[IMPALA-4547] Fix ExecEnv singleton issues in tests

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Impala 2.8.0
• Fix Version/s: Impala 2.9.0
• Component/s: Backend
• Labels: newbie
• Target Version: Product Backlog
• Assignee: Unassigned
• Reporter: Henry Robinson
• Created: 28/Nov/16 19:53
• Updated: 09/May/17 23:21
• Resolved: 19/Apr/17 22:55

Description

Some test suites create and destroy ExecEnv objects with every test case.

However ExecEnv is meant to be used as a singleton, and the logic right now has the c'tor install the singleton pointer just once:

if (exec_env_ == NULL) exec_env_ = this;

So after TestEnv destroys its ExecEnv, the singleton pointer is invalid; any classes that use ExecEnv::GetInstance() aren't compatible with TestEnv usage.

We should add ExecEnv::InstallNewSingleton() or similar to allow test environments to reset the global singleton.