Commit 0dc70d63 authored by Vacaliuc, Bogdan's avatar Vacaliuc, Bogdan
Browse files

slides: add slide 5 — a peak drag traced from click to plot 



Four-lane swim-lane sequence diagram showing what happens when a
user drags a peak line on the detector plot: 9 numbered steps
flowing UI → Configuration/DataManager → Reduction back-end →
Mantid → back.

Lane colours match the rest of the deck (warm-orange for Qt UI,
amber for Configuration, blue for back-end, green for Mantid).

Mid-slide cost banner names the expensive parts: 2–4 deepcopies
per drag, one full MRR.PyExec per cross-section, all synchronous
on the Qt thread, 1–10 s of frozen UI.

Bottom banner enumerates the five debts scientists perceive as
"Qt leaking into the reduction": synchronous reduction, deepcopy
chain, class-attribute globals, signal-timing fragility, widget
lifecycle. Documents that there are zero Qt imports in the back-end
but the lifecycle fabric drives everything.

Supports Day-1 "why does the UI freeze?" and Day-2 "what does the
reduction actually do?" discussions.

Co-Authored-By: default avatarClaude Opus 4.7 (1M context) <noreply@anthropic.com>
parent 00a81b9e

plan/quicknxsv2-modularization/slides/slide-5-peak-drag-sequence.png

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plan/quicknxsv2-modularization/slides/slide-5-peak-drag-sequence.svg

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  <text x="960" y="55" font-size="34" font-weight="700" fill="white" text-anchor="middle">A Peak Drag, Traced from Click to Plot</text>

  <text x="960" y="85" font-size="17" fill="#B8D4E8" text-anchor="middle">What happens in the 1–10 seconds between moving a peak line and seeing the new reflectivity</text>



  <!-- ─── Swim lanes ─── -->

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  <text x="1080" y="162" font-size="18" font-weight="700" fill="#002E5D" text-anchor="middle">Reduction back-end (runs on Qt thread!)</text>



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  <text x="1615" y="162" font-size="18" font-weight="700" fill="#1F5B1F" text-anchor="middle">Mantid (the reduction engine)</text>



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    <text x="90" y="232" font-size="20" font-weight="700" fill="white" text-anchor="middle">1</text>

    <text x="125" y="218" font-size="15" font-weight="700" fill="#002E5D">User drags peak line</text>

    <text x="125" y="238" font-size="13" fill="#3E2C00">on the detector plot.</text>

    <text x="125" y="255" font-size="12" fill="#606060" font-style="italic">mplwidget mouse event</text>

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  <!-- Step 2: Qt signal -->

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    <text x="90" y="347" font-size="20" font-weight="700" fill="white" text-anchor="middle">2</text>

    <text x="125" y="333" font-size="15" font-weight="700" fill="#002E5D">Qt signal fires</text>

    <text x="125" y="352" font-size="12" fill="#606060" font-family="monospace">motion_notify_event</text>

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  <!-- Step 3: update_configuration_from_ui -->

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    <text x="360" y="402" font-size="20" font-weight="700" fill="white" text-anchor="middle">3</text>

    <text x="395" y="388" font-size="15" font-weight="700" fill="#3A2C00">update_configuration_from_ui()</text>

    <text x="395" y="406" font-size="12" fill="#3A2C00">Read every widget → write Configuration instance</text>

    <text x="395" y="422" font-size="12" fill="#3A2C00" font-style="italic">~40 widget.value() / isChecked() / currentIndex() calls</text>

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  <!-- Step 4: DataManager.update_configuration -->

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    <text x="360" y="517" font-size="20" font-weight="700" fill="white" text-anchor="middle">4</text>

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    <text x="395" y="515" font-size="12" fill="#3A2C00">Routes Configuration to every loaded NexusData.</text>

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  <!-- Step 5: deepcopy -->

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    <text x="360" y="632" font-size="20" font-weight="700" fill="white" text-anchor="middle">5</text>

    <text x="395" y="611" font-size="15" font-weight="700" fill="#3A2C00">deepcopy × N cross-sections</text>

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    <text x="395" y="647" font-size="11" fill="#C8102E" font-style="italic">2–4 deepcopies per peak drag · ~1–5 ms each</text>

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  <!-- Step 6: calculate_reflectivity -->

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    <text x="850" y="727" font-size="20" font-weight="700" fill="white" text-anchor="middle">6</text>

    <text x="885" y="706" font-size="15" font-weight="700" fill="#002E5D">NexusData.calculate_reflectivity(…)</text>

    <text x="885" y="724" font-size="12" fill="#1F3A5F">Groups workspaces; builds ~35 MRR kwargs;</text>

    <text x="885" y="741" font-size="12" fill="#1F3A5F">applies <tspan font-family="monospace">_as_ints</tspan> (one of two local variants).</text>

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  <!-- Step 7: MRR.PyExec -->

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    <text x="1415" y="744" font-size="15" font-weight="700" fill="#002E5D">MagnetismReflectometryReduction.PyExec</text>

    <text x="1415" y="762" font-size="12" fill="#1F3A1F">859 LOC Python, per cross-section executes:</text>

    <text x="1415" y="780" font-size="11.5" fill="#1F5B1F" font-family="monospace">Rebin · RefRoi (×2) · Minus · NormaliseByCurrent ·</text>

    <text x="1415" y="796" font-size="11.5" fill="#1F5B1F" font-family="monospace">Divide · ConvertToPointData · Rebin · cleanup</text>

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  <!-- Step 8: CrossSection caches -->

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    <text x="850" y="827" font-size="20" font-weight="700" fill="white" text-anchor="middle">8</text>

    <text x="885" y="805" font-size="15" font-weight="700" fill="#002E5D">CrossSectionData caches Q, R, dR</text>

    <text x="885" y="823" font-size="12" fill="#1F3A5F">Applies QuickNXS compat scale factor</text>

    <text x="885" y="841" font-size="11.5" fill="#8C3A00" font-style="italic">— with +1.0 on this path, without on the CSD path (~1% drift)</text>

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  <!-- Step 9: plot redraws -->

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    <text x="125" y="460" font-size="12" fill="#3E2C00" font-style="italic">matplotlib canvas update</text>

    <text x="125" y="477" font-size="11" fill="#606060">(UI thread finally unblocked)</text>

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    <text x="20" y="28" font-size="14.5" fill="#F5C13A" font-weight="700">Cost of one peak-drag:</text>

    <text x="220" y="28" font-size="13" fill="#E0ECF5">2–4 × <tspan font-family="monospace" fill="white">deepcopy(Configuration)</tspan>  ·  one full MRR.PyExec per cross-section (N=2 or 4)  ·  all synchronous on the Qt main thread  ·  on a slow FUSE mount: <tspan fill="#F5C13A" font-weight="700">1–10 seconds of frozen UI per drag</tspan></text>

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  <!-- ─── Bottom "where the debt accumulates" 5-column banner ─── -->

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    <text x="920" y="20" font-size="18" font-weight="700" fill="#8C3A00" text-anchor="middle">Where the debt accumulates — five patterns scientists perceive as "Qt leaking into the reduction"</text>



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      <text x="15" y="22" font-size="13.5" font-weight="700" fill="#002E5D">●  Synchronous reduction</text>

      <text x="15" y="42" font-size="11.5" fill="#3E2C00">Steps 6–7 run on the Qt event-loop thread.</text>

      <text x="15" y="58" font-size="11.5" fill="#3E2C00">No QThread, no async — the UI freezes during</text>

      <text x="15" y="74" font-size="11.5" fill="#3E2C00">every reduction.</text>



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      <text x="385" y="22" font-size="13.5" font-weight="700" fill="#002E5D">●  Deepcopy chain</text>

      <text x="385" y="42" font-size="11.5" fill="#3E2C00">Configuration copied on every UI event.</text>

      <text x="385" y="58" font-size="11.5" fill="#3E2C00">Class attributes bypass the copy — still</text>

      <text x="385" y="74" font-size="11.5" fill="#3E2C00">shared globals across runs.</text>



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      <text x="755" y="22" font-size="13.5" font-weight="700" fill="#002E5D">●  Class-attribute globals</text>

      <text x="755" y="42" font-size="11.5" fill="#3E2C00">22 "global options" live on the class itself.</text>

      <text x="755" y="58" font-size="11.5" fill="#3E2C00">Changing one in the UI retroactively</text>

      <text x="755" y="74" font-size="11.5" fill="#3E2C00">affects every loaded run.</text>



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      <text x="1125" y="22" font-size="13.5" font-weight="700" fill="#002E5D">●  Qt signal timing</text>

      <text x="1125" y="42" font-size="11.5" fill="#3E2C00" font-family="monospace">valueChanged</text>

      <text x="1220" y="42" font-size="11.5" fill="#3E2C00"> vs </text>

      <text x="1250" y="42" font-size="11.5" fill="#3E2C00" font-family="monospace">editingFinished</text>

      <text x="1125" y="58" font-size="11.5" fill="#3E2C00">fire at different moments. Changing which</text>

      <text x="1125" y="74" font-size="11.5" fill="#3E2C00">signal is connected can change results.</text>



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      <text x="1495" y="22" font-size="13.5" font-weight="700" fill="#002E5D">●  Widget lifecycle</text>

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      <text x="1495" y="58" font-size="11.5" fill="#3E2C00">Row index −1 → negative-index corruption.</text>

      <text x="1495" y="74" font-size="11.5" fill="#3E2C00">One SEGV fix committed 2026-03-21.</text>

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  <!-- Footer -->

  <rect x="0" y="1055" width="1920" height="25" fill="#001A35"/>

  <text x="40" y="1073" font-size="12" fill="#6A90B0">Sources: 12-parameter-propagation-and-qt-leakage.md §1–§5 · quicknxsv2 src/quicknxs/interfaces/event_handlers/main_handler.py · data_handling/data_set.py</text>

  <text x="1880" y="1073" font-size="12" fill="#6A90B0" text-anchor="end">Reflectometry Hack-a-thon 2026 · slide 5 of 8</text>

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