private void basicClose(LocalRegion region, DiskRegion dr, boolean closeDataOnly) {
    if (dr.isBackup()) {
      if (region != null) {
        region.closeEntries();
      }
      if (!closeDataOnly) {
        getDiskInitFile().closeRegion(dr);
      }
      // call close(dr) on each oplog
      PersistentOplogSet oplogSet = getPersistentOplogSet(dr);
      oplogSet.basicClose(dr);
    } else {
      if (region != null) {
        // OVERFLOW ONLY
        clearAsyncQueue(region, true, null); // no need to try to write these to
                                             // disk any longer
        dr.freeAllEntriesOnDisk(region);
        region.closeEntries();
        overflowMap.remove(dr);
      }
    }
  }
It invokes appropriate methods of super & current class to clear the Oplogs.

@param rvv if not null, clear the region using the version vector
geode-core/src/main/java/org/apache/geode/internal/cache/DiskStoreImpl.java