Agent/Phantom.Agent.Minecraft/Java/JvmArgumentBuilder.cs

@@ -1,4 +1,5 @@
-using System.Collections.ObjectModel;
+using System.Collections.Immutable;
+using System.Collections.ObjectModel;
 
 namespace Phantom.Agent.Minecraft.Java;
 
@@ -6,12 +7,12 @@ sealed class JvmArgumentBuilder {
 	private readonly JvmProperties basicProperties;
 	private readonly List<string> customArguments = new ();
 
-	public JvmArgumentBuilder(JvmProperties basicProperties) {
+	public JvmArgumentBuilder(JvmProperties basicProperties, ImmutableArray<string> customArguments) {
 		this.basicProperties = basicProperties;
-	}
 
-	public void Add(string argument) {
-		customArguments.Add(argument);
+		foreach (var jvmArgument in customArguments) {
+			this.customArguments.Add(jvmArgument);
+		}
 	}
 
 	public void AddProperty(string key, string value) {
@@ -23,8 +24,8 @@ sealed class JvmArgumentBuilder {
 			target.Add(property);
 		}
 
-		// In case of duplicate JVM arguments, typically the last one wins.
 		target.Add("-Xms" + basicProperties.InitialHeapMegabytes + "M");
 		target.Add("-Xmx" + basicProperties.MaximumHeapMegabytes + "M");
+		target.Add("-Xrs");
 	}
 }

Agent/Phantom.Agent.Minecraft/Launcher/BaseLauncher.cs

@@ -2,6 +2,7 @@
 using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Server;
+using Phantom.Common.Data.Java;
 using Phantom.Utils.Runtime;
 using Serilog;
 
@@ -21,6 +22,10 @@ public abstract class BaseLauncher : IServerLauncher {
 			return new LaunchResult.InvalidJavaRuntime();
 		}
 
+		if (JvmArgumentsHelper.Validate(instanceProperties.JvmArguments) != null) {
+			return new LaunchResult.InvalidJvmArguments();
+		}
+
 		var vanillaServerJarPath = await services.ServerExecutables.DownloadAndGetPath(instanceProperties.LaunchProperties.ServerDownloadInfo, MinecraftVersion, downloadProgressEventHandler, cancellationToken);
 		if (vanillaServerJarPath == null) {
 			return new LaunchResult.CouldNotDownloadMinecraftServer();
@@ -56,8 +61,16 @@ public abstract class BaseLauncher : IServerLauncher {
 			UseShellExecute = false
 		};
 		
+		var jvmArguments = new JvmArgumentBuilder(instanceProperties.JvmProperties, instanceProperties.JvmArguments);
+		CustomizeJvmArguments(jvmArguments);
+
 		var processArguments = processConfigurator.ArgumentList;
-		PrepareJvmArguments(serverJar).Build(processArguments);
+		jvmArguments.Build(processArguments);
+		
+		foreach (var extraArgument in serverJar.ExtraArgs) {
+			processArguments.Add(extraArgument);
+		}
+		
 		processArguments.Add("-jar");
 		processArguments.Add(serverJar.FilePath);
 		processArguments.Add("nogui");
@@ -82,21 +95,6 @@ public abstract class BaseLauncher : IServerLauncher {
 		return new LaunchResult.Success(instanceProcess);
 	}
 
-	private JvmArgumentBuilder PrepareJvmArguments(ServerJarInfo serverJar) {
-		var builder = new JvmArgumentBuilder(instanceProperties.JvmProperties);
-
-		foreach (string argument in instanceProperties.JvmArguments) {
-			builder.Add(argument);
-		}
-
-		foreach (var argument in serverJar.ExtraArgs) {
-			builder.Add(argument);
-		}
-
-		CustomizeJvmArguments(builder);
-		return builder;
-	}
-
 	private protected virtual void CustomizeJvmArguments(JvmArgumentBuilder arguments) {}
 
 	private protected virtual Task<ServerJarInfo> PrepareServerJar(ILogger logger, string serverJarPath, CancellationToken cancellationToken) {

Agent/Phantom.Agent.Minecraft/Launcher/LaunchResult.cs

@@ -9,6 +9,8 @@ public abstract record LaunchResult {
 
 	public sealed record InvalidJavaRuntime : LaunchResult;
 	
+	public sealed record InvalidJvmArguments : LaunchResult;
+
 	public sealed record CouldNotDownloadMinecraftServer : LaunchResult;
 	
 	public sealed record CouldNotPrepareMinecraftServerLauncher : LaunchResult;

Agent/Phantom.Agent.Services/Instances/Procedures/LaunchInstanceProcedure.cs

@@ -63,6 +63,9 @@ sealed record LaunchInstanceProcedure(InstanceConfiguration Configuration, IServ
 		if (launchResult is LaunchResult.InvalidJavaRuntime) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.JavaRuntimeNotFound, "Session failed to launch, invalid Java runtime.");
 		}
+		else if (launchResult is LaunchResult.InvalidJvmArguments) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.InvalidJvmArguments, "Session failed to launch, invalid JVM arguments.");
+		}
 		else if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotDownloadMinecraftServer, "Session failed to launch, could not download Minecraft server.");
 		}

Common/Phantom.Common.Data/Instance/InstanceLaunchFailReason.cs

@@ -1,16 +1,17 @@
 namespace Phantom.Common.Data.Instance;
 
 public enum InstanceLaunchFailReason : byte {
-	UnknownError                           = 0,
-	ServerPortNotAllowed                   = 1,
-	ServerPortAlreadyInUse                 = 2,
-	RconPortNotAllowed                     = 3,
-	RconPortAlreadyInUse                   = 4,
-	JavaRuntimeNotFound                    = 5,
-	CouldNotDownloadMinecraftServer        = 6,
-	CouldNotConfigureMinecraftServer       = 7,
-	CouldNotPrepareMinecraftServerLauncher = 8,
-	CouldNotStartMinecraftServer           = 9
+	UnknownError,
+	ServerPortNotAllowed,
+	ServerPortAlreadyInUse,
+	RconPortNotAllowed,
+	RconPortAlreadyInUse,
+	JavaRuntimeNotFound,
+	InvalidJvmArguments,
+	CouldNotDownloadMinecraftServer,
+	CouldNotConfigureMinecraftServer,
+	CouldNotPrepareMinecraftServerLauncher,
+	CouldNotStartMinecraftServer
 }
 
 public static class InstanceLaunchFailReasonExtensions {
@@ -21,6 +22,7 @@ public static class InstanceLaunchFailReasonExtensions {
 			InstanceLaunchFailReason.RconPortNotAllowed                     => "Rcon port not allowed.",
 			InstanceLaunchFailReason.RconPortAlreadyInUse                   => "Rcon port already in use.",
 			InstanceLaunchFailReason.JavaRuntimeNotFound                    => "Java runtime not found.",
+			InstanceLaunchFailReason.InvalidJvmArguments                    => "Invalid JVM arguments.",
 			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer        => "Could not download Minecraft server.",
 			InstanceLaunchFailReason.CouldNotConfigureMinecraftServer       => "Could not configure Minecraft server.",
 			InstanceLaunchFailReason.CouldNotPrepareMinecraftServerLauncher => "Could not prepare Minecraft server launcher.",

Common/Phantom.Common.Data/Java/JvmArgumentsHelper.cs

@@ -1,21 +1,17 @@
 using System.Collections.Immutable;
 
-namespace Phantom.Server.Minecraft;
+namespace Phantom.Common.Data.Java;
 
 public static class JvmArgumentsHelper {
 	public static ImmutableArray<string> Split(string arguments) {
 		return arguments.Split('\n', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries).ToImmutableArray();
 	}
 
-	public static string Join(ImmutableArray<string> arguments) {
-		return string.Join('\n', arguments);
-	}
-
 	public static ValidationError? Validate(string arguments) {
 		return Validate(Split(arguments));
 	}
 	
-	private static ValidationError? Validate(ImmutableArray<string> arguments) {
+	public static ValidationError? Validate(ImmutableArray<string> arguments) {
 		if (!arguments.All(static argument => argument.StartsWith('-'))) {
 			return ValidationError.InvalidFormat;
 		}
@@ -32,6 +28,10 @@ public static class JvmArgumentsHelper {
 		return null;
 	}
 
+	public static string Join(ImmutableArray<string> arguments) {
+		return string.Join('\n', arguments);
+	}
+
 	public enum ValidationError {
 		InvalidFormat,
 		XmxNotAllowed,