perf: adding check for no connections (#2130)

* adding check for no connections

Dont need to run Server Update if there are no connections

* adding toggle to disable skip

* formatt

* removing skipUpdateIfNoConnections check, and merging if checks

* removing extra line

* adding tests for NoConnections

Assets/Mirror/Runtime/NetworkServer.cs

@@ -482,13 +482,23 @@ public static void DisconnectAllConnections()
             connections.Clear();
         }
 
+        /// <summary>
+        /// If connections is empty or if only has host
+        /// </summary>
+        /// <returns></returns>
+        public static bool NoConnections()
+        {
+            return connections.Count == 0 || (connections.Count == 1 && localConnection != null);
+        }
+
         /// <summary>
         /// Called from NetworkManager in LateUpdate
         /// <para>The user should never need to pump the update loop manually</para>
         /// </summary>
         public static void Update()
         {
-            if (!active)
+            // dont need to update server if not active or no client connections
+            if (!active || NoConnections())
                 return;
 
             // Check for dead clients but exclude the host client because it

Assets/Mirror/Tests/Editor/NetworkServerTest.cs

@@ -1157,5 +1157,61 @@ public void SendCalledWhileNotActive_ShouldGiveWarning(string functionName)
                     break;
             }
         }
+
+
+        [Test]
+        public void NoConnectionsTest_WithNoConnection()
+        {
+            Assert.That(NetworkServer.NoConnections(), Is.True);
+            Assert.That(NetworkServer.connections.Count, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void NoConnectionsTest_WithConnections()
+        {
+            NetworkServer.connections.Add(1, null);
+            NetworkServer.connections.Add(2, null);
+            Assert.That(NetworkServer.NoConnections(), Is.False);
+            Assert.That(NetworkServer.connections.Count, Is.EqualTo(2));
+
+            NetworkServer.connections.Clear();
+        }
+
+        [Test]
+        public void NoConnectionsTest_WithHostOnly()
+        {
+            ULocalConnectionToServer connectionToServer = new ULocalConnectionToServer();
+            ULocalConnectionToClient connectionToClient = new ULocalConnectionToClient();
+            connectionToServer.connectionToClient = connectionToClient;
+            connectionToClient.connectionToServer = connectionToServer;
+
+            NetworkServer.SetLocalConnection(connectionToClient);
+            NetworkServer.connections.Add(0, connectionToClient);
+
+            Assert.That(NetworkServer.NoConnections(), Is.True);
+            Assert.That(NetworkServer.connections.Count, Is.EqualTo(1));
+
+            NetworkServer.connections.Clear();
+            NetworkServer.RemoveLocalConnection();
+        }
+
+        [Test]
+        public void NoConnectionsTest_WithHostAndConnection()
+        {
+            ULocalConnectionToServer connectionToServer = new ULocalConnectionToServer();
+            ULocalConnectionToClient connectionToClient = new ULocalConnectionToClient();
+            connectionToServer.connectionToClient = connectionToClient;
+            connectionToClient.connectionToServer = connectionToServer;
+
+            NetworkServer.SetLocalConnection(connectionToClient);
+            NetworkServer.connections.Add(0, connectionToClient);
+            NetworkServer.connections.Add(1, null);
+
+            Assert.That(NetworkServer.NoConnections(), Is.False);
+            Assert.That(NetworkServer.connections.Count, Is.EqualTo(2));
+
+            NetworkServer.connections.Clear();
+            NetworkServer.RemoveLocalConnection();
+        }
     }
 }