anchor.diff:                        ?DEFINE_ADDER(queue_drain),
                         ?DEFINE_ADDER(queue_backoff),
                         ?DEFINE_ADDER(queue_backfillremaining),
  -                      ?DEFINE_ADDER(queue_itemondisk)}.
  +                      ?DEFINE_ADDER(queue_itemondisk),
  +                      ?DEFINE_ADDER(total_backlog_size)}.
   -undef(DEFINE_ADDER).
   
   -define(DEFINE_SUBTRACTOR(N), N = A#tap_stream_stats.N - B#tap_stream_stats.N).
  
positive.code:                            queue_drain = 0,
                             queue_backoff = 0,
                             queue_backfillremaining = 0,
                             queue_itemondisk = 0}).
  
  -define(TAP_STAT_GAUGES,
          ep_tap_rebalance_count, ep_tap_rebalance_qlen, ep_tap_rebalance_queue_backfillremaining, ep_tap_rebalance_queue_itemondisk,
          ep_tap_replica_count, ep_tap_replica_qlen, ep_tap_replica_queue_backfillremaining, ep_tap_replica_queue_itemondisk,
          ep_tap_user_count, ep_tap_user_qlen, ep_tap_user_queue_backfillremaining, ep_tap_user_queue_itemondisk,
          ep_tap_total_count, ep_tap_total_qlen, ep_tap_total_queue_backfillremaining, ep_tap_total_queue_itemondisk).
  -define(TAP_STAT_COUNTERS,
          ep_tap_rebalance_queue_fill, ep_tap_rebalance_queue_drain, ep_tap_rebalance_queue_backoff,
          ep_tap_replica_queue_fill, ep_tap_replica_queue_drain, ep_tap_replica_queue_backoff,
  
negative.code: ?DEFINE_EXTRACT(backoff, queue_backoff);
  ?DEFINE_EXTRACT(backfill_remaining, queue_backfillremaining);
  ?DEFINE_EXTRACT(itemondisk, queue_itemondisk);
  ?DEFINE_EXTRACT(total_backlog_size, total_backlog_size);
  ?DEFINE_EXTRACT(count, count);
  extract_agg_stat(_K, _V, Acc) -> Acc.
  -undef(DEFINE_EXTRACT).
  