[KUDU-640] Collect coverage from external minicluster tests

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Private Beta
• Component/s: build, test
• Target Version/s: Public beta
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 05/Mar/15 20:10
• Updated: 01/May/15 15:58
• Resolved: 01/May/15 15:58

Description

Currently we have a coverage build, but it's a little lacking because the coverage instrumentation only flushes on a successful exit. In all of our external minicluster tests, we kill -9 the daemons, so they don't get a chance to flush their coverage.

The two ways I can think of to fix this are:
1) add an RPC like "FlushCoverage()" which would, if coverage is enabled, call __gcov_flush(). We could have the ext minicluster call this before sending SIGKILL
2) switch to something like AsanCoverage (https://code.google.com/p/address-sanitizer/wiki/AsanCoverage) which has a mode where it keeps running coverage data in an mmaped file