An overly complicated change to make sure a task is awaited.

- IDisposable moved from IProcessBase to IProcess
- IInstanceManager, IInstance, IWatchdog, and ISessionController switched from IDisposable to IAsyncDisposable
- Process lifetime continuations in SessionController now handled correctly

src/Tgstation.Server.Host/Components/Deployment/DreamMaker.cs

@@ -215,30 +215,34 @@ namespace Tgstation.Server.Host.Components.Deployment
 			job.MinimumSecurityLevel = securityLevel; // needed for the TempDmbProvider
 			var timeoutAt = DateTimeOffset.Now.AddSeconds(timeout);
 
-			using var provider = new TemporaryDmbProvider(ioManager.ResolvePath(job.DirectoryName.ToString()), String.Concat(job.DmeName, DmbExtension), job);
-			using var controller = await sessionControllerFactory.LaunchNew(provider, byondLock, launchParameters, true, cancellationToken).ConfigureAwait(false);
-			var launchResult = await controller.LaunchResult.ConfigureAwait(false);
-
-			var now = DateTimeOffset.Now;
-			if (now < timeoutAt && launchResult.StartupTime.HasValue)
+			ApiValidationStatus validationStatus;
+			using (var provider = new TemporaryDmbProvider(ioManager.ResolvePath(job.DirectoryName.ToString()), String.Concat(job.DmeName, DmbExtension), job))
+			await using (var controller = await sessionControllerFactory.LaunchNew(provider, byondLock, launchParameters, true, cancellationToken).ConfigureAwait(false))
 			{
-				var timeoutTask = Task.Delay(timeoutAt - now, cancellationToken);
+				var launchResult = await controller.LaunchResult.ConfigureAwait(false);
 
-				await Task.WhenAny(controller.Lifetime, timeoutTask).ConfigureAwait(false);
-				cancellationToken.ThrowIfCancellationRequested();
+				var now = DateTimeOffset.Now;
+				if (now < timeoutAt && launchResult.StartupTime.HasValue)
+				{
+					var timeoutTask = Task.Delay(timeoutAt - now, cancellationToken);
+
+					await Task.WhenAny(controller.Lifetime, timeoutTask).ConfigureAwait(false);
+					cancellationToken.ThrowIfCancellationRequested();
+				}
+
+				if (!controller.Lifetime.IsCompleted)
+				{
+					if (requireValidate)
+						throw new JobException(ErrorCode.DreamMakerNeverValidated);
+					await controller.DisposeAsync().ConfigureAwait(false);
+				}
+
+				validationStatus = controller.ApiValidationStatus;
+				logger.LogTrace("API validation status: {0}", validationStatus);
+
+				job.DMApiVersion = controller.DMApiVersion;
 			}
 
-			if (!controller.Lifetime.IsCompleted)
-			{
-				if (requireValidate)
-					throw new JobException(ErrorCode.DreamMakerNeverValidated);
-				controller.Dispose();
-			}
-
-			var validationStatus = controller.ApiValidationStatus;
-			logger.LogTrace("API validation status: {0}", validationStatus);
-
-			job.DMApiVersion = controller.DMApiVersion;
 			switch (validationStatus)
 			{
 				case ApiValidationStatus.RequiresUltrasafe:

src/Tgstation.Server.Host/Components/IInstance.cs

@@ -13,7 +13,7 @@ namespace Tgstation.Server.Host.Components
 	/// <summary>
 	/// For interacting with the instance services
 	/// </summary>
-	public interface IInstance : ILatestCompileJobProvider, IHostedService, IRenameNotifyee, IDisposable
+	public interface IInstance : ILatestCompileJobProvider, IHostedService, IRenameNotifyee, IAsyncDisposable
 	{
 		/// <summary>
 		/// The <see cref="IRepositoryManager"/> for the <see cref="IInstance"/>

src/Tgstation.Server.Host/Components/IInstanceFactory.cs

@@ -1,4 +1,5 @@
 using Microsoft.Extensions.Hosting;
+using System.Threading.Tasks;
 using Tgstation.Server.Host.Components.Interop.Bridge;
 
 namespace Tgstation.Server.Host.Components
@@ -13,7 +14,7 @@ namespace Tgstation.Server.Host.Components
 		/// </summary>
 		/// <param name="bridgeRegistrar">The <see cref="IBridgeRegistrar"/> to use.</param>
 		/// <param name="metadata">The <see cref="Models.Instance"/></param>
-		/// <returns>A new <see cref="IInstance"/></returns>
-		IInstance CreateInstance(IBridgeRegistrar bridgeRegistrar, Models.Instance metadata);
+		/// <returns>A <see cref="Task{TResult}"/> resulting in a new <see cref="IInstance"/>.</returns>
+		Task<IInstance> CreateInstance(IBridgeRegistrar bridgeRegistrar, Models.Instance metadata);
 	}
 }

src/Tgstation.Server.Host/Components/Instance.cs

@@ -133,14 +133,14 @@ namespace Tgstation.Server.Host.Components
 		}
 
 		/// <inheritdoc />
-		public void Dispose()
+		public async ValueTask DisposeAsync()
 		{
 			using (LogContext.PushProperty("Instance", metadata.Id))
 			{
 				timerCts?.Dispose();
 				Configuration.Dispose();
 				Chat.Dispose();
-				Watchdog.Dispose();
+				await Watchdog.DisposeAsync().ConfigureAwait(false);
 				dmbFactory.Dispose();
 				RepositoryManager.Dispose();
 			}

src/Tgstation.Server.Host/Components/InstanceFactory.cs

@@ -192,7 +192,7 @@ namespace Tgstation.Server.Host.Components
 
 		/// <inheritdoc />
 #pragma warning disable CA1506 // TODO: Decomplexify
-		public IInstance CreateInstance(IBridgeRegistrar bridgeRegistrar, Models.Instance metadata)
+		public async Task<IInstance> CreateInstance(IBridgeRegistrar bridgeRegistrar, Models.Instance metadata)
 		{
 			// Create the ioManager for the instance
 			var instanceIoManager = new ResolvingIOManager(ioManager, metadata.Path);
@@ -294,7 +294,7 @@ namespace Tgstation.Server.Host.Components
 						}
 						catch
 						{
-							watchdog.Dispose();
+							await watchdog.DisposeAsync().ConfigureAwait(false);
 							throw;
 						}
 					}

src/Tgstation.Server.Host/Components/InstanceManager.cs

@@ -23,7 +23,7 @@ using Tgstation.Server.Host.System;
 namespace Tgstation.Server.Host.Components
 {
 	/// <inheritdoc />
-	sealed class InstanceManager : IInstanceManager, IRestartHandler, IHostedService, IBridgeRegistrar, IDisposable
+	sealed class InstanceManager : IInstanceManager, IRestartHandler, IHostedService, IBridgeRegistrar, IAsyncDisposable
 	{
 		/// <inheritdoc />
 		public Task Ready => readyTcs.Task;
@@ -114,7 +114,7 @@ namespace Tgstation.Server.Host.Components
 		Version downgradeVersion;
 
 		/// <summary>
-		/// If the <see cref="InstanceManager"/> has been <see cref="Dispose"/>d
+		/// If the <see cref="InstanceManager"/> has been <see cref="DisposeAsync"/>'d
 		/// </summary>
 		bool disposed;
 
@@ -168,7 +168,7 @@ namespace Tgstation.Server.Host.Components
 		}
 
 		/// <inheritdoc />
-		public void Dispose()
+		public async ValueTask DisposeAsync()
 		{
 			lock (instances)
 			{
@@ -178,7 +178,7 @@ namespace Tgstation.Server.Host.Components
 			}
 
 			foreach (var I in instances)
-				I.Value.Dispose();
+				await I.Value.DisposeAsync().ConfigureAwait(false);
 
 			lazyRestartRegistration.Value.Dispose();
 
@@ -261,7 +261,7 @@ namespace Tgstation.Server.Host.Components
 			}
 			finally
 			{
-				instance.Dispose();
+				await instance.DisposeAsync().ConfigureAwait(false);
 			}
 		}
 
@@ -271,7 +271,7 @@ namespace Tgstation.Server.Host.Components
 			if (metadata == null)
 				throw new ArgumentNullException(nameof(metadata));
 			logger.LogInformation("Onlining instance ID {0} ({1}) at {2}", metadata.Id, metadata.Name, metadata.Path);
-			var instance = instanceFactory.CreateInstance(this, metadata);
+			var instance = await instanceFactory.CreateInstance(this, metadata).ConfigureAwait(false);
 			try
 			{
 				lock (instances)
@@ -283,7 +283,7 @@ namespace Tgstation.Server.Host.Components
 			}
 			catch
 			{
-				instance.Dispose();
+				await instance.DisposeAsync().ConfigureAwait(false);
 				throw;
 			}
 

src/Tgstation.Server.Host/Components/Session/ISessionController.cs

@@ -10,7 +10,7 @@ namespace Tgstation.Server.Host.Components.Session
 	/// <summary>
 	/// Handles communication with a DreamDaemon <see cref="IProcess"/>
 	/// </summary>
-	interface ISessionController : IRenameNotifyee, IProcessBase
+	interface ISessionController : IProcessBase, IRenameNotifyee, IAsyncDisposable
 	{
 		/// <summary>
 		/// A <see cref="Task"/> that completes when DreamDaemon starts pumping the windows message queue after loading a .dmb or when it crashes
@@ -70,8 +70,8 @@ namespace Tgstation.Server.Host.Components.Session
 		/// <summary>
 		/// Releases the <see cref="IProcess"/> without terminating it. Also calls <see cref="IDisposable.Dispose"/>
 		/// </summary>
-		/// <returns><see cref="ReattachInformation"/> which can be used to create a new <see cref="ISessionController"/> similar to this one</returns>
-		ReattachInformation Release();
+		/// <returns>A <see cref="Task{TResult}"/> resulting in <see cref="ReattachInformation"/> which can be used to create a new <see cref="ISessionController"/>.</returns>
+		Task<ReattachInformation> Release();
 
 		/// <summary>
 		/// Sends a command to DreamDaemon through /world/Topic()

src/Tgstation.Server.Host/Components/Session/SessionController.cs

@@ -83,7 +83,7 @@ namespace Tgstation.Server.Host.Components.Session
 		public Task<LaunchResult> LaunchResult { get; }
 
 		/// <inheritdoc />
-		public Task<int> Lifetime => process.Lifetime;
+		public Task<int> Lifetime { get; }
 
 		/// <inheritdoc />
 		public Task OnReboot => rebootTcs.Task;
@@ -202,6 +202,7 @@ namespace Tgstation.Server.Host.Components.Session
 		/// <param name="chatTrackingContext">The value of <see cref="chatTrackingContext"/></param>
 		/// <param name="assemblyInformationProvider">The <see cref="IAssemblyInformationProvider"/> for the <see cref="SessionController"/>.</param>
 		/// <param name="logger">The value of <see cref="logger"/></param>
+		/// <param name="postLifetimeCallback">The <see cref="Func{TResult}"/> returning a <see cref="Task"/> to be run after the <paramref name="process"/> ends.</param>
 		/// <param name="startupTimeout">The optional time to wait before failing the <see cref="LaunchResult"/></param>
 		/// <param name="reattached">If this is a reattached session.</param>
 		/// <param name="apiValidate">If this is a DMAPI validation session.</param>
@@ -216,6 +217,7 @@ namespace Tgstation.Server.Host.Components.Session
 			IChatManager chat,
 			IAssemblyInformationProvider assemblyInformationProvider,
 			ILogger<SessionController> logger,
+			Func<Task> postLifetimeCallback,
 			uint? startupTimeout,
 			bool reattached,
 			bool apiValidate)
@@ -253,15 +255,14 @@ namespace Tgstation.Server.Host.Components.Session
 			reattachTopicCts = new CancellationTokenSource();
 			synchronizationLock = new object();
 
-			_ = process.Lifetime.ContinueWith(
-				x =>
-				{
-					lock (synchronizationLock)
-						if (!disposed)
-							reattachTopicCts.Cancel();
-					chatTrackingContext.Active = false;
-				},
-				TaskScheduler.Current);
+			async Task<int> WrapLifetime()
+			{
+				var exitCode = await process.Lifetime.ConfigureAwait(false);
+				await postLifetimeCallback().ConfigureAwait(false);
+				return exitCode;
+			}
+
+			Lifetime = WrapLifetime();
 
 			LaunchResult = GetLaunchResult(
 				assemblyInformationProvider,
@@ -271,58 +272,31 @@ namespace Tgstation.Server.Host.Components.Session
 			logger.LogDebug("Created session controller. CommsKey: {0}, Port: {1}", reattachInformation.AccessIdentifier, Port);
 		}
 
-		/// <summary>
-		/// Finalizes an instance of the <see cref="SessionController"/> class.
-		/// </summary>
-		/// <remarks>The finalizer dispose pattern is necessary so we don't accidentally leak the executable</remarks>
-#pragma warning disable CA1821 // Remove empty Finalizers TODO: remove this when https://github.com/dotnet/roslyn-analyzers/issues/1241 is fixed
-		~SessionController() => Dispose(false);
-#pragma warning restore CA1821 // Remove empty Finalizers
-
 		/// <inheritdoc />
-		public void Dispose()
-		{
-			Dispose(true);
-			GC.SuppressFinalize(this);
-		}
-
-		/// <summary>
-		/// Implements the <see cref="IDisposable"/> pattern
-		/// </summary>
-		/// <param name="disposing">If this function was NOT called by the finalizer</param>
-		void Dispose(bool disposing)
+		public async ValueTask DisposeAsync()
 		{
 			lock (synchronizationLock)
 			{
 				if (disposed)
 					return;
 				disposed = true;
-				logger.LogTrace("Disposing...");
-				if (disposing)
-				{
-					if (!released)
-					{
-						process.Terminate();
-						byondLock.Dispose();
-					}
 
-					process.Dispose();
-					bridgeRegistration?.Dispose();
-					reattachInformation.Dmb?.Dispose(); // will be null when released
-					chatTrackingContext.Dispose();
-					reattachTopicCts.Dispose();
-				}
-				else
+				logger.LogTrace("Disposing...");
+				if (!released)
 				{
-					if (logger != null)
-						logger.LogError("Being disposed via finalizer!");
-					if (!released)
-						if (process != null)
-							process.Terminate();
-						else if (logger != null)
-							logger.LogCritical("Unable to terminate active DreamDaemon session due to finalizer ordering!");
+					process.Terminate();
+					byondLock.Dispose();
 				}
+
+				process.Dispose();
+				bridgeRegistration?.Dispose();
+				reattachInformation.Dmb?.Dispose(); // will be null when released
+				chatTrackingContext.Dispose();
+				reattachTopicCts.Dispose();
 			}
+
+			// finish the async callback
+			await Lifetime.ConfigureAwait(false);
 		}
 
 		/// <summary>
@@ -530,7 +504,7 @@ namespace Tgstation.Server.Host.Components.Session
 		}
 
 		/// <summary>
-		/// Throws an <see cref="ObjectDisposedException"/> if <see cref="Dispose(bool)"/> has been called
+		/// Throws an <see cref="ObjectDisposedException"/> if <see cref="DisposeAsync"/> has been called
 		/// </summary>
 		void CheckDisposed()
 		{
@@ -542,7 +516,7 @@ namespace Tgstation.Server.Host.Components.Session
 		public void EnableCustomChatCommands() => chatTrackingContext.Active = DMApiAvailable;
 
 		/// <inheritdoc />
-		public ReattachInformation Release()
+		public async Task<ReattachInformation> Release()
 		{
 			CheckDisposed();
 
@@ -550,7 +524,7 @@ namespace Tgstation.Server.Host.Components.Session
 			var tmpProvider = reattachInformation.Dmb;
 			reattachInformation.Dmb = null;
 			released = true;
-			Dispose();
+			await DisposeAsync().ConfigureAwait(false);
 			byondLock.DoNotDeleteThisSession();
 			tmpProvider.KeepAlive();
 			reattachInformation.Dmb = tmpProvider;

src/Tgstation.Server.Host/Components/Session/SessionControllerFactory.cs

@@ -297,22 +297,20 @@ namespace Tgstation.Server.Host.Components.Session
 					}
 
 					// Log DD output
-					_ = process.Lifetime.ContinueWith(
-							async x =>
-							{
-								try
-								{
-									var ddOutput = await GetDDOutput().ConfigureAwait(false);
-									logger.LogTrace(
-										"DreamDaemon Output:{0}{1}",
-										Environment.NewLine, ddOutput);
-								}
-								catch (Exception ex)
-								{
-									logger.LogWarning("Error reading DreamDaemon output: {0}", ex);
-								}
-							},
-							TaskScheduler.Current);
+					async Task PostLifetime()
+					{
+						try
+						{
+							var ddOutput = await GetDDOutput().ConfigureAwait(false);
+							logger.LogTrace(
+								"DreamDaemon Output:{0}{1}",
+								Environment.NewLine, ddOutput);
+						}
+						catch (Exception ex)
+						{
+							logger.LogWarning("Error reading DreamDaemon output: {0}", ex);
+						}
+					}
 
 					try
 					{
@@ -342,6 +340,7 @@ namespace Tgstation.Server.Host.Components.Session
 							chat,
 							assemblyInformationProvider,
 							loggerFactory.CreateLogger<SessionController>(),
+							PostLifetime,
 							launchParameters.StartupTimeout,
 							false,
 							apiValidate);
@@ -417,6 +416,7 @@ namespace Tgstation.Server.Host.Components.Session
 							chat,
 							assemblyInformationProvider,
 							loggerFactory.CreateLogger<SessionController>(),
+							() => Task.CompletedTask,
 							null,
 							true,
 							false);

src/Tgstation.Server.Host/Components/Watchdog/BasicWatchdog.cs

@@ -163,9 +163,13 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		}
 
 		/// <inheritdoc />
-		protected override void DisposeAndNullControllersImpl()
+		protected override async Task DisposeAndNullControllersImpl()
 		{
-			Server?.Dispose();
+			var disposeTask = Server?.DisposeAsync();
+			if (!disposeTask.HasValue)
+				return;
+
+			await disposeTask.Value.ConfigureAwait(false);
 			Server = null;
 			gracefulRebootRequired = false;
 		}
@@ -227,7 +231,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 			{
 				// kill the controllers
 				bool serverWasActive = Server != null;
-				DisposeAndNullControllers();
+				await DisposeAndNullControllers(default).ConfigureAwait(false);
 
 				// server didn't get control of this dmb
 				if (dmbToUse != null && !serverWasActive)

src/Tgstation.Server.Host/Components/Watchdog/IWatchdog.cs

@@ -12,7 +12,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 	/// <summary>
 	/// Runs and monitors the twin server controllers
 	/// </summary>
-	public interface IWatchdog : IHostedService, IDisposable, IEventConsumer, IRenameNotifyee
+	public interface IWatchdog : IHostedService, IAsyncDisposable, IEventConsumer, IRenameNotifyee
 	{
 		/// <summary>
 		/// The current <see cref="WatchdogStatus"/>.

src/Tgstation.Server.Host/Components/Watchdog/WatchdogBase.cs

@@ -59,11 +59,6 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// </summary>
 		protected TaskCompletionSource<object> ActiveParametersUpdated { get; set; }
 
-		/// <summary>
-		/// The <see cref="SemaphoreSlim"/> for the <see cref="WatchdogBase"/>.
-		/// </summary>
-		protected SemaphoreSlim Semaphore { get; }
-
 		/// <summary>
 		/// The <see cref="ILogger"/> for the <see cref="WatchdogBase"/>.
 		/// </summary>
@@ -94,6 +89,16 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// </summary>
 		readonly Api.Models.Instance instance;
 
+		/// <summary>
+		/// The <see cref="SemaphoreSlim"/> for the <see cref="WatchdogBase"/>.
+		/// </summary>
+		readonly SemaphoreSlim synchronizationSemaphore;
+
+		/// <summary>
+		/// <see cref="SemaphoreSlim"/> used for <see cref="DisposeAndNullControllers"/>.
+		/// </summary>
+		readonly SemaphoreSlim controllerDisposeSemaphore;
+
 		/// <summary>
 		/// The <see cref="ISessionPersistor"/> for the <see cref="WatchdogBase"/>
 		/// </summary>
@@ -124,11 +129,6 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// </summary>
 		readonly IEventConsumer eventConsumer;
 
-		/// <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="LaunchNoLock(bool, bool, bool, ReattachInformation, CancellationToken)"/> in <see cref="StartAsync(CancellationToken)"/>
 		/// </summary>
@@ -165,7 +165,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		bool releaseServers;
 
 		/// <summary>
-		/// If the <see cref="WatchdogBase"/> has been <see cref="Dispose"/>d.
+		/// If the <see cref="WatchdogBase"/> has been <see cref="DisposeAsync"/>'d.
 		/// </summary>
 		bool disposed;
 
@@ -224,16 +224,17 @@ namespace Tgstation.Server.Host.Components.Watchdog
 			ActiveLaunchParameters = initialLaunchParameters;
 			releaseServers = false;
 			ActiveParametersUpdated = new TaskCompletionSource<object>();
-			controllerDisposeLock = new object();
 
 			restartRegistration = serverControl.RegisterForRestart(this);
 			try
 			{
-				Semaphore = new SemaphoreSlim(1);
+				synchronizationSemaphore = new SemaphoreSlim(1);
+				controllerDisposeSemaphore = new SemaphoreSlim(1);
 			}
 			catch
 			{
 				restartRegistration.Dispose();
+				synchronizationSemaphore?.Dispose();
 				throw;
 			}
 
@@ -241,18 +242,19 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		}
 
 		/// <inheritdoc />
-		public void Dispose()
+		public async ValueTask DisposeAsync()
 		{
 			Logger.LogTrace("Disposing...");
-			Semaphore.Dispose();
+			synchronizationSemaphore.Dispose();
 			restartRegistration.Dispose();
-			DisposeAndNullControllers();
+			await DisposeAndNullControllers(default).ConfigureAwait(false);
+			controllerDisposeSemaphore.Dispose();
 			monitorCts?.Dispose();
 			disposed = true;
 		}
 
 		/// <summary>
-		/// Implementation of <see cref="Terminate(bool, CancellationToken)"/>. Does not lock <see cref="Semaphore"/>
+		/// Implementation of <see cref="Terminate(bool, CancellationToken)"/>. Does not lock <see cref="synchronizationSemaphore"/>
 		/// </summary>
 		/// <param name="graceful">If <see langword="true"/> the termination will be delayed until a reboot is detected in the active server's DMAPI and this function will return immediately</param>
 		/// <param name="announce">If <see langword="true"/> the termination will be announced using <see cref="Chat"/></param>
@@ -272,8 +274,6 @@ namespace Tgstation.Server.Host.Components.Watchdog
 
 				await StopMonitor().ConfigureAwait(false);
 
-				DisposeAndNullControllers();
-
 				LastLaunchParameters = null;
 
 				await chatTask.ConfigureAwait(false);
@@ -330,7 +330,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 						var message4 = $"DEFCON 1: Four heartbeats have been missed! {actionTaken}...";
 						Logger.LogWarning(message4);
 						await Chat.SendWatchdogMessage(message4, false, cancellationToken).ConfigureAwait(false);
-						DisposeAndNullControllers();
+						await DisposeAndNullControllers(cancellationToken).ConfigureAwait(false);
 						return shouldShutdown ? MonitorAction.Exit : MonitorAction.Restart;
 					default:
 						Logger.LogError("Invalid heartbeats missed count: {0}", heartbeatsMissed);
@@ -477,7 +477,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		protected async Task ReattachFailure(Task chatTask, CancellationToken cancellationToken)
 		{
 			// we lost the server, just restart entirely
-			DisposeAndNullControllers();
+			await DisposeAndNullControllers(default).ConfigureAwait(false);
 			const string FailReattachMessage = "Unable to properly reattach to server! Restarting watchdog...";
 			Logger.LogWarning(FailReattachMessage);
 
@@ -493,16 +493,19 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// <summary>
 		/// Call <see cref="IDisposable.Dispose"/> and null the fields for all <see cref="ISessionController"/>s.
 		/// </summary>
-		protected abstract void DisposeAndNullControllersImpl();
+		/// <returns>A <see cref="Task"/> representing the running operation.</returns>
+		protected abstract Task DisposeAndNullControllersImpl();
 
 		/// <summary>
 		/// Wrapper for <see cref="DisposeAndNullControllersImpl"/> under a locked context.
 		/// </summary>
-		protected void DisposeAndNullControllers()
+		/// <param name="cancellationToken">The <see cref="CancellationToken"/> for the operation.</param>
+		/// <returns>A <see cref="Task"/> representing the running operation.</returns>
+		protected async Task DisposeAndNullControllers(CancellationToken cancellationToken)
 		{
 			Logger.LogTrace("DisposeAndNullControllers");
-			lock (controllerDisposeLock)
-				DisposeAndNullControllersImpl();
+			using (await SemaphoreSlimContext.Lock(controllerDisposeSemaphore, cancellationToken).ConfigureAwait(false))
+				await DisposeAndNullControllersImpl().ConfigureAwait(false);
 		}
 
 		/// <summary>
@@ -529,14 +532,14 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		private async Task MonitorRestart(CancellationToken cancellationToken)
 		{
 			Logger.LogTrace("Monitor restart!");
-			DisposeAndNullControllers();
+			await DisposeAndNullControllers(cancellationToken).ConfigureAwait(false);
 
 			var chatTask = Task.CompletedTask;
 			for (var retryAttempts = 1; ; ++retryAttempts)
 			{
 				Status = WatchdogStatus.Restoring;
 				Exception launchException;
-				using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+				using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 					try
 					{
 						// use LaunchImplNoLock without announcements or restarting the monitor
@@ -633,7 +636,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 							Logger.LogTrace("Monitor activated");
 
 							// always run HandleMonitorWakeup from the context of the semaphore lock
-							using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+							using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 							{
 								// Set this sooner so chat sends don't hold us up
 								if (activeServerLifetime.IsCompleted)
@@ -736,11 +739,11 @@ namespace Tgstation.Server.Host.Components.Watchdog
 				if (releaseServers)
 				{
 					Logger.LogTrace("Detaching servers...");
-					releasedReattachInformation = GetActiveController().Release();
+					releasedReattachInformation = await GetActiveController().Release().ConfigureAwait(false);
 				}
 			}
 
-			DisposeAndNullControllers();
+			await DisposeAndNullControllers(default).ConfigureAwait(false);
 			Status = WatchdogStatus.Offline;
 
 			Logger.LogTrace("Monitor exiting...");
@@ -758,7 +761,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// <inheritdoc />
 		public async Task ChangeSettings(DreamDaemonLaunchParameters launchParameters, CancellationToken cancellationToken)
 		{
-			using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+			using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 			{
 				bool match = launchParameters.CanApplyWithoutReboot(ActiveLaunchParameters);
 				ActiveLaunchParameters = launchParameters;
@@ -808,7 +811,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// <inheritdoc />
 		public async Task<string> HandleChatCommand(string commandName, string arguments, ChatUser sender, CancellationToken cancellationToken)
 		{
-			using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+			using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 			{
 				if (Status == WatchdogStatus.Offline)
 					return "TGS: Server offline!";
@@ -836,14 +839,14 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		{
 			if (Status != WatchdogStatus.Offline)
 				throw new JobException(ErrorCode.WatchdogRunning);
-			using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+			using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 				await LaunchNoLock(true, true, true, null, cancellationToken).ConfigureAwait(false);
 		}
 
 		/// <inheritdoc />
 		public virtual async Task ResetRebootState(CancellationToken cancellationToken)
 		{
-			using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+			using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 			{
 				if (Status == WatchdogStatus.Offline)
 					return;
@@ -860,7 +863,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 				throw new JobException(ErrorCode.WatchdogNotRunning);
 
 			Logger.LogTrace("Begin Restart. Graceful: {0}", graceful);
-			using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+			using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 			{
 				if (!graceful)
 				{
@@ -912,7 +915,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 			};
 			await jobManager.RegisterOperation(job, async (j, databaseContextFactory, progressFunction, ct) =>
 			{
-				using (await SemaphoreSlimContext.Lock(Semaphore, ct).ConfigureAwait(false))
+				using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, ct).ConfigureAwait(false))
 					await LaunchNoLock(true, true, true, reattachInfo, ct).ConfigureAwait(false);
 			}, cancellationToken).ConfigureAwait(false);
 		}
@@ -942,7 +945,7 @@ namespace Tgstation.Server.Host.Components.Watchdog
 		/// <inheritdoc />
 		public async Task Terminate(bool graceful, CancellationToken cancellationToken)
 		{
-			using (await SemaphoreSlimContext.Lock(Semaphore, cancellationToken).ConfigureAwait(false))
+			using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, cancellationToken).ConfigureAwait(false))
 				await TerminateNoLock(graceful, !releaseServers, cancellationToken).ConfigureAwait(false);
 		}
 

src/Tgstation.Server.Host/Components/Watchdog/WindowsWatchdog.cs

@@ -102,15 +102,15 @@ namespace Tgstation.Server.Host.Components.Watchdog
 			}
 			catch
 			{
-				Dispose();
+				var _ = DisposeAsync();
 				throw;
 			}
 		}
 
 		/// <inheritdoc />
-		protected override void DisposeAndNullControllersImpl()
+		protected override async Task DisposeAndNullControllersImpl()
 		{
-			base.DisposeAndNullControllersImpl();
+			await base.DisposeAndNullControllersImpl().ConfigureAwait(false);
 
 			// If we reach this point, we can guarantee PrepServerForLaunch will be called before starting again.
 			ActiveSwappable = null;

src/Tgstation.Server.Host/System/IProcess.cs

@@ -1,4 +1,5 @@
-using System.Threading;
+using System;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace Tgstation.Server.Host.System
@@ -6,7 +7,7 @@ namespace Tgstation.Server.Host.System
 	/// <summary>
 	/// Abstraction over a <see cref="global::System.Diagnostics.Process"/>
 	/// </summary>
-	interface IProcess : IProcessBase
+	interface IProcess : IProcessBase, IDisposable
 	{
 		/// <summary>
 		/// The <see cref="IProcess"/>' ID

src/Tgstation.Server.Host/System/IProcessBase.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Threading;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace Tgstation.Server.Host.System
@@ -7,7 +6,7 @@ namespace Tgstation.Server.Host.System
 	/// <summary>
 	/// Represents process lifetime
 	/// </summary>
-	interface IProcessBase : IDisposable
+	interface IProcessBase
 	{
 		/// <summary>
 		/// The <see cref="Task{TResult}"/> resulting in the exit code of the process