feat: Implement GetCurrentRtt in the adapter (#1755)

* Make ExtractRtt more suitable for other uses

* Implement GetCurrentRtt

* Add CHANGELOG entry

* Make the standards checks happy

Author: simon-lemay-unity

com.unity.netcode.adapter.utp/CHANGELOG.md

@@ -7,6 +7,7 @@ All notable changes to this package will be documented in this file. The format
 ### Added
 
 - New parameters are available to simulate network conditions (delay, jitter, packet loss) in the editor and in development builds. The parameters are available under the 'Debug Simulator' section of the 'Unity Transport' component, or can be set with the `SetDebugSimulatorParameters` call. (#1745)
+- `GetCurrentRtt` is now properly implemented. (#1755)
 
 ### Changed
 

com.unity.netcode.adapter.utp/Runtime/UnityTransport.cs

@@ -744,7 +744,7 @@ private void ExtractNetworkMetricsForClient(ulong transportClientId)
             ExtractNetworkMetricsFromPipeline(m_UnreliableSequencedFragmentedPipeline, networkConnection);
             ExtractNetworkMetricsFromPipeline(m_ReliableSequencedPipeline, networkConnection);
 
-            var rttValue = ExtractRtt(networkConnection);
+            var rttValue = NetworkManager.IsServer ? 0 : ExtractRtt(networkConnection);
             NetworkMetrics.TrackRttToServer(rttValue);
         }
 
@@ -773,25 +773,23 @@ private void ExtractNetworkMetricsFromPipeline(NetworkPipeline pipeline, Network
 
         private int ExtractRtt(NetworkConnection networkConnection)
         {
-            if (NetworkManager.IsServer)
+            if (m_Driver.GetConnectionState(networkConnection) != NetworkConnection.State.Connected)
             {
                 return 0;
             }
-            else
+
+            m_Driver.GetPipelineBuffers(m_ReliableSequencedPipeline,
+                NetworkPipelineStageCollection.GetStageId(typeof(ReliableSequencedPipelineStage)),
+                networkConnection,
+                out _,
+                out _,
+                out var sharedBuffer);
+
+            unsafe
             {
-                m_Driver.GetPipelineBuffers(m_ReliableSequencedPipeline,
-                    NetworkPipelineStageCollection.GetStageId(typeof(ReliableSequencedPipelineStage)),
-                    networkConnection,
-                    out _,
-                    out _,
-                    out var sharedBuffer);
-
-                unsafe
-                {
-                    var sharedContext = (ReliableUtility.SharedContext*)sharedBuffer.GetUnsafePtr();
+                var sharedContext = (ReliableUtility.SharedContext*)sharedBuffer.GetUnsafePtr();
 
-                    return sharedContext->RttInfo.LastRtt;
-                }
+                return sharedContext->RttInfo.LastRtt;
             }
         }
 
@@ -866,7 +864,22 @@ public override void DisconnectRemoteClient(ulong clientId)
 
         public override ulong GetCurrentRtt(ulong clientId)
         {
-            return 0;
+            // We don't know if this is getting called from inside NGO (which presumably knows to
+            // use the transport client ID) or from a user (which will be using the NGO client ID).
+            // So we just try both cases (ExtractRtt returns 0 for invalid connections).
+
+            if (NetworkManager != null)
+            {
+                var transportId = NetworkManager.ClientIdToTransportId(clientId);
+
+                var rtt = ExtractRtt(ParseClientId(transportId));
+                if (rtt > 0)
+                {
+                    return (ulong)rtt;
+                }
+            }
+
+            return (ulong)ExtractRtt(ParseClientId(clientId));
         }
 
         public override void Initialize(NetworkManager networkManager = null)

com.unity.netcode.adapter.utp/Tests/Runtime/TransportTests.cs

@@ -361,6 +361,34 @@ public IEnumerator SimulatorParametersAreEffective()
 
             yield return null;
         }
+
+        // Check that RTT is reported correctly.
+        [UnityTest]
+        [UnityPlatform(include = new[] { RuntimePlatform.OSXEditor, RuntimePlatform.WindowsEditor, RuntimePlatform.LinuxEditor })]
+        public IEnumerator CurrentRttReportedCorrectly()
+        {
+            const int simulatedRtt = 25;
+
+            InitializeTransport(out m_Server, out m_ServerEvents);
+            InitializeTransport(out m_Client1, out m_Client1Events);
+
+            m_Server.SetDebugSimulatorParameters(simulatedRtt, 0, 0);
+
+            m_Server.StartServer();
+            m_Client1.StartClient();
+
+            yield return WaitForNetworkEvent(NetworkEvent.Connect, m_Client1Events);
+
+            var data = new ArraySegment<byte>(new byte[] { 42 });
+            m_Client1.Send(m_Client1.ServerClientId, data, NetworkDelivery.Reliable);
+
+            yield return WaitForNetworkEvent(NetworkEvent.Data, m_ServerEvents,
+                timeout: MaxNetworkEventWaitTime + (2 * simulatedRtt));
+
+            Assert.GreaterOrEqual(m_Client1.GetCurrentRtt(m_Client1.ServerClientId), simulatedRtt);
+
+            yield return null;
+        }
     }
 }
 #endif