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ersatztv/ErsatzTV.Application/Playouts/Commands/DeletePlayoutHandler.cs
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timothyandClaude Opus 4.8 a1bd303cce
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fix(app): post-commit side effects on CancellationToken.None + guide-xml/empty-list hardening (#254)
Backend mutation-hardening cluster from the 2026-07-11 mutation-safety audit
sweep (adversarial-reviewer #22/#23), the parallel-safe backend-isolated slice.

audit#22 F4 — standardize post-commit enqueues on CancellationToken.None:
20 command handlers under MediaCollections/, ProgramSchedules/, Playouts/,
Channels/ threaded the request cancellationToken into work that runs AFTER
SaveChangesAsync commits (WriteAsync rebuild/refresh enqueues, mediator.Publish,
reindex, cache Refresh, and post-commit lookups that gate an enqueue). A late
client-disconnect then turns an already-durable commit into a thrown request AND
drops the side effect. Generalizes the #251 deco-handler fix. Excludes
BuildPlayoutHandler (worker/background token, not a client-disconnect token),
the config/FFmpeg multi-upsert handlers (partial-commit case, separate
follow-up), and response-projection reloads (correctly keep the request token).

audit#22 F2 — DeleteChannelHandler/DeletePlayoutHandler now delete the channel
guide {number}.xml through IFileSystem.File.Delete (observable under
MockFileSystem) and BEFORE the commit (a post-commit delete orphans the xml on a
crash; the xml is regenerable on demand, so pre-commit delete is the safe order).

audit#23 F4 — ReplacePlayoutAlternateScheduleItemsHandler rejects an empty item
list in the handler (not only the controller pre-guard) so a direct caller can't
trip the Max()-on-empty crash.

Docs: api-conventions.md §7a (post-commit token convention + boundaries),
decisions.md entry (rationale, sweep scope, #253 PR2-4 coordination note).
Tests: guide-cache-delete-through-FS for both delete handlers, empty-list guard.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-11 17:42:45 +02:00

57 lines
2.4 KiB
C#

using System.IO.Abstractions;
using System.Threading.Channels;
using ErsatzTV.Application.Channels;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Errors;
using ErsatzTV.Core.Notifications;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.Extensions;
using Microsoft.EntityFrameworkCore;
namespace ErsatzTV.Application.Playouts;
public class DeletePlayoutHandler(
ChannelWriter<IBackgroundServiceRequest> workerChannel,
IDbContextFactory<TvContext> dbContextFactory,
IFileSystem fileSystem,
IMediator mediator)
: IRequestHandler<DeletePlayout, Either<BaseError, Unit>>
{
public async Task<Either<BaseError, Unit>> Handle(DeletePlayout request, CancellationToken cancellationToken)
{
await using TvContext dbContext = await dbContextFactory.CreateDbContextAsync(cancellationToken);
Option<Playout> maybePlayout = await dbContext.Playouts
.Include(p => p.Channel)
.SelectOneAsync(p => p.Id, p => p.Id == request.PlayoutId, cancellationToken);
foreach (Playout playout in maybePlayout)
{
// Delete the guide cache file through the filesystem abstraction (observable under a
// MockFileSystem) and BEFORE the commit: deleting after commit orphans {number}.xml if the
// process crashes in between. The guide xml is regenerable on demand, so losing it pre-commit
// is safe (#254).
string cacheFile = Path.Combine(FileSystemLayout.ChannelGuideCacheFolder, $"{playout.Channel.Number}.xml");
if (fileSystem.File.Exists(cacheFile))
{
fileSystem.File.Delete(cacheFile);
}
dbContext.Playouts.Remove(playout);
await dbContext.SaveChangesAsync(cancellationToken);
// post-commit side effects run on CancellationToken.None so a late request cancellation can't
// abort them after the delete committed (#254)
// refresh channel list to remove channel that has no playout
await workerChannel.WriteAsync(new RefreshChannelList(), CancellationToken.None);
await mediator.Publish(new PlayoutUpdatedNotification(playout.Id, false), CancellationToken.None);
}
return maybePlayout
.Map(_ => Unit.Default)
.ToEither<BaseError>(new NotFoundError($"Playout {request.PlayoutId} does not exist."));
}
}