@Override
  public void init(WALFactory factory, Configuration conf, String providerId, Abortable abortable)
    throws IOException {
    if (null != disabled) {
      throw new IllegalStateException("WALProvider.init should only be called once.");
    }
    if (null == providerId) {
      providerId = "defaultDisabled";
    }
    disabled = new DisabledWAL(new Path(CommonFSUtils.getWALRootDir(conf), providerId), conf, null);
  }
No-op implementation of {@link WALProvider} used when the WAL is disabled. Should only be used
when severe data loss is acceptable.
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/DisabledWALProvider.java