Class PaletteLoadCoordinator

Namespace: EncDotNet.S100.Portrayals

Assembly: EncDotNet.S100.Portrayals.dll

Centralizes the concurrency-safe, one-shot colour-palette load protocol shared by every portrayal catalogue.

public static class PaletteLoadCoordinator

Inheritance: object

PaletteLoadCoordinator

Inherited Members: object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

A single IPortrayalAssetCache is shared per product spec across every dataset of that spec (for example, every cell of one S-101 exchange set), and those datasets load on separate threads. Two earlier defects followed from loading palettes ad hoc:

Cache poisoning. Marking PalettesLoaded before the load completed meant a cancelled or aborted load (routine in the viewer when a pan/zoom/reload cancels the in-flight render) left the shared cache flagged loaded-but-empty, so every later palette lookup failed.
Races. Concurrent loaders wrote the non-thread-safe palette dictionary simultaneously, or a second loader observed it half-populated.

This helper serializes the load through PaletteLoadGate with double-checked locking and commits PalettesLoaded only after the load runs to completion without being cancelled. See issue #321.

Methods

EnsureLoadedAsync(IPortrayalAssetCache, Func<CancellationToken, ValueTask>, Action, CancellationToken)

Ensures the shared cache's palettes are loaded exactly once, safely under concurrency, retrying after a cancelled attempt rather than poisoning the cache.

public static ValueTask EnsureLoadedAsync(IPortrayalAssetCache cache, Func<CancellationToken, ValueTask> loadInto, Action onLoaded, CancellationToken cancellationToken = default)

Parameters

cache IPortrayalAssetCache: The shared per-spec asset cache.
loadInto Func<CancellationToken, ValueTask>: Populates Palettes. Invoked at most once per successful load while the gate is held. Must not set PalettesLoaded itself.
onLoaded Action: Applies the catalogue's active-palette selection (typically Day). Called after the load completes and on the already-loaded fast path.
cancellationToken CancellationToken: A cancellation token.

Returns