docs: public void clear()
                      throws IOException,
                      EOFException,
                      FileManagerException {
          iterationLock.p();
  
          try {
              synchronized (this) {
                  if (filemgr == null) {
                      throw new HashtableOnDiskException("No Filemanager");
                  }
  
                  int tableid = header.currentTableId();
                  clears++;
  
                  for (int i = 0; i < header.tablesize(); i++) {
                      filemgr.seek(header.calcOffset(i, tableid));
                      long location = filemgr.readLong();
  
                      while (location != 0) { // clear out buckets
                          filemgr.seek(location); // look for "next" pointer
                          long next = filemgr.readLong();
                          header.decrementObjectCount();
                          filemgr.deallocate(location);
                          location = next;
                      }
  
                      writeHashIndex(i, 0, tableid); // broken, jrc
                  }
              }
          } finally {
              iterationLock.v();
          }
      }