Add configurable media-aware managed session reaping

dotnet/src/VoiceCat.Server/Transport/MediaRelay.cs

@@ -7,10 +7,11 @@ using VoiceCat.Protocol;
 
 namespace VoiceCat.Server.Transport;
 
-internal sealed class MediaPeer(byte[] token, MediaSessionCrypto crypto)
+internal sealed class MediaPeer(byte[] token, MediaSessionCrypto crypto, SessionActivity? activity = null)
 {
     public byte[] Token { get; } = token;
     public MediaSessionCrypto Crypto { get; } = crypto;
+    public SessionActivity Activity { get; } = activity ?? new(TimeProvider.System);
     // Only the UDP loop reads or changes the endpoint and binding state.
     public SocketAddress? Endpoint { get; set; }
     public void Dispose() { Crypto.Dispose(); CryptographicOperations.ZeroMemory(Token); }
@@ -101,10 +102,15 @@ internal sealed class MediaRelay : IAsyncDisposable
                 if (source is null) continue;
                 if (header.Type == MediaFrameType.Keepalive)
                 {
-                    if (length == VoiceFrameHeader.Size) await SendAsync(input.AsMemory(0, length), sender).ConfigureAwait(false);
+                    if (length == VoiceFrameHeader.Size)
+                    {
+                        source.Peer.Activity.Touch();
+                        await SendAsync(input.AsMemory(0, length), sender).ConfigureAwait(false);
+                    }
                     continue;
                 }
                 if (!fanout.TryStart(input.AsSpan(0, length), source, current)) continue;
+                source.Peer.Activity.Touch();
                 while (fanout.TryNext(out ReadOnlyMemory<byte> packet, out SocketAddress? endpoint))
                     await SendAsync(packet, endpoint!).ConfigureAwait(false);
             }