SignalR: Benchmark server logging

src/SignalR/perf/benchmarkapps/BenchmarkServer/Hubs/EchoHub.cs

@@ -10,6 +10,13 @@ namespace BenchmarkServer.Hubs
 {
     public class EchoHub : Hub
     {
+        private EchoHubConnectionCounter _counter;
+
+        public EchoHub(EchoHubConnectionCounter counter)
+        {
+            _counter = counter;
+        }
+
         public async Task Broadcast(int duration)
         {
             var sent = 0;
@@ -30,6 +37,17 @@ public async Task Broadcast(int duration)
             Console.WriteLine("Broadcast exited: Sent {0} messages", sent);
         }
 
+        public override Task OnConnectedAsync()
+        {
+            _counter?.Connected();
+            return Task.CompletedTask;
+        }
+
+        public override Task OnDisconnectedAsync(Exception exception) {
+            _counter?.Disconnected();
+            return Task.CompletedTask;
+        }
+
         public DateTime Echo(DateTime time)
         {
             return time;

src/SignalR/perf/benchmarkapps/BenchmarkServer/Hubs/EchoHubConnectionCounter.cs

@@ -0,0 +1,53 @@
+using System;
+
+public class EchoHubConnectionCounter
+{
+    private int _connectionCount;
+    private int _peakConnectionCount;
+
+    private readonly object _lock = new object();
+
+    private DateTime _start = DateTime.Now;
+
+    public string Status
+    {
+        get
+        {
+            lock (_lock)
+            {
+                return $"{_connectionCount} current, {_peakConnectionCount} peak.";
+            }
+        }
+    }
+
+    private void LogConnections(string label)
+    {
+        int connectionCount;
+        lock (_lock)
+        {
+            connectionCount = _connectionCount;
+        }
+        if (connectionCount < 100 || connectionCount % 100 == 0)
+        {
+            var timeSinceServerStart = DateTime.Now.Subtract(_start).ToString(@"hh\:mm\:ss");
+            Console.WriteLine($"[{timeSinceServerStart}] {label}: {Status}");
+        }
+    }
+
+    public void Connected()
+    {
+        lock (_lock)
+        {
+            _connectionCount++;
+            _peakConnectionCount = Math.Max(_connectionCount, _peakConnectionCount);
+        }
+        LogConnections("Connected");
+    }
+
+    public void Disconnected() {
+        lock (_lock) {
+            _connectionCount--;
+        }
+        LogConnections("Disconnected");
+    }
+}

src/SignalR/perf/benchmarkapps/BenchmarkServer/Startup.cs

@@ -31,6 +31,8 @@ public void ConfigureServices(IServiceCollection services)
             {
                 signalrBuilder.AddStackExchangeRedis(redisConnectionString);
             }
+
+            services.AddSingleton<EchoHubConnectionCounter>();
         }
 
         public void Configure(IApplicationBuilder app, IHostingEnvironment env)