Make writing server.properties file asynchronous

Agent/Phantom.Agent.Minecraft/Java/JavaPropertiesFileEditor.cs

@@ -0,0 +1,92 @@
+using System.Text;
+using Kajabity.Tools.Java;
+
+namespace Phantom.Agent.Minecraft.Java;
+
+sealed class JavaPropertiesFileEditor {
+	private static readonly Encoding Encoding = Encoding.GetEncoding("ISO-8859-1");
+
+	private readonly Dictionary<string, string> overriddenProperties = new ();
+
+	public void Set(string key, string value) {
+		overriddenProperties[key] = value;
+	}
+
+	public async Task EditOrCreate(string filePath) {
+		if (File.Exists(filePath)) {
+			string tmpFilePath = filePath + ".tmp";
+			File.Copy(filePath, tmpFilePath, overwrite: true);
+			await EditFromCopyOrCreate(filePath, tmpFilePath);
+			File.Move(tmpFilePath, filePath, overwrite: true);
+		}
+		else {
+			await EditFromCopyOrCreate(null, filePath);
+		}
+	}
+
+	private async Task EditFromCopyOrCreate(string? sourceFilePath, string targetFilePath) {
+		var properties = new JavaProperties();
+
+		if (sourceFilePath != null) {
+			// TODO replace with custom async parser
+			await using var sourceStream = new FileStream(sourceFilePath, FileMode.Open, FileAccess.Read, FileShare.Read);
+			properties.Load(sourceStream, Encoding);
+		}
+
+		foreach (var (key, value) in overriddenProperties) {
+			properties[key] = value;
+		}
+
+		await using var targetStream = new FileStream(targetFilePath, FileMode.Create, FileAccess.Write, FileShare.Read);
+		await using var targetWriter = new StreamWriter(targetStream, Encoding);
+
+		await targetWriter.WriteLineAsync("# Properties");
+
+		foreach (var (key, value) in properties) {
+			await WriteProperty(targetWriter, key, value);
+		}
+	}
+
+	private static async Task WriteProperty(StreamWriter writer, string key, string value) {
+		await WritePropertyComponent(writer, key, escapeSpaces: true);
+		await writer.WriteAsync('=');
+		await WritePropertyComponent(writer, value, escapeSpaces: false);
+		await writer.WriteLineAsync();
+	}
+
+	private static async Task WritePropertyComponent(TextWriter writer, string component, bool escapeSpaces) {
+		for (int index = 0; index < component.Length; index++) {
+			var c = component[index];
+			switch (c) {
+				case '\\':
+				case '#':
+				case '!':
+				case '=':
+				case ':':
+				case ' ' when escapeSpaces || index == 0:
+					await writer.WriteAsync('\\');
+					await writer.WriteAsync(c);
+					break;
+				case var _ when c > 31 && c < 127:
+					await writer.WriteAsync(c);
+					break;
+				case '\t':
+					await writer.WriteAsync("\\t");
+					break;
+				case '\n':
+					await writer.WriteAsync("\\n");
+					break;
+				case '\r':
+					await writer.WriteAsync("\\r");
+					break;
+				case '\f':
+					await writer.WriteAsync("\\f");
+					break;
+				default:
+					await writer.WriteAsync("\\u");
+					await writer.WriteAsync(((int) c).ToString("X4"));
+					break;
+			}
+		}
+	}
+}

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

@@ -1,5 +1,4 @@
 using System.Text;
-using Kajabity.Tools.Java;
 using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Server;
@@ -108,21 +107,8 @@ public abstract class BaseLauncher : IServerLauncher {
 	}
 
 	private static async Task UpdateServerProperties(InstanceProperties instanceProperties) {
-		var serverPropertiesFilePath = Path.Combine(instanceProperties.InstanceFolder, "server.properties");
+		var serverPropertiesEditor = new JavaPropertiesFileEditor();
-		var serverPropertiesData = new JavaProperties();
+		instanceProperties.ServerProperties.SetTo(serverPropertiesEditor);
-
+		await serverPropertiesEditor.EditOrCreate(Path.Combine(instanceProperties.InstanceFolder, "server.properties"));
-		await using var fileStream = new FileStream(serverPropertiesFilePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
-		try {
-			serverPropertiesData.Load(fileStream);
-		} catch (ParseException e) {
-			throw new Exception("Could not parse server.properties file: " + serverPropertiesFilePath, e);
-		}
-		
-		instanceProperties.ServerProperties.SetTo(serverPropertiesData);
-
-		fileStream.Seek(0L, SeekOrigin.Begin);
-		fileStream.SetLength(0L);
-		
-		serverPropertiesData.Store(fileStream, true);
 	}
 }

Agent/Phantom.Agent.Minecraft/Properties/MinecraftServerProperty.cs

@@ -1,4 +1,4 @@
-using Kajabity.Tools.Java;
+using Phantom.Agent.Minecraft.Java;
 
 namespace Phantom.Agent.Minecraft.Properties; 
 
@@ -12,7 +12,7 @@ abstract class MinecraftServerProperty<T> {
 	protected abstract T Read(string value);
 	protected abstract string Write(T value);
 
-	public void Set(JavaProperties properties, T value) {
+	public void Set(JavaPropertiesFileEditor properties, T value) {
-		properties.SetProperty(key, Write(value));
+		properties.Set(key, Write(value));
 	}
 }

Agent/Phantom.Agent.Minecraft/Properties/ServerProperties.cs

@@ -1,4 +1,4 @@
-using Kajabity.Tools.Java;
+using Phantom.Agent.Minecraft.Java;
 
 namespace Phantom.Agent.Minecraft.Properties;
 
@@ -7,7 +7,7 @@ public sealed record ServerProperties(
 	ushort RconPort,
 	bool EnableRcon = true
 ) {
-	internal void SetTo(JavaProperties properties) {
+	internal void SetTo(JavaPropertiesFileEditor properties) {
 		MinecraftServerProperties.ServerPort.Set(properties, ServerPort);
 		MinecraftServerProperties.RconPort.Set(properties, RconPort);
 		MinecraftServerProperties.EnableRcon.Set(properties, EnableRcon);