public TransportInitializationHandler(IHttpClient httpClient,
                                              IConnection connection,
                                              string connectionData,
                                              string transport,
                                              CancellationToken disconnectToken)
        {
            if (connection == null)
            {
                throw new ArgumentNullException("connection");
            }

            _connection = connection;
            _httpClient = httpClient;
            _connectionData = connectionData;
            _transport = transport;

            _initializationTask = new TaskCompletionSource<object>();
            _initializationInvoker = new ThreadSafeInvoker();

            // Default event
            OnFailure = () => { };

            // We want to fail if the disconnect token is tripped while we're waiting on initialization
            _tokenCleanup = disconnectToken.SafeRegister(_ =>
            {
                Fail();
            },
            state: null);

            TaskAsyncHelper.Delay(connection.TotalTransportConnectTimeout).Then(() =>
            {
                Fail(new TimeoutException(Resources.Error_TransportTimedOutTryingToConnect));
            });
        }
        private static void InitializeResolverDispose(this IDependencyResolver resolver, CancellationToken hostShutdownToken)
        {
            // TODO: Guard against multiple calls to this

            // When the host triggers the shutdown token, dispose the resolver
            hostShutdownToken.SafeRegister(state =>
            {
                ((IDependencyResolver)state).Dispose();
            },
            resolver);
        }
Example #3
0
        protected override void OnStart(IConnection connection, string connectionData, CancellationToken disconnectToken)
        {
            _disconnectRegistration = disconnectToken.SafeRegister(state =>
            {
                // _reconnectInvoker can be null if disconnectToken is tripped before the polling loop is started
                if (_reconnectInvoker != null)
                {
                    _reconnectInvoker.Invoke();
                }

                StopPolling();
            }, null);

            StartPolling(connection, connectionData);
        }
        public TransportInitializationHandler(TimeSpan failureTimeout, CancellationToken disconnectToken)
        {
            _initializationTask = new TaskCompletionSource<object>();
            _initializationInvoker = new ThreadSafeInvoker();

            // Default event
            OnFailure = () => { };

            // We want to fail if the disconnect token is tripped while we're waiting on initialization
            _tokenCleanup = disconnectToken.SafeRegister(_ =>
            {
                Fail();
            },
            state: null);

            TaskAsyncHelper.Delay(failureTimeout).Then(() =>
            {
                Fail(new TimeoutException(Resources.Error_TransportTimedOutTryingToConnect));
            });
        }
        public TransportInitializationHandler(IHttpClient httpClient,
                                              IConnection connection,
                                              string connectionData,
                                              string transport,
                                              CancellationToken disconnectToken, 
                                              TransportHelper transportHelper)
        {
            if (connection == null)
            {
                throw new ArgumentNullException("connection");
            }

            _connection = connection;
            _httpClient = httpClient;
            _connectionData = connectionData;
            _transport = transport;
            _transportHelper = transportHelper;

            _initializationTask = new TaskCompletionSource<object>();
            _initializationInvoker = new ThreadSafeInvoker();

            // Default event
            OnFailure = () => { };

            // We want to fail if the disconnect token is tripped while we're waiting on initialization
            _tokenCleanup = disconnectToken.SafeRegister(
                _ => Fail(new OperationCanceledException(Resources.Error_ConnectionCancelled, disconnectToken)),
                state: null);

            TaskAsyncHelper.Delay(connection.TotalTransportConnectTimeout)
                .Then(() =>
                {
                    // don't timeout once connect request has finished
                    if (Interlocked.CompareExchange(ref _state, InitializationState.Failed, InitializationState.Initial) ==
                        InitializationState.Initial)
                    {
                        Fail(new TimeoutException(Resources.Error_TransportTimedOutTryingToConnect));
                    }
                });
        }
        private void OpenConnection(IConnection connection,
                                    string data,
                                    CancellationToken disconnectToken,
                                    Action initializeCallback,
                                    Action<Exception> errorCallback)
        {
            // If we're reconnecting add /connect to the url
            bool reconnecting = initializeCallback == null;
            var callbackInvoker = new ThreadSafeInvoker();
            var requestDisposer = new Disposer();

            var url = (reconnecting ? connection.Url : connection.Url + "connect") + GetReceiveQueryString(connection, data);

            connection.Trace(TraceLevels.Events, "SSE: GET {0}", url);

            HttpClient.Get(url, req =>
            {
                _request = req;
                connection.PrepareRequest(_request);

                _request.Accept = "text/event-stream";
            }).ContinueWith(task =>
            {
                if (task.IsFaulted)
                {
                    Exception exception = task.Exception.Unwrap();
                    if (!ExceptionHelper.IsRequestAborted(exception))
                    {
                        if (errorCallback != null)
                        {
                            callbackInvoker.Invoke((cb, ex) => cb(ex), errorCallback, exception);
                        }
                        else if (reconnecting)
                        {
                            // Only raise the error event if we failed to reconnect
                            connection.OnError(exception);

                            Reconnect(connection, data, disconnectToken);
                        }
                    }
                    requestDisposer.Dispose();
                }
                else
                {
                    var response = task.Result;
                    Stream stream = response.GetStream();

                    var eventSource = new EventSourceStreamReader(connection, stream);

                    bool retry = true;

                    var esCancellationRegistration = disconnectToken.SafeRegister(state =>
                    {
                        retry = false;

                        ((IRequest)state).Abort();
                    },
                    _request);

                    eventSource.Opened = () =>
                    {
                        // If we're not reconnecting, then we're starting the transport for the first time. Trigger callback only on first start.
                        if (!reconnecting)
                        {
                            callbackInvoker.Invoke(initializeCallback);
                        }
                        else if (connection.ChangeState(ConnectionState.Reconnecting, ConnectionState.Connected))
                        {
                            // Raise the reconnect event if the connection comes back up
                            connection.OnReconnected();
                        }
                    };

                    eventSource.Message = sseEvent =>
                    {
                        if (sseEvent.EventType == EventType.Data)
                        {
                            if (sseEvent.Data.Equals("initialized", StringComparison.OrdinalIgnoreCase))
                            {
                                return;
                            }

                            bool timedOut;
                            bool disconnected;
                            TransportHelper.ProcessResponse(connection, sseEvent.Data, out timedOut, out disconnected);

                            if (disconnected)
                            {
                                retry = false;
                                connection.Disconnect();
                            }
                        }
                    };

                    eventSource.Closed = exception =>
                    {
                        if (exception != null)
                        {
                            // Check if the request is aborted
                            bool isRequestAborted = ExceptionHelper.IsRequestAborted(exception);

                            if (!isRequestAborted)
                            {
                                // Don't raise exceptions if the request was aborted (connection was stopped).
                                connection.OnError(exception);
                            }
                        }
                        requestDisposer.Dispose();
                        esCancellationRegistration.Dispose();
                        response.Dispose();

                        if (AbortResetEvent != null)
                        {
                            AbortResetEvent.Set();
                        }
                        else if (retry)
                        {
                            Reconnect(connection, data, disconnectToken);
                        }
                    };

                    eventSource.Start();
                }
            });

            var requestCancellationRegistration = disconnectToken.SafeRegister(state =>
            {
                if (state != null)
                {
                    // This will no-op if the request is already finished.
                    ((IRequest)state).Abort();
                }

                if (errorCallback != null)
                {
                    callbackInvoker.Invoke((cb, token) =>
                    {
            #if NET35 || WINDOWS_PHONE
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled));
            #else
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled, token));
            #endif
                    }, errorCallback, disconnectToken);
                }
            }, _request);

            requestDisposer.Set(requestCancellationRegistration);

            if (errorCallback != null)
            {
                TaskAsyncHelper.Delay(ConnectionTimeout).Then(() =>
                {
                    callbackInvoker.Invoke((conn, cb) =>
                    {
                        // Abort the request before cancelling
                        _request.Abort();

                        // Connection timeout occurred
                        cb(new TimeoutException());
                    },
                    connection,
                    errorCallback);
                });
            }
        }
        internal void OpenConnection(IConnection connection, string data, CancellationToken disconnectToken, bool reconnecting)
        {
            // If we're reconnecting add /connect to the url
            var url = reconnecting
                ? UrlBuilder.BuildReconnect(connection, Name, data)
                : UrlBuilder.BuildConnect(connection, Name, data);

            connection.Trace(TraceLevels.Events, "SSE: GET {0}", url);

            var getTask = HttpClient.Get(url, req =>
            {
                _request = req;
                _request.Accept = "text/event-stream";

                connection.PrepareRequest(_request);

            }, isLongRunning: true);

            var requestCancellationRegistration = disconnectToken.SafeRegister(state =>
            {
                _stop = true;

                // This will no-op if the request is already finished.
                ((IRequest)state).Abort();
            }, _request);
            
            getTask.ContinueWith(task =>
            {
                if (task.IsFaulted || task.IsCanceled)
                {
                    var exception = task.IsCanceled
                        ? new OperationCanceledException(Resources.Error_TaskCancelledException)
                        : task.Exception.Unwrap(); 

                    if (!reconnecting)
                    {
                        TransportFailed(exception);
                    }
                    else if (!_stop)
                    {
                        // Only raise the error event if we failed to reconnect
                        connection.OnError(exception);

                        Reconnect(connection, data, disconnectToken);
                    }

                    requestCancellationRegistration.Dispose();
                }
                else
                {
                    // If the disconnect token is canceled the response to the task doesn't matter.
                    if (disconnectToken.IsCancellationRequested)
                    {
                        return;
                    }

                    var response = task.Result;
                    Stream stream = response.GetStream();

                    var eventSource = new EventSourceStreamReader(connection, stream);

                    eventSource.Opened = () =>
                    {
                        // This will noop if we're not in the reconnecting state
                        if (connection.ChangeState(ConnectionState.Reconnecting, ConnectionState.Connected))
                        {
                            // Raise the reconnect event if the connection comes back up
                            connection.OnReconnected();
                        }
                    };

                    eventSource.Message = sseEvent =>
                    {
                        if (sseEvent.EventType == EventType.Data &&
                            !sseEvent.Data.Equals("initialized", StringComparison.OrdinalIgnoreCase))
                        {
                            ProcessResponse(connection, sseEvent.Data);
                        }
                    };

                    eventSource.Closed = exception =>
                    {
                        if (exception != null)
                        {
                            // Check if the request is aborted
                            if (!ExceptionHelper.IsRequestAborted(exception))
                            {
                                // Don't raise exceptions if the request was aborted (connection was stopped).
                                connection.OnError(exception);
                            }
                        }

                        requestCancellationRegistration.Dispose();
                        response.Dispose();

                        if (_stop)
                        {
                            AbortHandler.CompleteAbort();
                        }
                        else if (AbortHandler.TryCompleteAbort())
                        {
                            // Abort() was called, so don't reconnect
                        }
                        else
                        {
                            Reconnect(connection, data, disconnectToken);
                        }
                    };

                    eventSource.Start();
                }
            });
        }
        protected virtual Task InitializePersistentState()
        {
            _hostShutdownToken = _context.Environment.GetShutdownToken();

            _requestLifeTime = new HttpRequestLifeTime(this, WriteQueue, Trace, ConnectionId);

            // Create the TCS that completes when the task returned by PersistentConnection.OnConnected does.
            _connectTcs = new TaskCompletionSource<object>();

            // Create a token that represents the end of this connection's life
            _connectionEndTokenSource = new SafeCancellationTokenSource();
            _connectionEndToken = _connectionEndTokenSource.Token;

            // Handle the shutdown token's callback so we can end our token if it trips
            _hostRegistration = _hostShutdownToken.SafeRegister(state =>
            {
                ((SafeCancellationTokenSource)state).Cancel();
            },
            _connectionEndTokenSource);

            // When the connection ends release the request
            _connectionEndRegistration = CancellationToken.SafeRegister(state =>
            {
                ((HttpRequestLifeTime)state).Complete();
            },
            _requestLifeTime);

            return InitializeMessageId();
        }
Example #9
0
        private void PollingLoop(IConnection connection,
                                 string data,
                                 CancellationToken disconnectToken,
                                 Action initializeCallback,
                                 Action<Exception> errorCallback,
                                 bool raiseReconnect = false)
        {
            string url = connection.Url;

            IRequest request = null;
            var reconnectInvoker = new ThreadSafeInvoker();
            var callbackInvoker = new ThreadSafeInvoker();
            var requestDisposer = new Disposer();

            if (connection.MessageId == null)
            {
                url += "connect";
            }
            else if (raiseReconnect)
            {
                url += "reconnect";

                // FIX: Race if the connection is stopped and completely restarted between checking the token and calling
                //      connection.EnsureReconnecting()
                if (disconnectToken.IsCancellationRequested || !connection.EnsureReconnecting())
                {
                    return;
                }
            }

            url += GetReceiveQueryString(connection, data);

            #if NET35
            Debug.WriteLine(String.Format(CultureInfo.InvariantCulture, "LP: {0}", (object)url));
            #else
            Debug.WriteLine("LP: {0}", (object)url);
            #endif

            HttpClient.Post(url, req =>
            {
                request = req;
                connection.PrepareRequest(request);
            }).ContinueWith(task =>
            {
                bool shouldRaiseReconnect = false;
                bool disconnectedReceived = false;

                try
                {
                    if (!task.IsFaulted)
                    {
                        if (raiseReconnect)
                        {
                            // If the timeout for the reconnect hasn't fired as yet just fire the
                            // event here before any incoming messages are processed
                            reconnectInvoker.Invoke((conn) => FireReconnected(conn), connection);
                        }

                        if (initializeCallback != null)
                        {
                            // If the timeout for connect hasn't fired as yet then just fire
                            // the event before any incoming messages are processed
                            callbackInvoker.Invoke(initializeCallback);
                        }

                        // Get the response
                        var raw = task.Result.ReadAsString();

            #if NET35
                        Debug.WriteLine(String.Format(CultureInfo.InvariantCulture, "LP Receive: {0}", (object)raw));
            #else
                        Debug.WriteLine("LP Receive: {0}", (object)raw);
            #endif
                        TransportHelper.ProcessResponse(connection,
                                                        raw,
                                                        out shouldRaiseReconnect,
                                                        out disconnectedReceived);
                    }
                }
                finally
                {
                    if (disconnectedReceived)
                    {
                        connection.Disconnect();
                    }
                    else
                    {
                        bool requestAborted = false;

                        if (task.IsFaulted)
                        {
                            reconnectInvoker.Invoke();

                            // Raise the reconnect event if we successfully reconnect after failing
                            shouldRaiseReconnect = true;

                            // Get the underlying exception
                            Exception exception = task.Exception.Unwrap();

                            // If the error callback isn't null then raise it and don't continue polling
                            if (errorCallback != null)
                            {
                                callbackInvoker.Invoke((cb, ex) => cb(ex), errorCallback, exception);
                            }
                            else
                            {
                                // Figure out if the request was aborted
                                requestAborted = ExceptionHelper.IsRequestAborted(exception);

                                // Sometimes a connection might have been closed by the server before we get to write anything
                                // so just try again and don't raise OnError.
                                if (!requestAborted && !(exception is IOException))
                                {
                                    // Raise on error
                                    connection.OnError(exception);

                                    // If the connection is still active after raising the error event wait for 2 seconds
                                    // before polling again so we aren't hammering the server
                                    TaskAsyncHelper.Delay(ErrorDelay).Then(() =>
                                    {
                                        if (!disconnectToken.IsCancellationRequested)
                                        {
                                            PollingLoop(connection,
                                                data,
                                                disconnectToken,
                                                initializeCallback: null,
                                                errorCallback: null,
                                                raiseReconnect: shouldRaiseReconnect);
                                        }
                                    });
                                }
                            }
                        }
                        else
                        {
                            if (!disconnectToken.IsCancellationRequested)
                            {
                                // Continue polling if there was no error
                                PollingLoop(connection,
                                            data,
                                            disconnectToken,
                                            initializeCallback: null,
                                            errorCallback: null,
                                            raiseReconnect: shouldRaiseReconnect);
                            }
                        }
                    }
                    requestDisposer.Dispose();
                }
            });

            var requestCancellationRegistration = disconnectToken.SafeRegister(req =>
            {
                if (req != null)
                {
                    // This will no-op if the request is already finished.
                    req.Abort();
                }

                // Prevent the connection state from switching to the reconnected state.
                reconnectInvoker.Invoke();

                if (errorCallback != null)
                {
                    callbackInvoker.Invoke((cb, token) =>
                    {
            #if NET35 || WINDOWS_PHONE
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled));
            #else
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled, token));
            #endif
                    }, errorCallback, disconnectToken);
                }
            }, request);

            requestDisposer.Set(requestCancellationRegistration);

            if (initializeCallback != null)
            {
                TaskAsyncHelper.Delay(ConnectDelay).Then(() =>
                {
                    callbackInvoker.Invoke(initializeCallback);
                });
            }

            if (raiseReconnect)
            {
                TaskAsyncHelper.Delay(ReconnectDelay).Then(() =>
                {
                    // Fire the reconnect event after the delay. This gives the
                    reconnectInvoker.Invoke((conn) => FireReconnected(conn), connection);
                });
            }
        }
        private void OpenConnection(IConnection connection,
                                    string data,
                                    CancellationToken disconnectToken,
                                    Action initializeCallback,
                                    Action<Exception> errorCallback)
        {
            // If we're reconnecting add /connect to the url
            bool reconnecting = initializeCallback == null;
            var callbackInvoker = new ThreadSafeInvoker();
            var requestDisposer = new Disposer();

            var url = (reconnecting ? connection.Url : connection.Url + "connect") + GetReceiveQueryString(connection, data);
            IRequest request = null;

            #if NET35
            Debug.WriteLine(String.Format(CultureInfo.InvariantCulture, "SSE: GET {0}", (object)url));
            #else
            Debug.WriteLine("SSE: GET {0}", (object)url);
            #endif

            HttpClient.Get(url, req =>
            {
                request = req;
                connection.PrepareRequest(request);

                request.Accept = "text/event-stream";
            }).ContinueWith(task =>
            {
                if (task.IsFaulted)
                {
                    Exception exception = task.Exception.Unwrap();
                    if (!ExceptionHelper.IsRequestAborted(exception))
                    {
                        if (errorCallback != null)
                        {
                            callbackInvoker.Invoke((cb, ex) => cb(ex), errorCallback, exception);
                        }
                        else if (reconnecting)
                        {
                            // Only raise the error event if we failed to reconnect
                            connection.OnError(exception);

                            Reconnect(connection, data, disconnectToken);
                        }
                    }
                    requestDisposer.Dispose();
                }
                else
                {
                    IResponse response = task.Result;
                    Stream stream = response.GetResponseStream();

                    var eventSource = new EventSourceStreamReader(stream);
                    bool retry = true;

                    var esCancellationRegistration = disconnectToken.SafeRegister(es =>
                    {
                        retry = false;
                        es.Close();
                    }, eventSource);

                    eventSource.Opened = () =>
                    {
                        if (!reconnecting)
                        {
                            callbackInvoker.Invoke(initializeCallback);
                        }
                        else if (connection.ChangeState(ConnectionState.Reconnecting, ConnectionState.Connected))
                        {
                            // Raise the reconnect event if the connection comes back up
                            connection.OnReconnected();
                        }
                    };

                    eventSource.Message = sseEvent =>
                    {
                        if (sseEvent.EventType == EventType.Data)
                        {
                            if (sseEvent.Data.Equals("initialized", StringComparison.OrdinalIgnoreCase))
                            {
                                return;
                            }

                            bool timedOut;
                            bool disconnected;
                            TransportHelper.ProcessResponse(connection, sseEvent.Data, out timedOut, out disconnected);

                            if (disconnected)
                            {
                                retry = false;
                                connection.Disconnect();
                            }
                        }
                    };

                    eventSource.Closed = exception =>
                    {
                        bool isRequestAborted = false;

                        if (exception != null)
                        {
                            // Check if the request is aborted
                            isRequestAborted = ExceptionHelper.IsRequestAborted(exception);

                            if (!isRequestAborted)
                            {
                                // Don't raise exceptions if the request was aborted (connection was stopped).
                                connection.OnError(exception);
                            }
                        }

                        // Skip reconnect attempt for aborted requests
                        if (!isRequestAborted && retry)
                        {
                            Reconnect(connection, data, disconnectToken);
                        }
                    };

                    // See http://msdn.microsoft.com/en-us/library/system.net.httpwebresponse.close.aspx
                    eventSource.Disabled = () =>
                    {
                        requestDisposer.Dispose();
                        esCancellationRegistration.Dispose();
                        response.Close();
                    };

                    eventSource.Start();
                }
            });

            var requestCancellationRegistration = disconnectToken.SafeRegister(req =>
            {
                if (req != null)
                {
                    // This will no-op if the request is already finished.
                    req.Abort();
                }

                if (errorCallback != null)
                {
                    callbackInvoker.Invoke((cb, token) =>
                    {
            #if NET35 || WINDOWS_PHONE
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled));
            #else
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled, token));
            #endif
                    }, errorCallback, disconnectToken);
                }
            }, request);

            requestDisposer.Set(requestCancellationRegistration);

            if (errorCallback != null)
            {
                TaskAsyncHelper.Delay(ConnectionTimeout).Then(() =>
                {
                    callbackInvoker.Invoke((conn, cb) =>
                    {
                        // Abort the request before cancelling
                        request.Abort();

                        // Connection timeout occurred
                        cb(new TimeoutException());
                    },
                    connection,
                    errorCallback);
                });
            }
        }
        protected virtual void InitializePersistentState()
        {
            _hostShutdownToken = _context.HostShutdownToken();

            Completed = new TaskCompletionSource<object>();

            // Create a token that represents the end of this connection's life
            _connectionEndTokenSource = new SafeCancellationTokenSource();
            _connectionEndToken = _connectionEndTokenSource.Token;

            // Handle the shutdown token's callback so we can end our token if it trips
            _hostRegistration = _hostShutdownToken.SafeRegister(state =>
            {
                state.Cancel();
            },
            _connectionEndTokenSource);
        }
        private void OpenConnection(IConnection connection,
                                    string data,
                                    CancellationToken disconnectToken,
                                    Action initializeCallback,
                                    Action<Exception> errorCallback)
        {
            // If we're reconnecting add /connect to the url
            bool reconnecting = initializeCallback == null;
            var callbackInvoker = new ThreadSafeInvoker();
            var requestDisposer = new Disposer();
            Action initializeInvoke = () =>
            {
                callbackInvoker.Invoke(initializeCallback);
            };
            var url = connection.Url + (reconnecting ? "reconnect" : "connect") + GetReceiveQueryString(connection, data);

            connection.Trace(TraceLevels.Events, "SSE: GET {0}", url);

            HttpClient.Get(url, req =>
            {
                _request = req;
                _request.Accept = "text/event-stream";

                connection.PrepareRequest(_request);

            }, isLongRunning: true).ContinueWith(task =>
            {
                if (task.IsFaulted || task.IsCanceled)
                {
                    Exception exception;

                    if (task.IsCanceled)
                    {
                        exception = new OperationCanceledException(Resources.Error_TaskCancelledException);
                    }
                    else
                    {
                        exception = task.Exception.Unwrap();
                    }

                    if (errorCallback != null)
                    {
                        callbackInvoker.Invoke((cb, ex) => cb(ex), errorCallback, exception);
                    }
                    else if (!_stop && reconnecting)
                    {
                        // Only raise the error event if we failed to reconnect
                        connection.OnError(exception);

                        Reconnect(connection, data, disconnectToken);
                    }
                    requestDisposer.Dispose();
                }
                else
                {
                    // If the disconnect token is canceled the response to the task doesn't matter.
                    if (disconnectToken.IsCancellationRequested)
                    {
                        return;
                    }

                    var response = task.Result;
                    Stream stream = response.GetStream();

                    var eventSource = new EventSourceStreamReader(connection, stream);

                    var esCancellationRegistration = disconnectToken.SafeRegister(state =>
                    {
                        _stop = true;

                        ((IRequest)state).Abort();
                    },
                    _request);

                    eventSource.Opened = () =>
                    {
                        // This will noop if we're not in the reconnecting state
                        if (connection.ChangeState(ConnectionState.Reconnecting, ConnectionState.Connected))
                        {
                            // Raise the reconnect event if the connection comes back up
                            connection.OnReconnected();
                        }
                    };

                    eventSource.Message = sseEvent =>
                    {
                        if (sseEvent.EventType == EventType.Data)
                        {
                            if (sseEvent.Data.Equals("initialized", StringComparison.OrdinalIgnoreCase))
                            {
                                return;
                            }

                            bool shouldReconnect;
                            bool disconnected;
                            TransportHelper.ProcessResponse(connection, sseEvent.Data, out shouldReconnect, out disconnected, initializeInvoke);

                            if (disconnected)
                            {
                                _stop = true;
                                connection.Disconnect();
                            }
                        }
                    };

                    eventSource.Closed = exception =>
                    {
                        if (exception != null)
                        {
                            // Check if the request is aborted
                            bool isRequestAborted = ExceptionHelper.IsRequestAborted(exception);

                            if (!isRequestAborted)
                            {
                                // Don't raise exceptions if the request was aborted (connection was stopped).
                                connection.OnError(exception);
                            }
                        }

                        requestDisposer.Dispose();
                        esCancellationRegistration.Dispose();
                        response.Dispose();

                        if (_stop)
                        {
                            AbortHandler.CompleteAbort();
                        }
                        else if (AbortHandler.TryCompleteAbort())
                        {
                            // Abort() was called, so don't reconnect
                        }
                        else
                        {
                            Reconnect(connection, data, disconnectToken);
                        }
                    };

                    eventSource.Start();
                }
            });

            var requestCancellationRegistration = disconnectToken.SafeRegister(state =>
            {
                if (state != null)
                {
                    // This will no-op if the request is already finished.
                    ((IRequest)state).Abort();
                }

                if (errorCallback != null)
                {
                    callbackInvoker.Invoke((cb, token) =>
                    {
#if !NET35
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled, token));
#else
                        cb(new OperationCanceledException(Resources.Error_ConnectionCancelled));
#endif
                    }, errorCallback, disconnectToken);
                }
            }, _request);

            requestDisposer.Set(requestCancellationRegistration);
        }
        private void PollingSetup(IConnection connection,
                                  string data,
                                  CancellationToken disconnectToken,
                                  PollingRequestHandler requestHandler,
                                  Action onInitialized)
        {
            // reconnectInvoker is created new on each poll
            var reconnectInvoker = new ThreadSafeInvoker();

            var disconnectRegistration = disconnectToken.SafeRegister(state =>
            {
                reconnectInvoker.Invoke();
                requestHandler.Stop();
            }, null);

            requestHandler.ResolveUrl = () =>
            {
                var url = connection.Url;

                if (connection.MessageId == null)
                {
                    url += "connect";
                    connection.Trace(TraceLevels.Events, "LP Connect: {0}", url);
                }
                else if (IsReconnecting(connection))
                {
                    url += "reconnect";
                    connection.Trace(TraceLevels.Events, "LP Reconnect: {0}", url);
                }
                else
                {
                    url += "poll";
                    connection.Trace(TraceLevels.Events, "LP Poll: {0}", url);
                }

                url += GetReceiveQueryString(connection, data);

                return url;
            };

            requestHandler.PrepareRequest += req =>
            {
                connection.PrepareRequest(req);
            };

            requestHandler.OnMessage += message =>
            {
                var shouldReconnect = false;
                var disconnectedReceived = false;

                connection.Trace(TraceLevels.Messages, "LP: OnMessage({0})", message);

                TransportHelper.ProcessResponse(connection,
                                                message,
                                                out shouldReconnect,
                                                out disconnectedReceived,
                                                onInitialized);

                if (IsReconnecting(connection))
                {
                    // If the timeout for the reconnect hasn't fired as yet just fire the 
                    // event here before any incoming messages are processed
                    TryReconnect(connection, reconnectInvoker);
                }

                if (shouldReconnect)
                {
                    // Transition into reconnecting state
                    connection.EnsureReconnecting();
                }

                if (disconnectedReceived)
                {
                    connection.Disconnect();
                }
            };

            requestHandler.OnError += exception =>
            {
                reconnectInvoker.Invoke();

                // Transition into reconnecting state
                connection.EnsureReconnecting();

                // Sometimes a connection might have been closed by the server before we get to write anything
                // so just try again and raise OnError.
                if (!ExceptionHelper.IsRequestAborted(exception) && !(exception is IOException))
                {
                    connection.OnError(exception);
                }
                else
                {
                    requestHandler.Stop();
                }
            };

            requestHandler.OnPolling += () =>
            {
                // Capture the cleanup within a closure so it can persist through multiple requests
                TryDelayedReconnect(connection, reconnectInvoker);
            };

            requestHandler.OnAfterPoll = exception =>
            {
                if (AbortHandler.TryCompleteAbort())
                {
                    // Abort() was called, so don't reconnect
                    requestHandler.Stop();
                }
                else
                {
                    reconnectInvoker = new ThreadSafeInvoker();

                    if (exception != null)
                    {
                        // Delay polling by the error delay
                        return TaskAsyncHelper.Delay(ErrorDelay);
                    }
                }

                return TaskAsyncHelper.Empty;
            };

            requestHandler.OnAbort += _ =>
            {
                disconnectRegistration.Dispose();

                // Complete any ongoing calls to Abort()
                // If someone calls Abort() later, have it no-op
                AbortHandler.CompleteAbort();
            };
        }
        protected virtual void InitializePersistentState()
        {
            _hostShutdownToken = _context.HostShutdownToken();

            _requestLifeTime = new HttpRequestLifeTime(WriteQueue, Trace, ConnectionId);

            // Create a token that represents the end of this connection's life
            _connectionEndTokenSource = new SafeCancellationTokenSource();
            _connectionEndToken = _connectionEndTokenSource.Token;

            // Handle the shutdown token's callback so we can end our token if it trips
            _hostRegistration = _hostShutdownToken.SafeRegister(state =>
            {
                ((SafeCancellationTokenSource)state).Cancel();
            },
            _connectionEndTokenSource);

            // When the connection ends release the request
            _connectionEndRegistration = CancellationToken.SafeRegister(state =>
            {
                ((HttpRequestLifeTime)state).Complete();
            },
            _requestLifeTime);
        }