Two changes in the trigger pane, landed together.
**Persistence.** Trigger mode keeps the last N published acquisitions and draws them fading toward
the background, N being a panel control (1..8, default 1) with N=1 meaning today's behaviour
exactly, so the knob is the switch. The layers are the accumulate path's own -- one layer per
(signal, age) in the row's free trace slots, named with the accumulate vocabulary so
`layer_base_name()` strips the suffix and `signal_color()` resolves the base signal -- so a layer is
not a signal: the signal list, the colours and the measurements see one row per signal.
`ScopeModel` retains the outgoing snapshot in seven atomic `shared_ptr` slots (no lock, no copy; the
snapshot already exists) and a layer's channel is resolved **by name inside the snapshot**, because
the channel list is renumbered by any structural change since that acquisition was cut.
`RowSet::sync_layers()` re-plans from the rows and the depth alone, so a latch costs no rebuild, and
`event_data_window()` skips layer slots so an older acquisition can never re-pin the axis. The
schedule is 0.5^age -- the acquisition on screen at full brightness and each older one half the
previous, independent of N, so raising the depth adds dimmer acquisitions rather than rescaling the
ones already on screen. Memory is bounded by the ring's own `--buffer-mb` rather than by the depth,
which is the bound that cannot be driven into an OOM, and the panel says when either bound bites.
This also wired up `set_trace_alpha()`, which the accumulate path was setting and nothing was
reading -- so the documented 0.35 translucency of an accumulation was opaque in fact.
**Force.** In the trigger pane beside Arm/Disarm, shown only while trigger mode is on: one
acquisition now, with the configured window. It is a synthetic edge rather than a second publisher
-- the engine opens one capture at the present moment and everything else is the ordinary latch, so
a forced acquisition is cut, pinned, framed, recorded and cached exactly like a latched one, and
the button owns no window and no publish. The pre-trigger gate is deliberately skipped (capture now
is a request for the history that exists, and the snapshot reports its own shorter pre_s), a
capture already filling is refused rather than restarted, and the state afterwards is the mode's:
Normal stays armed, Single disarms. The request is one atomic flag written under the model mutex
with `armed` -- the producer reads `armed` at the top of a packet and the request at the bottom, so
a request written between the two would be dropped -- and consumed at the end of a packet, after
the channel loop and before the pending publish.
**A defect fixed in passing, in the function Force was modelled on:** `on_arm_clicked()` passed
`TriggerConfig::channel` (an index into `channels()`) to `set_signal_enabled()` (an index into
`signals()`). With one signal acquired, arming switched on the stream's clock signal and left the
watched signal untouched -- and since a signal the panel was not showing is a change, it rebuilt
the buffer under the click, dropping the very pre-trigger window the arming, and now the Force, was
about to capture. Measured before: `0.0100 s of history behind it`; after: `2.5299 s`.
`trigger_signal_index()` is now the one resolution, used by both buttons.
**The clock.** Trigger mode showed a blank plot and never latched when the session defined a math
channel, because such a session gives the model a plan *before* the stream's own signals are in it:
one derived channel, declared rate 0, so `plan_partition()`'s 1 kHz fallback is the interval those
early frames are stamped at -- 1300x too fast for a 1.3 MS/s stream -- and they have nowhere to go,
since the value loop skips derived channels. Relative mode then stamped a *position* times the plan's
*current* interval, so when the CONFIG's channels landed and the plan took the real rate (769 ns) the
same positions produced times 1300x *smaller* than what was already in the ring, and the monotonic
clamp held the clock at the old value for the rest of the run: one repeated stamp, `history=0`, no
latch, and a window the renderer cannot draw. The same family as the restarted-client poisoning
fixed in 620473a, through a different door. The filter's own output was finite and correct
throughout, and disabling the math channel only appeared to cure it because that is a structural
change which rebuilds the store -- the third time that channel has looked guilty while being a
bystander.
Relative mode now accumulates *seconds* (`rel_base_s_ += n * dt`), so a re-plan is a slope change and
the clock cannot jump backwards by construction; a frame is only stamped into a model that has a
*streamed* channel; and the epoch is adopted once per connection, with "unset" a state rather than
the value zero. A one-shot warning names the family if it returns: `the clock stalled at ...: N
samples stamped [a..b] are all behind it`.
**The dialog.** The Configurations window's Close button and the window-manager close both did
nothing: `close-request` was connected to a bare `void` lambda, and that signal is `gboolean` -- TRUE
means "handled" and suppresses the default handler that destroys the window, while `G_CALLBACK` is a
cast, so GTK read whatever the compiler left in the return register. A standalone GTK program of that
shape reproduces it: `void` handler -> `window_alive=1` after `gtk_window_close()`, `gboolean FALSE`
-> 0. The same audit found `gtk_window_present(GTK_WINDOW(...))` on an `AdwDialog`, a type assertion
and a no-op; it is `adw_dialog_present()` now. The menu row stays: it is the only way to switch or
save a configuration without restarting, and what made it look useless was that it could not close.
Verified: trigger mode with that session's graph reads `ring=[0.0058..0.2446] -> [0.0058..1.9969]`,
`history 0.237 -> 2.0 s`, `edge at 1.120 s, latched at 2.120 s`, `display=event(frozen) latches=1`,
`traceless paints 266` against 1519 before the fix. Baselines hold: 0 errors, the documented three
warnings, test-ui 13 ok, test-help green, `gtk warnings: 0`.
The user's real host reported "connected and live" with one missing-data band over the whole window
and no trace in it. The counter is the only thing that claims a packet existed, and a reservation
was booked on its word alone: a source whose DATA counter counts samples, or frames of an inner
layer, advances by more than 1 per datagram, the client cannot check that claim (it has no clock of
its own to compare against), so it holds each packet, saturates its reorder ring, delivers it in
order and reports the skipped counters as lost. Every frame therefore reported a phantom gap, and
`reserve_hole()` wrote `lost * batch_` NaN samples with no bound but the 256-PACKET cap -- the
sample form of that rule ("the number to weigh against the ring is 256 * batch_, not the 256") was
never implemented. With relative time on -- which that session carries -- each phantom gap is
materialised as NaN slots by construction: the window filled with reservations, there was never
anything missing to repair them, and the gaps also stretched the relative clock, which is why the
status bar read live at ten times the true rate.
`Acquisition::gap_plausible()` now gates every reservation on two independent tests: the arrival
clock must corroborate the claim (that many missing packets would take that many frame intervals;
deliberately permissive, because a false refusal costs a shading and never data), and the ring must
be able to hold the hole. The verdict is taken before the stamps, and relative mode's slot advance
is skipped with it, since the advance and the reservation are the same claim. Refusals are counted
in `StreamStats::gaps_refused` and said once per connection with the numbers, naming the wire shape
they describe.
tools/mock_udpstreamer.py gains `--counter-step N`: a counter that is not a packet counter on an
intact link, which is the one shape the mock could not produce and the shape the report came from.
Verified in both directions. A counter stepping 1000 per datagram reads `holes=0 hole_slots=0
backfilled=0` with the traces present (3 traces, 1.4 M samples) against 7.9 M claimed gaps, and the
warning above names the cause. Every other packet withheld -- a real loss -- still reads
`holes=3579`, so genuine gaps are still reserved: a fix that stopped believing real losses would
have traded one wrong picture for another. The user's control read as "the math channel is the
problem" and was confounded -- disabling it is a structural change, which rebuilds the buffer and
clears the accumulated NaN.
Going live from a file view left the display frozen for seconds: the per-second line showed
`ring=[2.5200..2.5200] n=567000 -> n=1131000 -> n=1689000` — the sample count climbing at the stream's rate
while the retained span was one value, the file view's last stamp. The status bar was green because
everything about the *connection* was fine.
It is the poisoning `invariants-data-path.md` already describes, entered through a different door. The
new client's stream clock sits *behind* the stamps the old stream left in `Acquisition::last_stamp_` (the
file view's samples are still in the store), so the advance test rejects every packet of a perfectly good
stream, four rejections abandon the declared time signal, and the arrival-clock fallback derives its epoch
from the surviving mark — every sample stamped flat at the old value. The guard did exactly what it was
built to do; the *stream* was the thing that had changed and nothing had told it.
So `Acquisition::start()` — which is the one place a client (re)starts — now says so:
`ScopeModel::reset_stream()` drops the previous stream's history (`store_->reset()`, which the data-path
invariants require to leave nothing behind) and moves `plan_generation_`, which is what the producer
already watches to drop the state tied to the old store; and `last_stamp_` is re-based to `-infinity` so
the monotonic guard re-bases on the new clock instead of pinning it. The declaration is kept: the first
packet of the new stream passes, and monotonicity holds from there.
One self-inflicted crash on the way, fixed before this: `reset_stream()` dereferenced `store_`, which is
**null until the first CONFIG has planned anything** — at start-up there is none — so the app died with
SIGSEGV and no output at all. Caught by running it plainly rather than trusting the change.
Verified with the events probe (a replay and a group, then *Live*):
live restored (after replay): … pending=0
trig engine: … history=0.4377/0.4000 s now_t=0.298 ring=[-0.1392..0.2985] n=569000
trig engine: … history=0.8723/0.4000 s now_t=0.733 ring=[-0.1392..0.7331] n=1134000 (pending=1: it latched)
trig engine: … history=1.2954/0.4000 s now_t=1.156 ring=[-0.1392..1.1562] n=1684000
`ring` moves within a round-trip, `history` fills, and the trigger latches the frame after the restore;
`make test-ui` 14 files, zero `Gtk-CRITICAL`, and the plain run is clean. Docs: the restart's own door into
the poisoning in `invariants-data-path.md`, and the `ring=` reading's entry in `probe-readings.md` now says
what it must do after *Go live*.
Diagnosing "going live from an event view does nothing for ~5 s, with the status bar green" needed a
distinction the engine's own fields cannot make. `n` counts every stored sample, so it climbs whenever data
arrives at all; what says *why* nothing moves is the store's stamp pair beside it. So the line gains
`ring=[oldest..newest] n=`:
trig engine: … history=0.0000/0.4000 s … now_t=2.520 holdoff_until=2.520 ring=[2.5200..2.5200] n=567000
trig engine: … ring=[2.5200..2.5200] n=1131000
trig engine: … ring=[2.5200..2.5200] n=1689000
Three seconds apart, after `<live>`: the sample count climbs at the stream's rate (the data *is* arriving and
being stored) while the retained span is a single value — the file view's last stamp. So the producer's clock
is **frozen** after the restart, not lagging, which is why `history` never fills, why an armed trigger never
latches, and why a live view with the trigger off does not advance either: one cause, two faces, and it is
not the trigger.
The reading is what tells that apart from a stalled *feed* (ring moving, `now_t` still), which is a different
bug with a different fix — and neither is visible from `now_t` alone. `n` climbing beside a still `ring` is
the clock; a moving `ring` beside a still `now_t` is the feed.
The fix itself is the next piece of work: the producer's clock has to advance across a client restart (or the
file view's retained history has to go when going live), and this pair is the assertion it must satisfy —
after `<live>`, `ring` must move within a stream round-trip. Verified: `make test-ui` 14 files; the fields
observed in the transition run above; no `Gtk-CRITICAL`.
`plan_partition()` only ever chooses powers of two for `time_stride`, and the
comment there already claimed the test was cheap -- but the stride is a runtime
value, so `tick % period` compiled to a real division that the hot loop paid
once per channel per wire sample. The per-channel masks are built where the
partition is already reacted to, and the shared clock's group end is computed
once per sample instead of three times.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The lookup compared raw uint32 counters with >= and <, so a hole spanning the
2^32 wrap matched nothing and every late packet belonging to it was dropped. A
signed delta, the idiom deps/udpsclient already uses throughout.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Four latches were process-lifetime -- two of them function-local statics, so
process-wide rather than per-object -- and a condition that warned once stayed
silent about every later occurrence in a long-lived session. A diagnostic that
goes quiet after the first occurrence is the failure mode worth fixing in a
feature whose job is diagnosis.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
rebuild_locked() replaced the store, so produced() restarted at 0 while the
producer's tick_ kept counting: a hole's slot and tick addressing then described
a buffer that was gone, forget_holes_before() could not retire it, and a
backfill's amend fell outside the ring -- repairing nothing while the hole was
still marked repaired, which is the band reporting the opposite of the truth. A
re-plan generation is the signal rather than the stride/channel-count guard,
which a reconnect with an identical CONFIG leaves unchanged. slot_base_ is left
alone: it is relative mode's clock origin and must not walk backwards when the
user retypes the window.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
A packet that needed a slot and found none was neither held nor delivered: no
counter recorded it and the consumer reserved a hole nothing could ever backfill.
It now commits the gap to free a slot and takes the ordering decision once more
against the sequence that commit left behind, bounded to one retry; past that it
is delivered in order with the counters it skipped as its `lost`, never flagged
late, because a packet ahead of the sequence has no hole to be looked up by. A
duplicate can now replace its slot at a full ring, as hold_packet's own comment
already promised, and the 20 ms default window is a named constant.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Two defects behind one report ("a trigger during a capture overrides the first,
and the hold-off does not apply"); the second is also what made a spike in one
channel look like the acquisition resetting.
The trigger engine keyed its invalidation on the trigger channel's *index*, which
every rebuild of the channel list renumbers -- enabling a signal that sorts before
it is enough. Any rebuild therefore abandoned an open capture and set no hold-off,
so the next edge inside the post window became t0. It keys on the channel's name
now, which changes only when the source genuinely does.
A packet whose stamps jump more than 256 packet spans ahead is now rejected as a
fault and *bridged* at the declared cadence, instead of poisoning the monotonic
mark (which pinned every later packet flat at the glitched value) and condemning
the next good packet. Only four consecutive failures abandon the declared time
signal, and that fallback no longer wipes the rings: the arrival clock is anchored
to continue from the monotonic mark, so the history is still on one timeline --
the wipe is what made one glitching packet look like the stream restarting from 0.
The declared unit is resolved before those checks, since they weigh the stamps
against a cadence in seconds.
Guards: UDPSCOPE_PROBE_TRIGRENUM_MS prints t0_held=1 through the real widgets,
and the mock's --time-glitch-at/--time-glitch-by injects the clock fault.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The time ring was f32 like the values, holding each stamp relative to an epoch
fixed at the first sample ever seen -- so the number stored grew for as long as
the app ran while the interval it had to resolve stayed one sample period. At
1 MS/s the f32 ULP reaches the sample period after about sixteen seconds, so two
to four consecutive samples rounded onto one stamp after half a minute and eight
after a minute. On screen that is a plateau the LOD envelope draws as a
zero-width segment -- a vertical spike where the waveform should be -- and in an
export it was three distinct diffs at 2, 2.5 and 3 ULP instead of one clock.
A value's precision is a property of the signal; a timestamp's is a property of
how long the scope has been running. Only the clock widens: the values are the
memory budget. That makes the two slices different sizes per slot, so
plan_partition() weighs its growth loop in bytes rather than in slots (and
bytes_for() is what bounds the doubling); live_window_locked() loses the f32
round-trip of its bounds, which existed only to keep a sample sitting exactly on
one; and EventSnapshot::stamps is f64 because a pause view is not rebased and so
carries full stream time.
Verified against the fast mock: np.diff over two million exported rows now holds
exactly one step (1e-06, 1999999 times), no duplicate or backwards stamps, and
the 200 MB ring still spans 8.39 s. Every documented probe assertion unchanged.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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>
Martino Ferrari