From eefbb581ef59fb114da3ec818179e40c6925714a Mon Sep 17 00:00:00 2001
From: Jordan Brown <Cyberboss@users.noreply.github.com>
Date: Mon, 25 May 2020 22:27:28 -0400
Subject: [PATCH] DisposeAndNullControllers from a locked context

---
 .../Components/Watchdog/BasicWatchdog.cs        |  2 +-
 .../Components/Watchdog/ExperimentalWatchdog.cs |  6 ++----
 .../Components/Watchdog/WatchdogBase.cs         | 17 ++++++++++++++++-
 .../Components/Watchdog/WindowsWatchdog.cs      |  4 ++--
 4 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/Tgstation.Server.Host/Components/Watchdog/BasicWatchdog.cs b/src/Tgstation.Server.Host/Components/Watchdog/BasicWatchdog.cs
index 13c96f350a..e3e8968fd8 100644
--- a/src/Tgstation.Server.Host/Components/Watchdog/BasicWatchdog.cs
+++ b/src/Tgstation.Server.Host/Components/Watchdog/BasicWatchdog.cs
@@ -192,7 +192,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 			};
 
 		/// <inheritdoc />
-		protected override void DisposeAndNullControllers()
+		protected override void DisposeAndNullControllersImpl()
 		{
 			Server?.Dispose();
 			Server = null;
diff --git a/src/Tgstation.Server.Host/Components/Watchdog/ExperimentalWatchdog.cs b/src/Tgstation.Server.Host/Components/Watchdog/ExperimentalWatchdog.cs
index 02daf7d157..6547ef6d62 100644
--- a/src/Tgstation.Server.Host/Components/Watchdog/ExperimentalWatchdog.cs
+++ b/src/Tgstation.Server.Host/Components/Watchdog/ExperimentalWatchdog.cs
@@ -392,10 +392,8 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		}
 #pragma warning restore CA1502
 
-		/// <summary>
-		/// Call <see cref="IDisposable.Dispose"/> on <see cref="alphaServer"/> and <see cref="bravoServer"/> and set them to <see langword="null"/>
-		/// </summary>
-		protected override void DisposeAndNullControllers()
+		/// <inheritdoc />
+		protected override void DisposeAndNullControllersImpl()
 		{
 			alphaServer?.Dispose();
 			alphaServer = null;
diff --git a/src/Tgstation.Server.Host/Components/Watchdog/WatchdogBase.cs b/src/Tgstation.Server.Host/Components/Watchdog/WatchdogBase.cs
index 74b3e06371..66837c302a 100644
--- a/src/Tgstation.Server.Host/Components/Watchdog/WatchdogBase.cs
+++ b/src/Tgstation.Server.Host/Components/Watchdog/WatchdogBase.cs
@@ -112,6 +112,11 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// </summary>
 		readonly IRestartRegistration restartRegistration;
 
+		/// <summary>
+		/// <see langword="lock"/> <see cref="object"/> used for <see cref="DisposeAndNullControllers"/>.
+		/// </summary>
+		readonly object controllerDisposeLock;
+
 		/// <summary>
 		/// If the <see cref="WatchdogBase"/> should <see cref="LaunchImplNoLock(bool, bool, DualReattachInformation, CancellationToken)"/> in <see cref="StartAsync(CancellationToken)"/>
 		/// </summary>
@@ -201,6 +206,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 			ActiveLaunchParameters = initialLaunchParameters;
 			releaseServers = false;
 			ActiveParametersUpdated = new TaskCompletionSource<object>();
+			controllerDisposeLock = new object();
 
 			restartRegistration = serverControl.RegisterForRestart(this);
 			try
@@ -463,7 +469,16 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// <summary>
 		/// Call <see cref="IDisposable.Dispose"/> and null the fields for all <see cref="ISessionController"/>s and set <see cref="Running"/> to <see langword="false"/>.
 		/// </summary>
-		protected abstract void DisposeAndNullControllers();
+		protected abstract void DisposeAndNullControllersImpl();
+
+		/// <summary>
+		/// Wrapper for <see cref="DisposeAndNullControllersImpl"/> under a locked context.
+		/// </summary>
+		protected void DisposeAndNullControllers()
+		{
+			lock (controllerDisposeLock)
+				DisposeAndNullControllersImpl();
+		}
 
 		/// <summary>
 		/// Get the active <see cref="ISessionController"/>.
diff --git a/src/Tgstation.Server.Host/Components/Watchdog/WindowsWatchdog.cs b/src/Tgstation.Server.Host/Components/Watchdog/WindowsWatchdog.cs
index 895347f4a6..730ced06b9 100644
--- a/src/Tgstation.Server.Host/Components/Watchdog/WindowsWatchdog.cs
+++ b/src/Tgstation.Server.Host/Components/Watchdog/WindowsWatchdog.cs
@@ -101,9 +101,9 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		}
 
 		/// <inheritdoc />
-		protected override void DisposeAndNullControllers()
+		protected override void DisposeAndNullControllersImpl()
 		{
-			base.DisposeAndNullControllers();
+			base.DisposeAndNullControllersImpl();
 
 			// If we reach this point, we can guarantee PrepServerForLaunch will be called before starting again.
 			activeSwappable = null;