timothy
e3645a2840
Extends MediaServerReconciliationGuard (#477) with a second deterministic refusal: when the enumeration that produced the incoming set silently dropped items whose projection THREW, the file-not-found sweep is refused. A dropped item the server did return is indistinguishable from a deletion at the reconcile step, so a projection regression could otherwise mass-flag a healthy library FileNotFound (which EmptyTrash then deletes permanently). Deliberate guard-clause skips (STRM files, virtual items, unsupported types) are explicitly NOT failures and never suppress a sweep — counting them would permanently disable reconciliation for any library holding a single STRM file. The ratio / missing-fraction threshold is REJECTED, not deferred: it is a two-sided heuristic with no tunable default and no telemetry, and the failure it approximates is exactly observable via the projection-failure count (a genuine bulk deletion produces zero failures). Seam is deliberately narrow — the private ProjectTo* contract inside each api client changed from Option<T> to MediaServerProjectionResult<T> (projected/skipped/failed), the paged helper counts IsFailure in one place, and the scanner reads it through an optional trailing MediaServerProjectionFailureCounter on only the five library-level methods that feed a sweep. The counter is per-enumeration state created by the scanner, never a field on an api client. fixes #484
50 lines
2.4 KiB
C#
50 lines
2.4 KiB
C#
namespace ErsatzTV.Core.Metadata;
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// #484: a media-server API client maps each item the server returned through a private projection. That
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// projection has TWO reasons to produce nothing, and conflating them is dangerous:
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//
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// - Skipped — a deliberate guard clause (a virtual/non-FileSystem item, a STRM file, an unsupported
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// item type). The item is permanently and expectedly absent from the incoming set; a
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// library containing one STRM file produces a Skipped on every single scan, forever.
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// - Failed — the projection threw and was swallowed by a `catch { LogWarning; }`. The server DID
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// return the item; we simply could not build it. At the reconcile step that is
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// indistinguishable from a deletion, so a projection regression can mass-flag healthy
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// items FileNotFound (which EmptyTrash then deletes permanently).
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//
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// Only Failed may suppress the reconciliation sweep (see MediaServerReconciliationGuard). Treating
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// Skipped as a failure would permanently disable reconciliation for any library holding a single STRM
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// file, so stale rows would accumulate forever — a regression, not a safe default.
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public readonly struct MediaServerProjectionResult<T>
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{
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private MediaServerProjectionResult(Option<T> item, bool isFailure)
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{
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Item = item;
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IsFailure = isFailure;
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}
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public Option<T> Item { get; }
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/// <summary>
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/// True only when the projection threw. A deliberate guard-clause skip is NOT a failure.
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/// </summary>
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public bool IsFailure { get; }
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public static MediaServerProjectionResult<T> Projected(T item) => new(item, false);
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/// <summary>
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/// The server returned an item we deliberately and permanently do not import (virtual item, STRM
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/// file, unsupported type). Expected on every scan; never suppresses a sweep.
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/// </summary>
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public static MediaServerProjectionResult<T> Skipped() => new(Option<T>.None, false);
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/// <summary>
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/// The projection threw and the exception was swallowed. The item exists upstream but is missing
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/// from the incoming set, so the sweep must not run.
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/// </summary>
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public static MediaServerProjectionResult<T> Failed() => new(Option<T>.None, true);
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public static implicit operator MediaServerProjectionResult<T>(T item) => Projected(item);
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public Option<T> ToOption() => Item;
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}
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