Joseph Doherty
826312befe
Clears CommentChecker findings in src/ (3,280 -> 209, the remainder being false positives like PLC-5/IEEE-754/M0.0) by adding missing summaries/params/returns, normalising inheritdoc usage, and removing Gitea/review tracking IDs while keeping the rationale they annotated. Comment-only: comment-stripped sources are identical to the parent commit.
44 lines
2.5 KiB
C#
44 lines
2.5 KiB
C#
namespace ZB.MOM.WW.OtOpcUa.OpcUaServer;
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/// <summary>
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/// The opt-in <c>ServerHistorian:EventReadHorizon</c> — HistoryReadEvents never reads events older than
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/// <c>now − horizon</c>. Off (<see cref="TimeSpan.Zero"/>, the default) a read is exact down to whatever its window says,
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/// which on the Gateway means a reverse / end-only read walked back with forward reads proves "nothing older" with one
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/// read down to the Unix epoch — ~3.8 s live on <c>Runtime.dbo.Events</c>, and an unfiltered one can hit the
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/// gateway's 30 s SQL timeout. A forward read whose StartTime is far in the past costs the same on that table. The
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/// horizon bounds both, at a stated price: events older than it are not returned, in either direction, on any backend.
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/// </summary>
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internal static class EventHorizon
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{
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/// <summary>
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/// Raises the EARLIER bound of a fresh events window to the horizon's floor (<c>now − horizon</c>, inclusive): the
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/// start of a forward <c>[start, end)</c> window, the exclusive lower end of a reverse <c>(end, start]</c> one.
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/// </summary>
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/// <param name="startUtc">The window start (the later bound of a reverse read).</param>
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/// <param name="endUtc">The window end (the exclusive earlier bound of a reverse read).</param>
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/// <param name="reverse">Whether the read is newest-first (<c>start > end</c>).</param>
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/// <param name="horizon">The horizon; non-positive = none (nothing changes).</param>
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/// <param name="nowUtc">Now.</param>
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/// <returns><c>false</c> when the whole window lies before the floor — the read is empty and must not be sent.</returns>
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public static bool TryClamp(ref DateTime startUtc, ref DateTime endUtc, bool reverse, TimeSpan horizon, DateTime nowUtc)
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{
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if (horizon <= TimeSpan.Zero) return true;
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var floor = nowUtc.Ticks - DateTime.MinValue.Ticks > horizon.Ticks
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? new DateTime(nowUtc.Ticks - horizon.Ticks, DateTimeKind.Utc)
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: new DateTime(0, DateTimeKind.Utc);
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if (floor.Ticks == 0) return true;
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if (reverse)
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{
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if (startUtc < floor) return false; // (end, start] lies wholly before the floor
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var below = floor.AddTicks(-1); // exclusive lower end ⇒ the floor instant itself is read
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if (endUtc < below) endUtc = below;
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return true;
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}
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if (endUtc <= floor) return false; // [start, end) lies wholly before the floor
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if (startUtc < floor) startUtc = floor;
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return true;
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}
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}
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