: Bankim Bhavsar
• Reporter: Alexey Serbin
• Created: 01/Oct/19 19:17
• Updated: 24/Oct/19 22:48
• Resolved: 24/Oct/19 22:48

Description

The kudu::itest::FindTabletFollowers() function is unsafe: it uses kudu::itest::FindTabletLeader() to generate the result as a complement to tablet servers hosting the leader replica, but it doesn't sanitize the set of tablet servers to make sure it contains only tablet servers hosting replicas of the specified tablet.

For example, if you have a cluster with 10 tablet servers, and a tablet with 3 tablet replicas, passing the map for all tablet servers in the 10-node cluster would result in FindTabletFollowers() reporting 9 followers. Whoops!

It's necessary to either fix the implementation of this utility function to sanitize its first argument, or simply get rid of it.