A UDPS_TIME_FIRST_SAMPLE time signal carries one meaningful value -- the
batch's first sample -- but a scalar signal in Accumulate mode still occupies
num_samples slots on the wire, which a producer fills by repeating that
anchor. Deriving the step from value_of(n - 1) therefore came out as zero, so
every sample of a frame landed on one x, the degeneracy guard tripped, and the
whole stream was timed by packet arrival instead. On a 1 MS/s source that
arrival clock is not monotonic within a frame: the export's time column held
90559 order breaks.
Space the batch by the cadence, exactly as the LAST_SAMPLE branch beside it
already dates its own batch backwards. The export's time column is now
strictly increasing (0 duplicates, 0 backwards steps) and reads the declared
1 MS/s.
mock_udpstreamer gains --time-mode {full,first}; it could only emit
FULL_ARRAY, so nothing exercised this branch. In 'first' it repeats the anchor
across the batch's wire slots -- the shape that produced the defect -- while
still generating the waveforms from the real per-sample stamps.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The flicker ("no data" at no constant frequency, worse with the measurements
and cursors panes up) was a torn read of the window's first stamp: acquire()
pins the window to the ring's oldest slot, and reading it at paint time races
the producer lapping it, returning a stamp one ring span too new. x0() is the
origin every trace point is reconstructed from, so one torn read produced a
refused neighbours(), a filter that dropped three quarters of the points, and
a polyline shifted off its axis. It is cached by acquire() under the lock now.
EventSeries::neighbours() answered from the (x - x0)/dx grid, whose drift from
the real arrival stamps arrives as a constant offset in seconds -- a doubling
share of the screen per zoom step, which is the "zooming into a held event
clips it more from the left" report. Both series binary-search the stamps now.
The measurements pane went through the LOD pyramid rather than reading its
window raw (19.7 ms per recompute to 1.2 ms, 0.1% of a 2 M-sample window) and
recomputes on a cadence; the math engine lost a per-slot heap allocation, a
per-sample source lookup by name and a fetch_add that cost more than the
arithmetic it counted.
The cursors pane's mix mode drew a line per *named* slot, so a slot holding a
signal that can never produce a channel -- the stream's timestamp -- got a row
that could only read "--", and such names were re-saved every session. It
counts bound traces now and apply_layout() refuses them.
Four toolbar icons are drawn for this app and compiled in as a GResource: the
stock ones were a record dot for the trigger and three magnifiers for cursors,
measurements and math.
New probes and dump lines for all of it (trace ink, measure cost, math cost,
event zoom, toolbar icons); README and CLAUDE.md record what they cure.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
