[CALCITE-5841] Improve the logic of creating JDBCMeta singleton in calcite plus

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.34.0
• Fix Version/s: 1.36.0
• Component/s: extensions
• Labels: pull-request-available
• Assignee: Ran Tao
• Reporter: Ran Tao
• Created: 12/Jul/23 15:58
• Updated: 10/Nov/23 11:34
• Resolved: 29/Jul/23 08:48

Description

current the logic of creating JdbcMeta singleton could be not safe in multi-thread occasion.

we can add double-checking.

    private static JdbcMeta getInstance() {
      if (instance == null) {
        try {
          instance =
              new JdbcMeta(CalciteConnectionProvider.DRIVER_URL,
                  CONNECTION_PROVIDER.provideConnectionInfo());
        } catch (SQLException | IOException e) {
          throw new RuntimeException(e);
        }
      }
      return instance;
    } 

Issue Links

• links to: GitHub Pull Request #3313