Add adaptive packet loss handling

tests/VoiceCat.Tests/MediaRelayTests.cs

@@ -10,6 +10,34 @@ namespace VoiceCat.Tests;
 
 public sealed class MediaRelayTests
 {
+    [Fact]
+    public async Task AutomaticModeReportsAuthenticatedSenderUplinkLossWithCap()
+    {
+        var clock = new ManualClock();
+        await using var fixture = new ServerFixture(timeProvider: clock);
+        Client admin = await ChannelManagementTests.AdminAsync(fixture);
+        using (var store = new VoiceCat.Server.Data.AccountStore(Path.Combine(fixture.Directory, "voicecat.db")))
+        {
+            Channel lobby = store.LoadChannels().Single(channel => channel.Id == 1);
+            lobby.Audio.PacketLossMode = PacketLossMode.PacketLossAutoFast;
+            Assert.True(await ChannelManagementTests.ResultAsync(admin, new() { EditChannel = new() { Channel = lobby } }));
+        }
+        await using var alice = await VoicePeer.AttachAsync(fixture, admin);
+        await using var bob = await VoicePeer.ConnectAsync(fixture, "Bob");
+        StreamAnnounceResult stream = await alice.AnnounceAsync(StreamKind.StreamMic);
+
+        await alice.SendAsync(alice.Seal(stream.Ssrc, [1]));
+        await bob.ReceiveVoiceAsync();
+        for (int i = 0; i < 99; i++) alice.Seal(stream.Ssrc, [2]);
+        clock.Advance(TimeSpan.FromSeconds(3));
+        await alice.SendAsync(alice.Seal(stream.Ssrc, [3]));
+
+        PacketLossUpdate update = (await admin.ReadUntilAsync(envelope => envelope.PacketLossUpdate is not null)).PacketLossUpdate;
+        Assert.Equal(1U, update.ChannelId);
+        Assert.Equal(99U, update.MeasuredPercent);
+        Assert.Equal(30U, update.AppliedPercent);
+    }
+
     [Fact]
     public async Task DisconnectInvalidatesBothBindingAndActiveStreams()
     {
@@ -162,6 +190,10 @@ public sealed class MediaRelayTests
         {
             Client client = await fixture.ConnectAsync();
             await client.LoginAsync(nickname);
+            return await AttachAsync(fixture, client);
+        }
+        internal static async Task<VoicePeer> AttachAsync(ServerFixture fixture, Client client)
+        {
             var peer = new VoicePeer(client, fixture.Server.MediaEndPoint, await client.TakeMediaCryptoAsync());
             client.Send(new() { UdpBinding = new() { UdpToken = client.Authentication!.UdpToken } });
             Assert.True((await client.ReadUntilAsync(e => e.UdpBinding is not null)).UdpBinding.Ack);
@@ -217,4 +249,12 @@ public sealed class MediaRelayTests
         }
         public async ValueTask DisposeAsync() { udp.Dispose(); crypto.Dispose(); await Client.DisposeAsync(); }
     }
+
+    private sealed class ManualClock : TimeProvider
+    {
+        private long timestamp;
+        public override long TimestampFrequency => 1_000;
+        public override long GetTimestamp() => Volatile.Read(ref timestamp);
+        internal void Advance(TimeSpan duration) => Interlocked.Add(ref timestamp, (long)duration.TotalMilliseconds);
+    }
 }