diff --git a/src/GameCult.Networking/CultNetRudpSchemaServer.cs b/src/GameCult.Networking/CultNetRudpSchemaServer.cs index 444e97e9..3378036a 100644 --- a/src/GameCult.Networking/CultNetRudpSchemaServer.cs +++ b/src/GameCult.Networking/CultNetRudpSchemaServer.cs @@ -126,6 +126,12 @@ namespace GameCult.Networking /// public const int MaxConsecutiveRefusedFrames = 8; + /// + /// How long a session whose capped frame was answered waits for the peer to acknowledge the answer + /// before it ends anyway. + /// + internal const long CappedAnswerGraceMs = 2000; + /// /// Gets or sets the logger used by the server. R-AM: the dispatch backstop in DispatchAsync /// logs every untyped fault through this instead of swallowing it silently. @@ -310,6 +316,9 @@ namespace GameCult.Networking { if (!string.Equals(delivered.Frame.ChannelId, "schema", StringComparison.Ordinal)) return false; + // The capped frame was answered: nothing after it is served while the answer is delivered. + if (delivered.Peer.EndingReason != null) + return false; // A peer's message that cannot be decoded (malformed bytes, an unknown schemaVersion) or // handled ends that peer's session, never the poll: the drain goes on serving every other @@ -337,8 +346,10 @@ namespace GameCult.Networking Logger.LogError($"CultNet RUDP schema server could not decode a peer's message ({ex.GetType().Name}); it was refused and that peer's session kept."); return false; } - var ended = _transport.EndPeerSession(delivered.Peer, CultNetRudpSession.RefusedPacketReason); - Logger.LogError($"CultNet RUDP schema server could not decode a peer's message ({ex.GetType().Name}); {SessionOutcome(ended)}"); + // The answer was sent reliably: the session ends once the peer has acknowledged it (a lost + // datagram is resent first), or after the grace. + _transport.EndPeerSessionWhenAnswered(delivered.Peer, CultNetRudpSession.RefusedPacketReason, CappedAnswerGraceMs); + Logger.LogError($"CultNet RUDP schema server could not decode a peer's message ({ex.GetType().Name}); that peer's session ends once its answer is acknowledged."); return false; } _undecodableFramesInARow.GetOrCreateValue(delivered.Peer).Value = 0; diff --git a/src/GameCult.Networking/CultNetTransport.cs b/src/GameCult.Networking/CultNetTransport.cs index ac2c2952..da465326 100644 --- a/src/GameCult.Networking/CultNetTransport.cs +++ b/src/GameCult.Networking/CultNetTransport.cs @@ -2759,6 +2759,11 @@ namespace GameCult.Networking // under SessionGate by whichever thread's send found the failure; the polling thread reads // it when it retires the peer. internal byte[]? UnsendableReason { get; set; } + + // Set once the peer's capped frame has been answered: the session ends with this reason when the + // peer has acknowledged every answer, or at the deadline. Under SessionGate. + internal byte[]? EndingReason { get; set; } + internal long EndingDeadlineMs { get; set; } } /// @@ -2928,6 +2933,7 @@ namespace GameCult.Networking public bool TryReceiveOnce(out CultNetRudpSocketServerFrame? delivered) { RetireUnsendablePeers(); + EndAnsweredPeers(); if (_deliveredFrames.Count > 0) { delivered = _deliveredFrames.Dequeue(); @@ -3146,6 +3152,7 @@ namespace GameCult.Networking public void PollResends() { RetireUnsendablePeers(); + EndAnsweredPeers(); if (_socket.Poll(0, SelectMode.SelectRead)) return; foreach (var peer in _peers.Values.ToArray()) @@ -3244,6 +3251,44 @@ namespace GameCult.Networking return true; } + // Polling thread only. The application answered a peer's capped frame: the answer is reliable, so a + // lost datagram is resent, and the session ends with `reason` once the peer has acknowledged every + // answer or `graceMs` have passed (EndAnsweredPeers). Frames of the peer still queued are not delivered. + internal void EndPeerSessionWhenAnswered(CultNetRudpSocketServerPeer peer, byte[] reason, long graceMs) + { + if (peer == null) throw new ArgumentNullException(nameof(peer)); + if (reason == null) throw new ArgumentNullException(nameof(reason)); + lock (peer.SessionGate) + { + if (peer.Session.Ended || peer.EndingReason != null) + return; + peer.EndingReason = reason; + peer.EndingDeadlineMs = NowMs() + graceMs; + } + var kept = _deliveredFrames.Where(frame => !ReferenceEquals(frame.Peer, peer)).ToArray(); + _deliveredFrames.Clear(); + foreach (var frame in kept) + _deliveredFrames.Enqueue(frame); + } + + // Polling thread only. + private void EndAnsweredPeers() + { + foreach (var peer in _peers.Values.ToArray()) + { + byte[]? reason; + lock (peer.SessionGate) + { + reason = peer.EndingReason != null + && (peer.Session.OutstandingReliablePacketCount == 0 || NowMs() >= peer.EndingDeadlineMs) + ? peer.EndingReason + : null; + } + if (reason != null) + EndPeerSession(peer, reason); + } + } + // Polling thread only. A peer a new Connect already replaced was reported then, and its key now // names the peer that replaced it. private void RetireUnsendablePeers() diff --git a/tests/GameCult.Networking.Tests/CultNetRudpSchemaServerPeerInputTests.cs b/tests/GameCult.Networking.Tests/CultNetRudpSchemaServerPeerInputTests.cs index a07b1771..e7900e7c 100644 --- a/tests/GameCult.Networking.Tests/CultNetRudpSchemaServerPeerInputTests.cs +++ b/tests/GameCult.Networking.Tests/CultNetRudpSchemaServerPeerInputTests.cs @@ -191,6 +191,95 @@ namespace GameCult.Networking.Tests return errors; } + // The bad peer acknowledges what it received and the server polls on. + private static async Task Acknowledge(Scene scene) + { + scene.Bad.Socket.SendTo(CultNetRudpPacketCodec.Encode(scene.Bad.Session.CreateAck()), scene.Server.LocalEndPoint); + await scene.Server.PollAvailableAsync(16); + } + + // The bad peer has sent seven undecodable frames (BadThenGood sent the first), each answered. + private static async Task AtTheCap() + { + var scene = await BadThenGood(Malformed()); + await scene.Server.PollAvailableAsync(16); + ErrorsReceivedBy(scene.Bad); + for (var i = 0; i < 6; i++) + { + SendSchema(scene.Server, scene.Bad, Malformed()); + await scene.Server.PollAvailableAsync(16); + ErrorsReceivedBy(scene.Bad); + } + Assert.That(scene.Ended, Is.Empty); + return scene; + } + + // The capped frame's answer is lost on the wire: the server resends it, and the goodbye follows only + // once the peer has acknowledged it. + [Test] + public async Task ALostCappedAnswerIsResentAndTheGoodbyeWaitsForItsAcknowledgement() + { + using var scene = await AtTheCap(); + SendSchema(scene.Server, scene.Bad, Malformed()); + await scene.Server.PollAvailableAsync(16); + + var lost = Drain(scene.Bad.Socket); + Assert.That(lost.Where(p => p.PacketType == CultNetRudpPacketType.Data), Is.Not.Empty, "fixture: the answer was sent and is lost here"); + Assert.That(lost.Select(p => p.PacketType), Has.None.EqualTo(CultNetRudpPacketType.Disconnect), "no goodbye before the answer is acknowledged"); + Assert.That(scene.Ended, Is.Empty); + + var resent = new List(); + for (var attempt = 0; attempt < 40 && resent.Count == 0; attempt++) + { + await Task.Delay(50); + scene.Server.PollResends(); + resent = Drain(scene.Bad.Socket); + } + Assert.That(resent.Select(p => p.PacketType), Has.None.EqualTo(CultNetRudpPacketType.Disconnect), "still no goodbye"); + var answers = new List(); + foreach (var packet in resent) + foreach (var frame in scene.Bad.Session.Receive(packet, 1).Delivered) + if (CultNetSchemaMessageSerialization.Deserialize(frame.Payload) is CultNetErrorMessage error) + answers.Add(error); + Assert.That(answers.Select(e => e.Code), Is.EqualTo(new[] { "message_invalid" }), "the lost answer arrived by resend"); + Assert.That(scene.Ended, Is.Empty); + + await Acknowledge(scene); + Assert.That(scene.Ended, Is.EqualTo(new[] { scene.Bad.EndPoint }), "acknowledged: the session ends"); + Assert.That(Drain(scene.Bad.Socket).Select(p => p.PacketType), Has.Some.EqualTo(CultNetRudpPacketType.Disconnect)); + } + + // A peer that never acknowledges the answer is not kept for ever: the session ends after the grace. + [Test] + public async Task ACappedSessionWhoseAnswerIsNeverAcknowledgedEndsAfterTheGrace() + { + using var scene = await AtTheCap(); + SendSchema(scene.Server, scene.Bad, Malformed()); + await scene.Server.PollAvailableAsync(16); + Drain(scene.Bad.Socket); + + await Task.Delay(1500); // the grace is two seconds + scene.Server.PollResends(); + Assert.That(scene.Ended, Is.Empty, "inside the grace"); + await Task.Delay(700); + scene.Server.PollResends(); + Assert.That(scene.Ended, Is.EqualTo(new[] { scene.Bad.EndPoint }), "the grace ran out"); + } + + // Nothing behind the capped frame is served while its answer is delivered. + [Test] + public async Task NothingBehindTheCappedFrameIsServed() + { + using var scene = await AtTheCap(); + SendSchema(scene.Server, scene.Bad, Malformed()); + SendSchema(scene.Server, scene.Bad, CultNetSchemaMessageSerialization.Serialize( + new CultNetShardCatalogRequestMessage { MessageId = "behind-the-cap" })); + await scene.Server.PollAvailableAsync(16); + await scene.Server.PollAvailableAsync(16); + + Assert.That(scene.Served.Select(s => s.MessageId), Does.Not.Contain("behind-the-cap")); + } + // The numbers are the shared cross-runtime cap, spelled out so changing the constant fails here. [Test] public async Task EightConsecutiveUndecodableFramesEndTheSessionAfterTheEighthIsAnswered() @@ -221,6 +310,8 @@ namespace GameCult.Networking.Tests await Refuse(1); Assert.That(ErrorsReceivedBy(scene.Bad).Select(e => e.Code), Is.EqualTo(new[] { "message_invalid" }), "the eighth is answered too"); + Assert.That(scene.Ended, Is.Empty, "the session ends once the answer is acknowledged"); + await Acknowledge(scene); Assert.That(scene.Ended, Is.EqualTo(new[] { scene.Bad.EndPoint })); Assert.That(scene.Server.Peers.Select(peer => peer.RemoteEndPoint), Is.EqualTo(new[] { scene.Good.EndPoint })); }