A tie cluster's truncated read left the width at one tick; once the gap
above it was under two milliseconds nothing floored it, so segHi
stepped down one tick per read: 30 rows at one ms 0.3 s below hi with a
carried 1 s width took 10,006 identical reads (S8). (a) The top-anchored
width is floored at the granularity, Min kept; (b) a segment no wider
than the granularity is the unit that escalates to
MaxTieClusterOverfetch and then refuses - per millisecond, exact for the
ms-resolution Gateway (documented). Both are needed: the floor alone
loops on crowded reads with a small tie budget. S8 is a repo test
(4 shapes, reads <= 30, 0 repeated requests); random-data tests now
measure the refusal unit as rows in any 1 ms window. Reviewer harness,
5,000 seeds x default/MSONLY/CROWD: worst page 70 reads (default/MSONLY),
63 (CROWD) at M=65536, p99.9 27-37; no page over 500 reads at any tie
budget.
The null source has no history in either direction; reporting false
made the server walk an empty reverse events read back through three
empty forward reads. It now answers the reverse overload with the empty
result itself (guard test unchanged: it still declares both members).
GatewayHistorianDataSource.ReadEventsAsync sized its result list to
maxEvents, which is int.MaxValue for NumValuesPerNode = 0: every
uncapped Gateway events read (forward on master, and the new walked
reverse one) threw 'Array dimensions exceeded' and counted as a backend
failure. Capacity is bounded at 1024. The events walk delegate moved to
ReverseEventsReader so it is tested over the real Gateway source
(forward uncapped, reverse uncapped, reverse capped).
Joseph Doherty