Fix download timeouts not marking the downloaded file as failed

References #256

app/Desktop/Arguments.cs

@@ -15,6 +15,7 @@ sealed class Arguments {
 	public string? DatabaseFile { get; }
 	public ushort? ServerPort { get; }
 	public string? ServerToken { get; }
+	public byte? ConcurrentDownloads { get; }
 
 	public Arguments(IReadOnlyList<string> args) {
 		for (int i = FirstArgument; i < args.Count; i++) {
@@ -50,11 +51,11 @@ sealed class Arguments {
 					continue;
 
 				case "-port": {
-					if (ushort.TryParse(value, out var port)) {
+					if (!ushort.TryParse(value, out var port)) {
-						ServerPort = port;
+						Log.Warn("Invalid port number: " + value);
 					}
 					else {
-						Log.Warn("Invalid port number: " + value);
+						ServerPort = port;
 					}
 
 					continue;
@@ -64,6 +65,20 @@ sealed class Arguments {
 					ServerToken = value;
 					continue;
 				
+				case "-concurrentdownloads":
+					if (!ulong.TryParse(value, out var concurrentDownloads) || concurrentDownloads == 0) {
+						Log.Warn("Invalid concurrent downloads count: " + value);
+					}
+					else if (concurrentDownloads > 10) {
+						Log.Warn("Limiting concurrent downloads to 10");
+						ConcurrentDownloads = 10;
+					}
+					else {
+						ConcurrentDownloads = (byte) concurrentDownloads;
+					}
+					
+					continue;
+
 				default:
 					Log.Warn("Unknown command line argument: " + key);
 					break;

app/Desktop/Main/MainWindowModel.cs

@@ -30,6 +30,7 @@ sealed partial class MainWindowModel : ObservableObject, IAsyncDisposable {
 	private MainContentScreenModel? mainContentScreenModel;
 
 	private readonly Window window;
+	private readonly int? concurrentDownloads;
 
 	private State? state;
 
@@ -73,6 +74,8 @@ sealed partial class MainWindowModel : ObservableObject, IAsyncDisposable {
 		if (args.ServerToken != null) {
 			ServerConfiguration.Token = args.ServerToken;
 		}
+		
+		concurrentDownloads = args.ConcurrentDownloads;
 	}
 
 	private async void OnDatabaseSelected(object? sender, IDatabaseFile db) {
@@ -80,7 +83,7 @@ sealed partial class MainWindowModel : ObservableObject, IAsyncDisposable {
 		
 		await DisposeState();
 		
-		state = new State(db);
+		state = new State(db, concurrentDownloads);
 
 		try {
 			await state.Server.Start(ServerConfiguration.Port, ServerConfiguration.Token);

app/Server/Download/Downloader.cs

@@ -11,16 +11,18 @@ public sealed class Downloader {
 	public bool IsDownloading => current != null;
 	
 	private readonly IDatabaseFile db;
+	private readonly int? concurrentDownloads;
 	private readonly SemaphoreSlim semaphore = new (1, 1);
 	
-	internal Downloader(IDatabaseFile db) {
+	internal Downloader(IDatabaseFile db, int? concurrentDownloads) {
 		this.db = db;
+		this.concurrentDownloads = concurrentDownloads;
 	}
 
 	public async Task<IObservable<DownloadItem>> Start(DownloadItemFilter filter) {
 		await semaphore.WaitAsync();
 		try {
-			current ??= new DownloaderTask(db, filter);
+			current ??= new DownloaderTask(db, filter, concurrentDownloads);
 			return current.FinishedItems;
 		} finally {
 			semaphore.Release();

app/Server/Download/DownloaderTask.cs

@@ -15,10 +15,14 @@ namespace DHT.Server.Download;
 sealed class DownloaderTask : IAsyncDisposable {
 	private static readonly Log Log = Log.ForType<DownloaderTask>();
 
-	private const int DownloadTasks = 4;
+	private const int DefaultConcurrentDownloads = 4;
 	private const int QueueSize = 25;
 	private const string UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36";
 
+	private static int GetDownloadTaskCount(int? concurrentDownloads) {
+		return Math.Max(1, concurrentDownloads ?? DefaultConcurrentDownloads);
+	}
+
 	private readonly Channel<DownloadItem> downloadQueue = Channel.CreateBounded<DownloadItem>(new BoundedChannelOptions(QueueSize) {
 		SingleReader = false,
 		SingleWriter = true,
@@ -38,12 +42,12 @@ sealed class DownloaderTask : IAsyncDisposable {
 
 	public IObservable<DownloadItem> FinishedItems => finishedItemPublisher;
 
-	internal DownloaderTask(IDatabaseFile db, DownloadItemFilter filter) {
+	internal DownloaderTask(IDatabaseFile db, DownloadItemFilter filter, int? concurrentDownloads) {
 		this.db = db;
 		this.filter = filter;
 		this.cancellationToken = cancellationTokenSource.Token;
 		this.queueWriterTask = Task.Run(RunQueueWriterTask);
-		this.downloadTasks = Enumerable.Range(1, DownloadTasks).Select(taskIndex => Task.Run(() => RunDownloadTask(taskIndex))).ToArray();
+		this.downloadTasks = Enumerable.Range(1, GetDownloadTaskCount(concurrentDownloads)).Select(taskIndex => Task.Run(() => RunDownloadTask(taskIndex))).ToArray();
 	}
 
 	private async Task RunQueueWriterTask() {
@@ -74,8 +78,12 @@ sealed class DownloaderTask : IAsyncDisposable {
 			try {
 				var downloadedBytes = await client.GetByteArrayAsync(item.DownloadUrl, cancellationToken);
 				await db.Downloads.AddDownload(item.ToSuccess(downloadedBytes));
-			} catch (OperationCanceledException) {
+			} catch (OperationCanceledException e) when (e.CancellationToken == cancellationToken) {
 				// Ignore.
+			} catch (TaskCanceledException e) {
+				// HttpClient request timed out.
+				await db.Downloads.AddDownload(item.ToFailure());
+				log.Error(e.Message);
 			} catch (HttpRequestException e) {
 				await db.Downloads.AddDownload(item.ToFailure(e.StatusCode));
 				log.Error(e);

app/Server/State.cs

@@ -6,18 +6,12 @@ using DHT.Server.Service;
 
 namespace DHT.Server;
 
-public sealed class State : IAsyncDisposable {
+public sealed class State(IDatabaseFile db, int? concurrentDownloads) : IAsyncDisposable {
-	public static State Dummy { get; } = new (DummyDatabaseFile.Instance);
+	public static State Dummy { get; } = new (DummyDatabaseFile.Instance, null);
 	
-	public IDatabaseFile Db { get; }
+	public IDatabaseFile Db { get; } = db;
-	public Downloader Downloader { get; }
+	public Downloader Downloader { get; } = new (db, concurrentDownloads);
-	public ServerManager Server { get; }
+	public ServerManager Server { get; } = new (db);
-
-	public State(IDatabaseFile db) {
-		Db = db;
-		Downloader = new Downloader(db);
-		Server = new ServerManager(db);
-	}
 
 	public async ValueTask DisposeAsync() {
 		await Downloader.Stop();