@Override
  public List<String> getAllPeersFromHFileRefsQueue() throws ReplicationException {
    List<String> peerIds = new ArrayList<>();
    Scan scan = new Scan().addFamily(HFILE_REF_FAMILY).setReadType(ReadType.STREAM)
      .setFilter(new KeyOnlyFilter());
    try (Table table = conn.getTable(tableName); ResultScanner scanner = table.getScanner(scan)) {
      for (;;) {
        Result result = scanner.next();
        if (result == null) {
          break;
        }
        peerIds.add(Bytes.toString(result.getRow()));
      }
    } catch (IOException e) {
      throw new ReplicationException("failed to getAllPeersFromHFileRefsQueue", e);
    }
    return peerIds;
  }
HBase table based replication queue storage.
hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/TableReplicationQueueStorage.java