Joseph Doherty
1a2856526a
Comments described the *history* of how the code arrived (phase numbers, wave IDs, review IDs, dated TODOs) instead of what it does today. That scaffolding rotted as the codebase evolved. Cleaned 60 source files + .gitignore; behaviour unchanged (387/387 tests still pass). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
39 lines
1.9 KiB
C#
39 lines
1.9 KiB
C#
namespace Mbproxy.Proxy.Multiplexing;
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/// <summary>
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/// One upstream party interested in a single backend round-trip. Carries the upstream
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/// pipe to deliver the response to AND the original MBAP TxId that the party sent — the
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/// multiplexer must rewrite the response's MBAP TxId back to <see cref="OriginalTxId"/>
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/// before handing the frame to the pipe, so each upstream sees the proxy as transparent.
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///
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/// <para>Read coalescing fans out a single backend response to multiple upstream parties
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/// via this record. Do not collapse this into a single field on
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/// <see cref="InFlightRequest"/>.</para>
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/// </summary>
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internal sealed record InterestedParty(UpstreamPipe Pipe, ushort OriginalTxId);
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/// <summary>
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/// Per-backend-request correlation record. Stored in <see cref="CorrelationMap"/> keyed
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/// by the proxy-assigned TxId; looked up by the backend reader task to:
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/// <list type="bullet">
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/// <item><description>Restore each interested party's original MBAP TxId before forwarding
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/// the response upstream (transparent multiplexing contract).</description></item>
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/// <item><description>Provide the BCD rewriter with the originating request's
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/// <c>StartAddress</c> / <c>Qty</c> for FC03/FC04 response decoding — the response
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/// PDU itself does not carry the start address.</description></item>
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/// <item><description>Measure backend round-trip time via <see cref="SentAtUtc"/>.</description></item>
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/// </list>
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///
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/// <para>The <see cref="InterestedParties"/> list shape is the load-bearing seam that
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/// read coalescing uses to fan out a single PLC response to multiple upstream clients.
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/// Reviewer note: do <i>not</i> simplify back to a single <c>UpstreamPipe</c> field.</para>
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/// </summary>
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internal sealed record InFlightRequest(
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byte UnitId,
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byte Fc,
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ushort StartAddress,
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ushort Qty,
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IReadOnlyList<InterestedParty> InterestedParties,
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DateTimeOffset SentAtUtc,
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int ResolvedCacheTtlMs = 0);
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