@Override
      public void afterHavingCompacted() {
        if (!afterWritingBytes) {
          fail("Roller didnt wait for Async writer to terminate!");
          failureCause = "Roller didnt wait for Async writer to terminate!";
          testFailed = true;
        }
      }
DiskRegOplogRollerWaitingForAsyncWriterJUnitTest: Disk Region test : Oplog Roller should wait
for asynch writer to terminate if asynch flush is going on , before deleting the oplog
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/DiskRegOplogSwtchingAndRollerJUnitTest.java