57 lines
2.3 KiB
Text
57 lines
2.3 KiB
Text
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// Cross-thread architecture and data-visibility handoff.
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// Render: dot -Tsvg thread-handoff.dot -o thread-handoff.svg
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//
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// One direction of data flow: the Proactor thread reads file blocks into the
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// ring of buffers and publishes a ready frame through the single atomic baton
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// `toDisplay_`; the GUI thread picks it up, uploads it to the GPU, and hands
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// the slot back. The release/acquire pairs on the baton carry buffer-content
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// visibility in both directions.
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digraph handoff {
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rankdir=LR;
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bgcolor="transparent";
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compound=true;
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fontname="sans-serif";
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node [fontname="sans-serif", fontsize=11];
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edge [fontname="sans-serif", fontsize=10];
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file [shape=cylinder, fillcolor="#eeeeee", style=filled, label="demovideo.raw"];
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subgraph cluster_proactor {
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label=" »Proactor« thread — playVideo() loop ";
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labeljust="l";
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style="filled,rounded"; fillcolor="#eef4ff"; color="#7092c0"; fontsize=12;
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wait [shape=box, style="rounded,filled", fillcolor="#ffffff",
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label="io_uring_wait_cqe()\n(blocking)"];
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timer [shape=box, style="rounded,filled", fillcolor="#ffedcc",
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label="frame-beat timer\n20 ms · multishot"];
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ring [shape=record, style=filled, fillcolor="#ffffff",
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label="ring buffers\ (RING_SIZ)|<s0>slot|<s1>slot|<s2>slot|<s3>…"];
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}
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subgraph cluster_gui {
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label=" GTK / GUI thread ";
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labeljust="l";
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style="filled,rounded"; fillcolor="#eefaee"; color="#6bab6b"; fontsize=12;
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disp [shape=box, style="rounded,filled", fillcolor="#ffffff",
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label="EglDisplay::displayFrame()\nretrieveFrame() / completedFrame()"];
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gpu [shape=box, style="rounded,filled", fillcolor="#ffffff",
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label="GPU texture\n(glTexImage2D → draw)"];
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}
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baton [shape=box, style="filled", fillcolor="#e7d8ff", penwidth=1.6,
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label="toDisplay_\nstd::atomic<Buffer*>"];
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file -> ring [label="io_uring read", lhead=cluster_proactor];
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timer -> wait [style=dotted, label="CQE (TICK_TAG)"];
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ring -> baton [label="publish\nstore(release)", color="#5a2ca0", fontcolor="#5a2ca0"];
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baton -> disp [label="retrieveFrame\nload(acquire)", color="#5a2ca0", fontcolor="#5a2ca0"];
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disp -> gpu [label="upload + draw"];
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disp -> baton [label="completedFrame\nstore(nullptr, release)",
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style=dashed, color="#3a7a3a", fontcolor="#3a7a3a"];
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{ rank=same; baton; }
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}
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