More ManagerState states; track last error relative time

StackExchange.Redis/StackExchange/Redis/ConnectionMultiplexer.cs

@@ -1876,6 +1876,8 @@ internal T ExecuteSyncImpl<T>(Message message, ResultProcessor<T> processor, Ser
                             string iocp, worker;
 #if !__MonoCS__
                             var mgrState = socketManager.State;
+                            var lastError = socketManager.LastErrorTimeRelative();
+
 #endif
                             var sb = new StringBuilder("Timeout performing ").Append(message.CommandAndKey);
                             data = new List<Tuple<string, string>> {Tuple.Create("Message", message.CommandAndKey)};
@@ -1890,6 +1892,7 @@ internal T ExecuteSyncImpl<T>(Message message, ResultProcessor<T> processor, Ser
                             add("Instantaneous", "inst", inst.ToString());
 #if !__MonoCS__
                             add("Manager-State", "mgr", mgrState.ToString());
+                            add("Last-Error", "err", lastError);
 #endif
                             add("Queue-Length", "queue", queue.ToString());
                             add("Queue-Outstanding", "qu", qu.ToString());

StackExchange.Redis/StackExchange/Redis/PhysicalConnection.cs

@@ -218,7 +218,9 @@ public void RecordConnectionFailed(ConnectionFailureType failureType, Exception
                 add("Last-Multiplexer-Heartbeat", "last-mbeat", multiplexer.LastHeartbeatSecondsAgo + "s ago");
                 add("Last-Global-Heartbeat", "global", ConnectionMultiplexer.LastGlobalHeartbeatSecondsAgo + "s ago");
 #if !__MonoCS__
-                add("SocketManager-State", "mgr", bridge.Multiplexer.SocketManager.State.ToString());
+                var mgr = bridge.Multiplexer.SocketManager;
+                add("SocketManager-State", "mgr", mgr.State.ToString());
+                add("Last-Error", "err", mgr.LastErrorTimeRelative());
 #endif
                 
                 var ex = innerException == null

StackExchange.Redis/StackExchange/Redis/SocketManager.Poll.cs

@@ -162,6 +162,8 @@ internal enum ManagerState
             GrowingSocketArray,
             CopyingPointersForSelect,
             ExecuteSelect,
+            ExecuteSelectComplete,
+            CheckForStaleConnections,
             EnqueueRead,
             EnqueueError,
             RequestAssistance,
@@ -174,7 +176,13 @@ internal ManagerState State
             get { return managerState; }
         }
         private volatile ManagerState managerState;
-
+        private volatile int lastErrorTicks;
+        internal string LastErrorTimeRelative()
+        {
+            var tmp = lastErrorTicks;
+            if (tmp == 0) return "never";
+            return unchecked(Environment.TickCount - tmp) + "ms ago";
+        }
         private void ReadImpl()
         {
             List<IntPtr> dead = null, active = new List<IntPtr>();
@@ -268,15 +276,21 @@ private void ReadImpl()
                     var timeout = new TimeValue(1000);
                     managerState = ManagerState.ExecuteSelect;
                     ready = select(0, readSockets, null, errorSockets, ref timeout);
+                    managerState = ManagerState.ExecuteSelectComplete;
                     if (ready <= 0)
                     {
                         if (ready == 0)
                         {
+                            managerState = ManagerState.CheckForStaleConnections;
                             foreach (var s in activeCallbacks)
                             {
                                 s.CheckForStaleConnection();
                             }
                         }
+                        else
+                        {
+                            lastErrorTicks = Environment.TickCount;
+                        }
                         continue; // -ve typically means a socket was disposed just before; just retry
                     }