Fix CSHARP-454. Ping and VerifyState now open a new connection instead of using one from the connection pool, so they work quickly even if the connection pool is oversubscribed.

Author: Robert Stam

Driver/Core/MongoServerInstance.cs

@@ -219,15 +219,15 @@ public IPEndPoint GetIPEndPoint()
         /// </summary>
         public void Ping()
         {
-            var connection = _connectionPool.AcquireConnection(null);
+            // use a new connection instead of one from the connection pool
+            var connection = new MongoConnection(this);
             try
             {
-                var pingCommand = new CommandDocument("ping", 1);
-                connection.RunCommand("admin.$cmd", QueryFlags.SlaveOk, pingCommand, true);
+                Ping(connection);
             }
             finally
             {
-                _connectionPool.ReleaseConnection(connection);
+                connection.Close();
             }
         }
 
@@ -238,21 +238,22 @@ public void VerifyState()
         {
             lock (_serverInstanceLock)
             {
-                // Console.WriteLine("MongoServerInstance[{0}]: VerifyState called.", sequentialId);
-                // if ping fails assume all connections in the connection pool are doomed
+                // use a new connection instead of one from the connection pool
+                var connection = new MongoConnection(this);
                 try
                 {
-                    Ping();
-                }
-                catch
-                {
-                    // Console.WriteLine("MongoServerInstance[{0}]: Ping failed: {1}.", sequentialId, ex.Message);
-                    _connectionPool.Clear();
-                }
+                    // Console.WriteLine("MongoServerInstance[{0}]: VerifyState called.", sequentialId);
+                    // if ping fails assume all connections in the connection pool are doomed
+                    try
+                    {
+                        Ping(connection);
+                    }
+                    catch
+                    {
+                        // Console.WriteLine("MongoServerInstance[{0}]: Ping failed: {1}.", sequentialId, ex.Message);
+                        _connectionPool.Clear();
+                    }
 
-                var connection = _connectionPool.AcquireConnection(null);
-                try
-                {
                     var previousState = _state;
                     try
                     {
@@ -270,7 +271,7 @@ public void VerifyState()
                 }
                 finally
                 {
-                    _connectionPool.ReleaseConnection(connection);
+                    connection.Close();
                 }
             }
         }
@@ -373,6 +374,12 @@ internal void Disconnect()
             }
         }
 
+        internal void Ping(MongoConnection connection)
+        {
+            var pingCommand = new CommandDocument("ping", 1);
+            connection.RunCommand("admin.$cmd", QueryFlags.SlaveOk, pingCommand, true);
+        }
+
         internal void ReleaseConnection(MongoConnection connection)
         {
             _connectionPool.ReleaseConnection(connection);

Driver/Internal/MongoConnection.cs

@@ -74,6 +74,13 @@ internal MongoConnection(MongoConnectionPool connectionPool)
             _state = MongoConnectionState.Initial;
         }
 
+        internal MongoConnection(MongoServerInstance serverInstance)
+        {
+            _serverInstance = serverInstance;
+            _createdAt = DateTime.UtcNow;
+            _state = MongoConnectionState.Initial;
+        }
+
         // public properties
         /// <summary>
         /// Gets the connection pool that this connection belongs to.
@@ -540,7 +547,10 @@ private void HandleException(Exception ex)
                     break;
                 case HandleExceptionAction.ClearConnectionPool:
                     Close();
-                    _connectionPool.Clear();
+                    if (_connectionPool != null)
+                    {
+                        _connectionPool.Clear();
+                    }
                     break;
                 default:
                     throw new MongoInternalException("Invalid HandleExceptionAction");