Add extra synchronization to IPC state management

Thanks @ezhevita

Author: JustArchi

ArchiSteamFarm/Core/ASF.cs

@@ -355,8 +355,8 @@ private static async Task OnChangedConfigFile(string name) {
 		}
 
 		ArchiLogger.LogGenericInfo(Strings.IPCConfigChanged);
-		await ArchiKestrel.Stop().ConfigureAwait(false);
-		await ArchiKestrel.Start().ConfigureAwait(false);
+
+		await ArchiKestrel.Restart().ConfigureAwait(false);
 	}
 
 	private static async Task OnChangedFile(string name, string fullPath) {

ArchiSteamFarm/IPC/ArchiKestrel.cs

@@ -30,6 +30,7 @@
 using System.Reflection;
 using System.Text.Json;
 using System.Text.Json.Nodes;
+using System.Threading;
 using System.Threading.Tasks;
 using ArchiSteamFarm.Core;
 using ArchiSteamFarm.Helpers.Json;
@@ -64,6 +65,8 @@ internal static class ArchiKestrel {
 
 	internal static HistoryTarget? HistoryTarget { get; private set; }
 
+	private static readonly SemaphoreSlim StateSemaphore = new(1, 1);
+
 	private static WebApplication? WebApplication;
 
 	internal static void OnNewHistoryTarget(HistoryTarget? historyTarget = null) {
@@ -78,43 +81,43 @@ internal static void OnNewHistoryTarget(HistoryTarget? historyTarget = null) {
 		}
 	}
 
-	internal static async Task Start() {
-		if (WebApplication != null) {
-			return;
-		}
-
-		ASF.ArchiLogger.LogGenericInfo(Strings.IPCStarting);
-
-		// Init history logger for /Api/Log usage
-		Logging.InitHistoryLogger();
-
-		WebApplication webApplication = await CreateWebApplication().ConfigureAwait(false);
+	internal static async Task Restart() {
+		await StateSemaphore.WaitAsync().ConfigureAwait(false);
 
 		try {
-			// Start the server
-			await webApplication.StartAsync().ConfigureAwait(false);
-		} catch (Exception e) {
-			ASF.ArchiLogger.LogGenericException(e);
-
-			await webApplication.DisposeAsync().ConfigureAwait(false);
+			await StopInternally().ConfigureAwait(false);
+			await StartInternally().ConfigureAwait(false);
+		} finally {
+			StateSemaphore.Release();
+		}
+	}
 
+	internal static async Task Start() {
+		if (IsRunning) {
 			return;
 		}
 
-		WebApplication = webApplication;
+		await StateSemaphore.WaitAsync().ConfigureAwait(false);
 
-		ASF.ArchiLogger.LogGenericInfo(Strings.IPCReady);
+		try {
+			await StartInternally().ConfigureAwait(false);
+		} finally {
+			StateSemaphore.Release();
+		}
 	}
 
 	internal static async Task Stop() {
-		if (WebApplication == null) {
+		if (!IsRunning) {
 			return;
 		}
 
-		await WebApplication.StopAsync().ConfigureAwait(false);
-		await WebApplication.DisposeAsync().ConfigureAwait(false);
+		await StateSemaphore.WaitAsync().ConfigureAwait(false);
 
-		WebApplication = null;
+		try {
+			await StopInternally().ConfigureAwait(false);
+		} finally {
+			StateSemaphore.Release();
+		}
 	}
 
 	[UnconditionalSuppressMessage("AssemblyLoadTrimming", "IL2026:RequiresUnreferencedCode", Justification = "PathString is a primitive, it's unlikely to be trimmed to the best of our knowledge")]
@@ -519,4 +522,43 @@ private static void OnPrepareResponse(StaticFileResponseContext context) {
 
 		headers.CacheControl = cacheControl;
 	}
+
+	private static async Task StartInternally() {
+		if (WebApplication != null) {
+			return;
+		}
+
+		ASF.ArchiLogger.LogGenericInfo(Strings.IPCStarting);
+
+		// Init history logger for /Api/Log usage
+		Logging.InitHistoryLogger();
+
+		WebApplication webApplication = await CreateWebApplication().ConfigureAwait(false);
+
+		try {
+			// Start the server
+			await webApplication.StartAsync().ConfigureAwait(false);
+		} catch (Exception e) {
+			ASF.ArchiLogger.LogGenericException(e);
+
+			await webApplication.DisposeAsync().ConfigureAwait(false);
+
+			return;
+		}
+
+		WebApplication = webApplication;
+
+		ASF.ArchiLogger.LogGenericInfo(Strings.IPCReady);
+	}
+
+	private static async Task StopInternally() {
+		if (WebApplication == null) {
+			return;
+		}
+
+		await WebApplication.StopAsync().ConfigureAwait(false);
+		await WebApplication.DisposeAsync().ConfigureAwait(false);
+
+		WebApplication = null;
+	}
 }