Ichthyostega
703e60c85a
''Review supported by Claude Code'' Control flow logic was scrutinised, and a race identified in the solution to pass on the display action to the GUI thread. Reconsidering the design, cross-thread synchronisation is now hinged rather on a single atomic buffer pointer, where the GUI thread notifies back completion of display work by setting that pointer to NULL. Overall this simplifies the control logic ---- As an aside, I setup an outline of topics for documentation in `DemoSpec.txt` and then instructed Claude to fill in the paragraphs, based on insight gained as part of the code validation / review. Furthermore, I requested to generate some diagrams that could be useful later when preparting the presentation
34 lines
1.3 KiB
Text
34 lines
1.3 KiB
Text
// Buffer-slot state engine of the io_uring video demo.
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// Render: dot -Tsvg state-engine.dot -o state-engine.svg
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//
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// The BuffState of each ring slot is written and read ONLY by the Proactor
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// thread; the single SHOW->FREE transition is triggered by the GUI thread
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// clearing the atomic baton (toDisplay_), but observed and enacted here.
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digraph BuffState {
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rankdir=LR;
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bgcolor="transparent";
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labelloc="t";
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fontname="sans-serif";
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fontsize=14;
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label="Life-cycle of one buffer »slot«";
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node [shape=circle, fixedsize=true, width=0.9,
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fontname="sans-serif", fontsize=12, style=filled, penwidth=1.4];
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edge [fontname="sans-serif", fontsize=10];
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FREE [fillcolor="#dbe9ff"];
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READ [fillcolor="#ffedcc"];
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FEED [fillcolor="#d8f0d8"];
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SHOW [fillcolor="#e7d8ff"];
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STOP [shape=doublecircle, width=0.85, fillcolor="#ffd6d6"];
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FREE -> READ [label=" submit read\l addNextReadSubmissions()\l"];
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READ -> FEED [label=" read completed OK\l handleCompletedRead()\l"];
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READ -> STOP [label=" short read / EOF ", fontcolor="#a00000", color="#a00000"];
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FEED -> SHOW [label=" publish frame\l maybeDisplayFrame()\l"];
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SHOW -> FREE [label=" GUI released frame\l (toDisplay_ == nullptr)\l",
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fontcolor="#5a2ca0", color="#5a2ca0", constraint=false];
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{ rank=same; FREE; }
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}
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