drill

eeeb0759 - DRILL-2547: Don't allow Drill to shut down while queries are still executing

DRILL-2547: Don't allow Drill to shut down while queries are still executing This will cause Drillbit.close() to block until all currently executing fragments have completed. WorkManager - added waitForExit() and indicateIfSafeToExit(), which use a latch to wait to shut down if there are active fragments - waitForExit() times out after 5 seconds Drillbit - call WorkManager.waitForExit() in close()