Watcher

src/pdns-dhcp/Kea/KeaDhcpLeaseFileReader.cs

@@ -0,0 +1,6 @@
+namespace pdns_dhcp.Kea;
+
+public class KeaDhcpLeaseFileReader
+{
+	
+}

src/pdns-dhcp/Kea/KeaLeaseWatcher.cs

@@ -1,12 +1,18 @@
+using System.Threading.Channels;
+
 using Microsoft.Extensions.Hosting;
 
 using pdns_dhcp.Options;
 
 namespace pdns_dhcp.Kea;
 
-public abstract class KeaDhcpLeaseWatcher : BackgroundService
+public abstract class KeaDhcpLeaseWatcher : IHostedService
 {
 	private readonly FileSystemWatcher _fsw;
+	private readonly string _leaseFile;
+	private Channel<FileSystemEventArgs>? _eventChannel;
+	private Task? _executeTask;
+	private CancellationTokenSource? _stoppingCts;
 
 	protected KeaDhcpServerOptions Options { get; }
 
@@ -26,31 +32,107 @@ public abstract class KeaDhcpLeaseWatcher : BackgroundService
 			throw new ArgumentException($"{nameof(options.Leases)} must point to a file in an existing path.", nameof(options));
 		}
 
-		_fsw = new(leaseDirectory, leaseFile.ToString());
+		_leaseFile = leaseFile.ToString();
+		_fsw = new(leaseDirectory, _leaseFile);
 		_fsw.Changed += OnLeaseChanged;
-		_fsw.Created += OnLeaseChanged;
-		_fsw.Deleted += OnLeaseChanged;
-		_fsw.Renamed += OnLeaseRenamed;
 		_fsw.Error += OnLeaseError;
 	}
 
-	protected override Task ExecuteAsync(CancellationToken stoppingToken)
+	public Task StartAsync(CancellationToken cancellationToken)
 	{
-		return Task.CompletedTask;
+		_stoppingCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+		_executeTask = Reading(_stoppingCts.Token);
+		return _executeTask is { IsCompleted: true } completed ? completed : Task.CompletedTask;
+	}
+
+	public async Task StopAsync(CancellationToken cancellationToken)
+	{
+		if (_executeTask is null)
+		{
+			return;
+		}
+
+		_fsw.EnableRaisingEvents = false;
+		try
+		{
+			_stoppingCts!.Cancel();
+		}
+		finally
+		{
+			TaskCompletionSource taskCompletionSource = new();
+			using (cancellationToken.Register(s => ((TaskCompletionSource)s!).SetCanceled(), taskCompletionSource))
+			{
+				await Task.WhenAny(_executeTask, taskCompletionSource.Task).ConfigureAwait(continueOnCapturedContext: false);
+			}
+		}
+	}
+
+	private async Task Reading(CancellationToken stoppingToken)
+	{
+		while (!stoppingToken.IsCancellationRequested)
+		{
+			using CancellationTokenSource loopCts = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken);
+			_eventChannel = Channel.CreateUnbounded<FileSystemEventArgs>();
+			_fsw.EnableRaisingEvents = true;
+			ValueTask reader = default;
+			try
+			{
+				await foreach (var @event in _eventChannel.Reader.ReadAllAsync(loopCts.Token))
+				{
+					switch (@event)
+					{
+						case { ChangeType: WatcherChangeTypes.Created }:
+						case RenamedEventArgs { ChangeType: WatcherChangeTypes.Renamed } renamed when renamed.Name == _leaseFile:
+							reader = FileReader(loopCts.Token);
+							break;
+
+						case { ChangeType: WatcherChangeTypes.Deleted }:
+						case RenamedEventArgs { ChangeType: WatcherChangeTypes.Renamed } renamed when renamed.OldName == _leaseFile:
+							loopCts.Cancel();
+							break;
+
+						case { ChangeType: WatcherChangeTypes.Changed }:
+							break;
+					}
+				}
+			}
+			catch { }
+			finally
+			{
+				_eventChannel.Writer.TryComplete();
+				try
+				{
+					await reader.ConfigureAwait(continueOnCapturedContext: false);
+				}
+				catch { }
+			}
+		}
+
+		ValueTask FileReader(CancellationToken stoppingToken)
+		{
+			return ValueTask.CompletedTask;
+		}
 	}
 
 	private void OnLeaseChanged(object sender, FileSystemEventArgs e)
 	{
-		throw new NotImplementedException();
+		var writer = _eventChannel?.Writer;
+		if (writer?.TryWrite(e) != false)
+		{
+			return;
+		}
+
+		var write = writer.WriteAsync(e);
+		if (write.IsCompleted)
+		{
+			return;
+		}
+
+		write.GetAwaiter().GetResult();
 	}
 
 	private void OnLeaseError(object sender, ErrorEventArgs e)
 	{
-		throw new NotImplementedException();
-	}
-
-	private void OnLeaseRenamed(object sender, RenamedEventArgs e)
-	{
-		throw new NotImplementedException();
+		_eventChannel?.Writer.Complete(e.GetException());
 	}
 }